# Single Point Threading Issue - might be gearing?



## WobblyHand (Mar 14, 2020)

Thought I'd try some threading.  I have a small rod I'd like to thread in 8-32.  So, having never done this before, looked up the appropriate gear ratio and other things to do an 8-32 on my LMS 7350 high torque mini-lathe.  The gear chart on gear chart says to use the following set up:

ABCD20Any gearAny gear40
I used 20/80/60/40.  (Default setup is 20/80/20/80)  60 seemed to be the only gear that would mate up with the 40.  "Any gear" is kind of confusing to me.   Does "any gear" mean pick whatever might properly engage the gears?  


Used a piece of 1/2" aluminum for practice.  It cut like 6061, but since it was unlabeled, not sure of the alloy.  Used sulfur cutting oil since that is what I had.  End result was not 32 TPI.  The threads seem well formed, but seem to be around 21-22 threads/0.490" or 45 TPI!  (OK, they aren't pretty under 60x, but due to the slow speed that I cut them at, they aren't bad.)  I'm surprised about the wrong TPI.  I engaged the lead screw at the same mark every time.


So what am I missing?  

The mini-lathe has a 16 TPI lead screw.  (And I did physically count 16 threads in an inch.)  Maybe a red herring, but I never could engage the lead screw on the mark (1) of the thread dial.  I could engage just before, or just after, but never on the mark.  I practiced this a lot, and it seems the dial is misaligned?


I'd appreciate any help that you could give.


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## MrWhoopee (Mar 14, 2020)

Confusing to say the least. If B and C are the two gears on a common stud, changing the ratio of those two will definitely change the TPI.

Edit: Reading the change gear page, I find this

"In the change gear results, many of the combinations have "Any gear" in columns B and C. This means that you can use a gear with any number of teeth in position B. It is an idler and does not affect the overall gear ratio. Use a gear that makes it easy to properly engage the gears. For these combinations, you can use any gear for position C; this gear acts only as a spacer and does not engage the other gears. "

Your D gear should engage the B gear, C is not actually used in the drive train.


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## WobblyHand (Mar 14, 2020)

A is the 20T metal gear.  B is the 80T plastic gear that mates with A.  C is coaxial with B and on the top of B.  C is 60T.  D is 40T and attached to the lead screw.  Still don't know what "Any gear" means.  But it's clear that 20/80/60/40 isn't correct.


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## MrWhoopee (Mar 14, 2020)

WobblyHand said:


> A is the 20T metal gear.  B is the 80T plastic gear that mates with A.  C is coaxial with B and on the top of B.  C is 60T.  D is 40T and attached to the lead screw.  Still don't know what "Any gear" means.  But it's clear that 20/80/60/40 isn't correct.


Read my previous post. C gear is not used at all, it is just a spacer. Both A and D engage B.


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## middle.road (Mar 14, 2020)

A cup of coffee, staring at the change gear chart with pencil and scratch paper, and I'm confused as well.

I opened the manual but cannot figure out the tooth count on the spindle gear (#4 - p/n1320).
Thought I might work out the math on the gears.

Pull off the thread indicator and count the teeth on it's gear. It should be lining up . . .
Count out the teeth on 'A' just to be certain. And double check 'D' as well.


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## WobblyHand (Mar 14, 2020)

Further searching this site, I found the answer.  Post #5 of gear change for 18 TPI has a video, which clears up the issue.  Yeah, it's obvious once you've seen it!  The write up on LMS is incomplete for a newbie, in my opinion.  Sure left me puzzled.  Seeing the video clears up my confusion.  I'll try it again on aluminum to see that I got it right.  Then I'll try it on some O1 at the correct diameter for a #8 screw.


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## WobblyHand (Mar 14, 2020)

middle.road said:


> A cup of coffee, staring at the change gear chart with pencil and scratch paper, and I'm confused as well.
> 
> I opened the manual but cannot figure out the tooth count on the spindle gear (#4 - p/n1320).
> Thought I might work out the math on the gears.
> ...


From viewing the video, I was just doing the setup wrong.  It's a miracle that it was even close.  (If one calls 40% error close!)  I'll try it the way it was suggested in the video and report back.

I will check the thread indicator and count teeth.  How many teeth should the indicator have?  16?


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## benmychree (Mar 14, 2020)

The problem is that you are creating a compounded gear train, the gear on the QC box should mesh with the large gear in the middle, not the gear that is on the same shaft with it. Likely, the gear on the thread dial can be re positioned to make the marks line up properly.


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## T Bredehoft (Mar 14, 2020)

On the dial, with the machine NOT running, engage the half nuts, loosen the screw and rotate the dial till the marks line up, tighten the screw.


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## WobblyHand (Mar 14, 2020)

T Bredehoft said:


> On the dial, with the machine NOT running, engage the half nuts, loosen the screw and rotate the dial till the marks line up, tighten the screw.


Which screw, the one that holds the threading dial housing to the apron?  I did that, and it seems to help some.


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## T Bredehoft (Mar 14, 2020)

On my lathe the  dial is held on with a screw in the middle. You might need to space the housing a   bit farther from th saddle.


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## WobblyHand (Mar 14, 2020)

Ok.  Now have 32 TPI.  But kind of sad looking threads.  There's a lot of swarf and bent over thread edges.  I seem to be having trouble always hitting the mark, sometimes it drops in, and sometimes it hangs and drops in the next "detent".  Would this lack of consistency of hitting the mark make the threads ratty?  Is there some better way to practice?  (It's clear I need to work on this.)  What material is cheap and gives one a similar enough experience as single threading metal?  From reading on HMF I think someone mentioned PVC pipe.  That would help for the coarse threads.


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## WobblyHand (Mar 14, 2020)

T Bredehoft said:


> On my lathe the  dial is held on with a screw in the middle. You might need to space the housing a   bit farther from th saddle.


Mine pivots on the screw into the side of the apron.  The screw is parallel to the ways.  I can adjust the depth of the engagement of the dial gear to the lead screw by rotating the dial face toward me, or more vertical.  As far as I can tell that's the only adjustment I have.  That's what I played with.


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## WobblyHand (Mar 14, 2020)

Hmm, forgot the picture of the awful threads. 


How do you make nicer threads?


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## royesses (Mar 14, 2020)

Just ran this on the calculator (https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe) Many combinations will work :


*Gear A**Gear B**Gear C**Gear D**Actual TPI*20ANY403230ANY603240ANY80322020408032203060803220408080322080603032208080403221355060322160503532304040603230456080323060404032306080803230806045323080806032402020803240403060324060304032503521603260302080326045308032804020803280603080328080306032




​Roy


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## WobblyHand (Mar 14, 2020)

When I started, this morning, I had no idea that one could do ABD, and you needed to move the spacer as well as the pivots.  Now, I know.     There sure are a lot of combinations to get 32 TPI!

Sad to say, if I had actually looked at the sticker on the side of the gearbox cover, I would have seen a simplified table, and both the ABCD and ABD diagrams.   I had turned over the cover, and never noticed it.


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## T Bredehoft (Mar 14, 2020)

WobblyHand said:


> How do you make nicer threads?



Cut 10L12, Ledloy its a free machining steel. They will be a lot nicer.


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## ttabbal (Mar 14, 2020)

You can learn on PVC for higher pitch threads. Don't know that I ever did more than 24, but it worked well. Aluminum and 12L14 work well as well.


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## mikey (Mar 14, 2020)

T Bredehoft said:


> Cut 10L12, Ledloy its a free machining steel. They will be a lot nicer.



Tom, I never heard of 10l12. Ledloy is usually 12L14. Was that a typo?


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## WobblyHand (Mar 14, 2020)

I have some 1215 (no lead) but it's hex.  I can turn it down and try some.  It's supposed to be free machining, but not quite as good as 12L14.  I'm shying away from 12L14, etc. just due to the lead.  Not sure how to legitimately dispose of the chips.  Probably will also buy a stick of 1/2" pvc pipe, that should be cheap enough.  ($2 for 10 feet, quantity 1)


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## AGCB97 (Mar 14, 2020)

I had a similar problem with the threading dial and the 1/2 nuts not wanting to go in at the line. Solved it by putting a magic marker line slightly right of engraved line and now it always goes in when I want it. You may be getting 'just before' one time and 'just after' the next which would not make for nice threads.
Aaron


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## WobblyHand (Mar 14, 2020)

AGCB97 said:


> I had a similar problem with the threading dial and the 1/2 nuts not wanting to go in at the line. Solved it by putting a magic marker line slightly right of engraved line and now it always goes in when I want it. You may be getting 'just before' one time and 'just after' the next which would not make for nice threads.
> Aaron


Thanks Aaron.  I'm pretty sure that is what happened for this second set of threads (32TPI, _not the wrongly geared_ 45TPI).  What happens if you alternate just before, or just after?  What does it look like?  (Ragged edges?)

The first set of threads, although the wrong TPI, were much cleaner.  I couldn't hit the mark, but what I did was consistent.  The second set with the correct TPI had multiple instances of jitter around the mark.


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## T Bredehoft (Mar 14, 2020)

mikey said:


> Tom, I never heard of 10l12. Ledloy is usually 12L14. Was that a typo?



No it wasn't a typo, it was a mistake.  I thought I remembered  two grades of ledloy, musta been a nightmare.  OK, ohter grades, 11L17 and 41L40. I'd like to try that, i use a lot of  4140.,


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## mikey (Mar 14, 2020)

Okay, thanks, Tom. I can't even begin to count the number mistakes I've made here ...


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## darkzero (Mar 14, 2020)

WobblyHand said:


> Hmm, forgot the picture of the awful threads.
> View attachment 316670
> 
> How do you make nicer threads?



Are you feeding with the compound (modified flank method)? If yes make sure your compound is set correctly. Many small import lathes don't have a full scale on their compound, my 12x included. With your compound set parallel to the spindle axis, if your scale reads 0 & you set the compound to 29.5° on the scale that's incorrect for threading. This usually causes jagged rolled over funny looking thread forms. It would need to be set at 60.5° which the scale on most of these lathes don't read that far. You'll need a protractor or something else to set the correct angle.

If this was the case & you don't have a protractor forget the compound & try feeding in with the cross slide. 32 TPI is a fine enough thread where you'll be ok feeding with just the cross slide.


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## T Bredehoft (Mar 14, 2020)

Just a small comment here. 60.5 or  29.5 is not absolute. The angle must be a tiny bit off of 30 or 60 so that there is cutting on both sides of the threading tool.  A cut at exactly 30 or 60 will not clean up one side of the cut, that's why we offset the tool .


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## homebrewed (Mar 14, 2020)

FYI, you don't necessarily need to disengage the half nuts on lathes that can be run in reverse.  At the end of a pass, stop the motor, back the cutter out and run the motor/lead screw in reverse until the cutter goes past the work.  Stop the motor, move the cutter in for the next pass, switch to the "normal" direction and do your next pass.

Kind of painful to do it this way but it will separate the threading dial issue from other things that might be going on.  And this method is the only way to cut metric threads with a 16TPI lead screw.


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## T Bredehoft (Mar 14, 2020)

Using a stop on the cross-feed, so you can run the carriage  back in and just increment the compound, with the lathe going at a moderately slow speed you can (anyway I can) make a pass every  couple of seconds. )  (short thread) I did it at work fourty years ago and still  do.

It helps if the thread you are chasing can be chased using any of the gears (notches) on the leadscrew


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## WobblyHand (Mar 14, 2020)

darkzero said:


> Are you feeding with the compound (modified flank method)? If yes make sure your compound is set correctly. Many small import lathes don't have a full scale on their compound, my 12x included. With your compound set parallel to the spindle axis, if your scale reads 0 & you set the compound to 29.5° on the scale that's incorrect for threading. This usually causes jagged rolled over funny looking thread forms. It would need to be set at 60.5° which the scale on most of these lathes don't read that far. You'll need a protractor or something else to set the correct angle.
> 
> If this was the case & you don't have a protractor forget the compound & try feeding in with the cross slide. 32 TPI is a fine enough thread where you'll be ok feeding with just the cross slide.
> 
> View attachment 316677


My setup is the modified flank (your first picture).  I set the angle to 29.5 degrees using a protractor.  Or rather, to 29.5 indicated on the protractor.  I think the problem with the threads was dithering about the mark on the thread dial.  I tried again using a practice piece of PVC pipe and the threads came out cleaner.  Of course, stopping on time is still a problem for me.  But the thread is looking quite a bit better.  I was able to hit the threading dial mark consistently.  (Actually, just before the mark, but it was consistent.)


Next, I'll try doing this thread on some 1215 steel.  I had some hex stock that I machined to round.  If the threads are good and clean, then I will try Joe Pi's method of threading with an upside down bit going from headstock to tailstock.  What I am really trying to do is to make a replacement for this damaged part:


On this piece, the threads got destroyed on the right hand side.  (This was a purchased part.)  My reflexes aren't fast enough to stop the threading if I go from tailstock to headstock.  Maybe Joe Pi's threading method will let me make this.  The material is O1, the thread is 8-32.  Center diameter is 0.1875".


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## mikey (Mar 14, 2020)

This is the kind of part that a Sherline lathe excels at making because threads are cut manually by turning the leadscrew by hand. You might try spinning the chuck by hand to see if it works. If it does then it might be a good idea to make a handwheel to turn the spindle on these smaller threads.


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## WobblyHand (Mar 14, 2020)

mikey said:


> This is the kind of part that a Sherline lathe excels at making because threads are cut manually by turning the leadscrew by hand. You might try spinning the chuck by hand to see if it works. If it does then it might be a good idea to make a handwheel to turn the spindle on these smaller threads.


If I turn the chuck manually, the leadscrew advances.  How would one attach the handwheel?  Removing one of the spindle nuts? (#5) There seem to be two of them, I guess acting as a jam nut.  M27x1.5 is what the parts list shows.  They are more of a spanner nut, rather than a hex nut.  There's no spare thread left on the spindle.


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## darkzero (Mar 15, 2020)

WobblyHand said:


> My reflexes aren't fast enough to stop the threading if I go from tailstock to headstock.



How close do you need to get to the shoulder? Does the part require no thread relief between the thread & shoulder? With practice you should be able to get it. I can thread into a 1/16" wide thread relief no problem disengaging the half nut without any aid.

By aid what I mean is a dial indicator. When I single point threads I set up a dial indicator to read zero 10 thou off a shoulder or blind hole. I use the modified flank method for threading so to set the dial indicator after setting tool position off the work, I retract the cross slide, advance the compound to the full depth required for the thread pitch being cut, then move the carriage so the cutter bottoms out on the shoulder or the blind hole. Then I set the dial indicator for the carriage +.010. I set the 0 mark at 12:00, the needle starts moving from 6:00 on my DI.

I'm certainly not a pro or even close but I'm able to disengage at 0 on the dial indicator pretty consistently or within a few thou. So in theory I could probably get even close than 10 thou but I never have a need to get that close & to play it safe. Sometimes I thread with no thread relief at all using this method. I know I'm not the only one that uses a dial indicator for threading. Although I have a DRO now, a digital display is pretty much useless for the Z axis for threading.

Threading from headstock to the tailstock is great & allows you to run higher spindle speeds than you normally would & should give you a better surface finish but there are downsides too. Pretty much always need a thread relief which most people use anyway (stronger with no thread relief). But if threading a very coarse pitch the thread dial will be moving pretty fast. There is no room for error engaging the half nut on a specific mark when needed. At least with threading conventionally from right to left you do have room for error & can reset with no damage if you miss your mark. But this shouldn't be an issue once you are used to it. If you are threading a metric thread & you have an imperial lathe (or vice versa) you can't use the half nut here & if the thread is up to a shoulder or a blind hole, getting your carriage lined up for the next thread will be tricky. On top of all that you'll need LH tools. Not knocking the method, just saying it's not for everyone.




No thread relief


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## darkzero (Mar 15, 2020)

WobblyHand said:


> If I turn the chuck manually, the leadscrew advances.  How would one attach the handwheel?  Removing one of the spindle nuts? (#5) There seem to be two of them, I guess acting as a jam nut.  M27x1.5 is what the parts list shows.  They are more of a spanner nut, rather than a hex nut.  There's no spare thread left on the spindle.
> View attachment 316717



Don't remove those spindle nuts, they are usually for bearing preload. Some people attach a handwheel to the leadscrew, on the right end. I have also seen people make a hand wheel to attach to the ID or OD of the spindle.


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## homebrewed (Mar 15, 2020)

For these small lathes, many have made an expanding mandrel to manually turn the spindle.  The most-often used approach is a rod and tube with a diagonal cut so they slide past each other and capture the inside of the spindle when tightened against each other using a bolt .  The other end of this thing has a crank on the end of the rod you use to turn the spindle, which also drives the lead screw.  With this approach you get all the control you need, even with coarse threads (which can be pretty "exciting" to cut under power).

The controller on my mini lathe can turn the motor at very low speed so I haven't found the need to make one of these yet.  I've cut 1/2-20 threads under power but the RPMs were low, and I had the luxury of being able to cut a run-out groove to make things easier.  Threading from headstock to tailstock sounds pretty good, too, but you still can't get right up to a shoulder unless you exclusively advance the cross slide -- setting the compound (or top slide) to 29.5 degrees and advancing will move the cutter toward the shoulder.  Maybe I'm wrong here but it seems like an Aw Shucks scenario to me....waiting for someone to set me right .


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## mikey (Mar 15, 2020)

WobblyHand said:


> If I turn the chuck manually, the leadscrew advances.  How would one attach the handwheel?  Removing one of the spindle nuts? (#5) There seem to be two of them, I guess acting as a jam nut.  M27x1.5 is what the parts list shows.  They are more of a spanner nut, rather than a hex nut.  There's no spare thread left on the spindle.



There are a few threads about this mod. This one is pretty good, and this is also illustrative. Essentially, you are looking to somehow tie a hand wheel to the spindle so you can manually turn the wheel to provide the motive force to the leadscrew via the gearing that is set up for the threads you wish to cut. It will allow you to cut threads without worrying about crashing the tool into a shoulder. 

You can also do the Joe Pi thing but as Will said, there are advantages and disadvantages to all these methods.


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## T Bredehoft (Mar 15, 2020)

mikey said:


> a good idea to make a handwheel to turn the spindle on these smaller threads.



Yes, that is an excellent Idea. I've been doing it for several years. What I did ws copoy the mechinism that hods a bicycle handbar in place. Make a piece of round steel, just under the ID of the  lathe spindle on the left end of the lathe. abut 2 /12/3 inches long. Drill half way through with (for example) clearance for a 3/8" bolt, drill the rest of the way through with a tap drill for 38-16 p itch threads. 
Tap the small end. Then  (this is the hardest part) saw the longest diagonal you can manage, the more the better and Mill/file/polishboth cut surfaces smooth. Make/use a handle/crank drilled to clear a 3/8 bolt, assemble the   whole, insert into the  back of the spindle, and tighten the screw,  drawing the two inside pieces together.  NOw you can crank your chuck awile lthereading. you'll have to determine how much you can take with each pass. but you can stop rotation at the same place eaach time you get to the end of the cut, or go the other way   (Joe Pie)  and it will all work out. There's a video somewhere on the internet showing a  guy threading a brass shaft with a pedal operated lathe.


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## RJSakowski (Mar 15, 2020)

My Atlas/Craftsman 6 x 18 also has a non-adjustable thread dial, it is possible to adjust the dial by adding/removing shims between the thread dial mechanism and the the carriage apron.  The shim will change the relative position of the thread dial mechanism to the half nuts.  The range of shims will be less than the lead screw pitch so if the lead screw is 16 tpi, the maximum range would be .063".  Rather than try to make shims  of impossible thickness (thinness?) add .063" to the desired thickness which will move the thread dial out an extra tooth.  A range of shims can be made using soft drink cans and some varying thickness washers turned on the lathe.


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## MrWhoopee (Mar 15, 2020)

I would never try to discourage someone from trying new things or improving their skills.

However, if the object is to produce that little pin from O-1, I suggest simply using a die and (if necessary) making a very narrow undercut at the shoulder. It is difficult enough to get a decent surface finish threading O-1 at the appropriate cutting speeds. For this diameter, I calculate a turning speed of 1000 rpm and threading about half that. Slowing it down enough to compensate for your lack of experience is a recipe for extreme frustration. Feel free to try single-pointing for the practice, but be prepared to use a die to get the job done. I've done a lot of single-point threading, and I would use a die.

Learning to thread is much easier on larger parts with better machinability where the rpm's are lower and it's easier to get a finish. Once you've worked out the moves and timing you can progress to more challenging jobs.

You have to learn to walk before you can run.


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## middle.road (Mar 15, 2020)

darkzero said:


> Don't remove those spindle nuts, they are usually for bearing preload. Some people attach a handwheel to the leadscrew, on the right end. I have also seen people make a hand wheel to attach to the ID or OD of the spindle.


The picts show Rev.1, on Rev.2 I was able to add counter balance to it so I can actually run the lathe under power.
I actually did mistakenly engage power once and just with a 1/4" bolt and solid knob it got interesting real quick, really fast.


	

		
			
		

		
	
...


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## Titanium Knurler (Mar 15, 2020)

WobblyHand said:


> If I turn the chuck manually, the leadscrew advances.  How would one attach the handwheel?
> 
> 
> WobblyHand, I attached a handwheel to my PM1236-T by attaching a solid wheel bored centrally to the same size as my spindle bore using a collar attached by an interference fit.  This setup allows you to maintain your spindle bore for longer pieces and the solid wheel helps prevent you from getting entangled in the wheel spokes. It is removable but it pretty much stays on the machine. I use it all the time, especially when doing things like centering a piece in the 4JC. I bet a similar setup will work for your project.  It amazing how one simple project leads to others.  I have a pretty detailed description of it here on H-M.
> ...


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## middle.road (Mar 15, 2020)

Mine: a Yugo cobbled together with a leftover wheel off of a busted up measuring wheel that looks to be a wart on the lathe...

Mike's: a Rolls Royce piece that actually looks to be part of the machine.



Titanium Knurler said:


> WobblyHand, I attached a handwheel to my PM1236-T by attaching a solid wheel bored centrally to the same size as my spindle bore using a collar attached by an interference fit. This setup allows you to maintain your spindle bore for longer pieces and the solid wheel helps prevent you from getting entangled in the wheel spokes. It is removable but it pretty much stays on the machine. I use it all the time, especially when doing things like centering a piece in the 4JC. I bet a similar setup will work for your project. It amazing how one simple project leads to others. I have a pretty detailed description of it here on H-M.


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## mikey (Mar 15, 2020)

I hate guys with pretty machines ...


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## WobblyHand (Mar 15, 2020)

MrWhoopee said:


> I would never try to discourage someone from trying new things or improving their skills.
> 
> However, if the object is to produce that little pin from O-1, I suggest simply using a die and (if necessary) making a very narrow undercut at the shoulder. It is difficult enough to get a decent surface finish threading O-1 at the appropriate cutting speeds. For this diameter, I calculate a turning speed of 1000 rpm and threading about half that. Slowing it down enough to compensate for your lack of experience is a recipe for extreme frustration. Feel free to try single-pointing for the practice, but be prepared to use a die to get the job done. I've done a lot of single-point threading, and I would use a die.
> 
> ...


At some point, I'd like to make that little pin.  I thought I'd use the pin as an excuse to learn SPT.  Managed to do a couple of decent cuts, but my confidence is still low in stopping the threading fast enough.  I get it right most of the time, but not always.  The idea of using a stop and a dial indicator is interesting.  Threading looks like it's a combination of eye/hand coordination, muscle memory and just practice, which I'm willing to do.  

For the heck of it, I'll try using a die as well.  That doesn't mean I'll abandon trying SPT to make the part.  It's an interesting and compact problem.

Walking!  Hah!  I'm still working on the crawling part right now.


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## mikey (Mar 15, 2020)

If you're planning to use tool steel like O-1, you are better off screw cutting the threads. 

A die might work but getting the threads close to a shoulder probably won't happen so you might want to cut a thread relief first. If you try it, use a good, sharp HSS die and start on the side where the threads taper. Once the die has cut a few threads, flip the die over to get as close to the shoulder as you can.


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## MrWhoopee (Mar 15, 2020)

WobblyHand said:


> Threading looks like it's a combination of eye/hand coordination, muscle memory and just practice, which I'm willing to do.



It is definitely all of that. I first learned to single-point in 1979. I still get that nervous feeling in the pit of my stomach on the first engagement of the half-nuts, especially when threading up to a shoulder. (I'm getting old, are my reflexes still up to it?) Once I've made 2 or 3 passes it subsides.


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## Titanium Knurler (Mar 15, 2020)

middle.road said:


> Mine: a Yugo cobbled together with a leftover wheel off of a busted up measuring wheel that looks to be a wart on the lathe...
> 
> Mike's: a Rolls Royce piece that actually looks to be part of the machine.



I bet yours works just fine!  I don’t know about you but I use mine all the time.  I think a handwheel should be standard equipment or at least on option on a lathe.


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## ats1911 (Mar 15, 2020)

darkzero said:


> But if threading a very coarse pitch the thread dial will be moving pretty fast. There is no room for error engaging the half nut on a specific mark when needed.



No kidding. My first for real threading was a 5tpi inside thread in a blind hole. Perfect for a beginner, right? I missed my mark more than once. Even though I was threading 6061 I still clobbered my home made cutter more than once.

Looking back, that hole didn’t really need to be blind and I should have just threaded it toward the headstock. Live and learn....


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## WobblyHand (Mar 16, 2020)

I think I'll make the spindle crank.  Just ordered some stock for the spindle insert.  I have stuff for the handle.

For anyone with a SIEG mini-lathe, LMS has the spindle crank for sale.  Not sure the crank will solve my problem, but hey, it's a tool I can make.  The first of many...  

I will have to remember to unplug the lathe whenever it's attached.  A spindle crank looks like a real arm breaker.


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## royesses (Mar 17, 2020)

I made one for my mini lathe a couple of years ago. I used a chromed wheel from McMaster-Carr and machined the rest out of 4130. I think the angle of the cut was 37°. I think I posted it in the what did you do today thread. Works great for threading.

Roy


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## darkzero (Mar 17, 2020)

royesses said:


> I used a chromed wheel from McMaster-Carr



Does that wheel say Flair Chang Iron on it & did it come with the keyway machined in it already?


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## royesses (Mar 17, 2020)

darkzero said:


> Does that wheel say Flair Chang Iron on it & did it come with the keyway machined in it already?



Yes it is Flair Chang Iron. It did not have the keyway. I bored out the hub as it was a bit small and I broached the keyway. You are good!

Roy


----------



## darkzero (Mar 17, 2020)

royesses said:


> Yes it is Flair Chang Iron. It did not have the keyway. I bored out the hub as it was a bit small and I broached the keyway. You are good!
> 
> Roy



Thanks Roy. Oh no I was wondering cause I put the same handwheels on my mill & for the fine feed too. I had no idea Mcmaster sold them, I got mine from Grizzly when they used to sell them.


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## royesses (Mar 17, 2020)

darkzero said:


> Thanks Roy. Oh no I was wondering cause I put the same handwheels on my mill & for the fine feed too. I had no idea Mcmaster sold them, I got mine from Grizzly when they used to sell them.
> 
> View attachment 316978
> View attachment 316979
> ...


I may be wrong about where I got it. Old timers disease. Sorry for the miss information about where I got it.
I just looked it up in my emails you are right on it was Grizzly:
(1)    H3190           CAST IRON HANDWHEEL 8"

(1)    H3205           CHROMED HANDLE 4" X 3/8"

You do some beautiful work Will. Your attention to detail is extraordinary.

Roy


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## darkzero (Mar 17, 2020)

royesses said:


> I may be wrong about where I got it. Old timers disease. Sorry for the miss information about where I got it.
> I just looked it up in my emails you are right on it was Grizzly:
> (1)    H3190           CAST IRON HANDWHEEL 8"
> 
> ...



Haha, ah damn, I had thought I found a new source for them through you. But that's ok, I doubt the ones on my mill will ever need replacing.

Thanks Roy, I'm just a beginner hobbyist.  Your handwheel came out great. I like the angle split shaft attachment or whatever it's called. I probably would have never thought of that. That's a great idea, reminds me of when I used to wrench on my bicycles (handlebar stem) when I was a kid.


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## royesses (Mar 17, 2020)

darkzero said:


> Haha, ah damn, I had thought I found a new source for them through you. But that's ok, I doubt the ones on my mill will ever need replacing.
> 
> Thanks Roy, I'm just a beginner hobbyist.  Your handwheel came out great. I like the angle split shaft attachment or whatever it's called. I probably would have never thought of that. That's a great idea, reminds me of when I used to wrench on my bicycles (handbar stem) when I was a kid.


Thanxs, Will.  Yes Will, it is the same as a bicycle handle bar, I think it's called a stem quill. I looked up a patent and they had researched the best angle. They said 34° to 38° was the most efficient angle. It never slips in the spindle and instantly comes out when the through bolt is loosened. 

Roy


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## royesses (Mar 17, 2020)

Will, Amazon still sells the Grizzly wheels. . The 6" is only $14.95.


			Amazon.com
		



8" wheel"




__





						Grizzly H3190 Cast Iron Handwheel, 8-Inch - Table Saw Accessories - Amazon.com
					

Grizzly H3190 Cast Iron Handwheel, 8-Inch - Table Saw Accessories - Amazon.com



					www.amazon.com
				




Roy


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## WobblyHand (Mar 17, 2020)

royesses said:


> I made one for my mini lathe a couple of years ago. I used a chromed wheel from McMaster-Carr and machined the rest out of 4130. I think the angle of the cut was 37°. I think I posted it in the what did you do today thread. Works great for threading.
> 
> Roy
> 
> ...


What is the overall length of the part that is inserted in the spindle bore?  5 inches?  I have some stock now and am trying to figure out how it should fit.  It looks like there is a shoulder that is machined to the spindle bore for registration, and the internal part is smaller in diameter.  I don't have a sense of how critical the dimensions are.  Any rules of thumb?


----------



## WobblyHand (Mar 17, 2020)

Tried 32TPI SPT on 0.5" 12L14 stock, that went ok, although the fine pitch threads did have some debris in them.  Was able to clean out most of the debris with a file card.  

With that under my belt, I did a practice run of single point threading 8-32 in O1.  First I turned down the major diameter to 0.160".  I then unplugged the lathe.  I put in a lathe stop.  Manually turning the chuck, (haven't built the spindle crank yet) cut threads until I hit the stop.  I went 0.005" per cut.  Threads are not showcase quality.  Actually, they're horrible.  The threads looked ok for most of the cutting.  An 8-32 nut was my fit gauge. 

While cutting, there was a slight jerk and a pop.  Later on I found that the tip of the HSS tool bit had chipped off.  Is this a sign of work hardening of the O1, or just a latent fault in the tool bit?   Will have to regrind the tool.  Even so, the nut fits and threads fully to the shoulder.  The threads are kind of loose fitting, I assume that is because I cut too deep.  (I guess I didn't calculate out the cosine factor out correctly.)  It was an interesting exercise (manually spinning the chuck with my hand), but a crank is necessary if I'm ever going to do hand cutting again.

Pictures to follow.  Have to go take them.


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## mikey (Mar 17, 2020)

Did you grind a tiny flat at the tip of your tool after you ground it? If you don't, that sharp tip will fracture right off. You only need a tiny flat, maybe 1/64" across, but that will allow you to cut threads in most materials without any issues.


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## WobblyHand (Mar 17, 2020)

mikey said:


> Did you grind a tiny flat at the tip of your tool after you ground it? If you don't, that sharp tip will fracture right off. You only need a tiny flat, maybe 1/64" across, but that will allow you to cut threads in most materials without any issues.


I didn't grind a flat.  Guess that's what happened.  What angle is the flat relative to the top surface of the tool?  Or is it along the whole edge?  Hmm, don't know the proper terminology to describe this.


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## darkzero (Mar 17, 2020)

royesses said:


> Will, Amazon still sells the Grizzly wheels. . The 6" is only $14.95.
> 
> 
> Amazon.com
> ...



Thanks Roy. Says sold & ships from Grizzy. Looks like Grizzly does still sell them & found em on their website. I could of sworn the last time I looked I couldn't find them. But then again that was when they had just changed their website format.


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## WobblyHand (Mar 17, 2020)

Some pictures.
0.480-32 threads in 12L14 - non fractured tool bit.


Fractured tip of 5/16 SPT tool bit.


Ugly, embarrassing 8-32 threads in O1



Side view of fractured tip of tool bit.  As you can see, the tip didn't break, but just below fractured.


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## royesses (Mar 17, 2020)

WobblyHand said:


> What is the overall length of the part that is inserted in the spindle bore?  5 inches?  I have some stock now and am trying to figure out how it should fit.  It looks like there is a shoulder that is machined to the spindle bore for registration, and the internal part is smaller in diameter.  I don't have a sense of how critical the dimensions are.  Any rules of thumb?



My mini lathe has an extension screwed onto the spindle that prevents chips from falling into the change gears. That is why the diameter is 1.001 just before the wheel stop. The through bolt is 3/8" x 16TPI x 4.75". Thread is about 2" just need enough threads to wedge it tight inside spindle. The bore in the non threaded portion needs to allow the through bolt room to move as the wedge comes up.
Here is a poor sketch of the dimensions:


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## royesses (Mar 17, 2020)

darkzero said:


> Thanks Roy. Says sold & ships from Grizzly. Looks like Grizzly does still sell them & found em on their website. I could of sworn the last time I looked I couldn't find them. But then again that was when they had just changed their website format.



That has happened to me before. Since I had the part numbers it came up right away on Amazon.

Roy


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## WobblyHand (Mar 17, 2020)

royesses said:


> My mini lathe has an extension screwed onto the spindle that prevents chips from falling into the change gears. That is why the diameter is 1.001 just before the wheel stop.
> Here is a poor sketch of the dimensions:
> View attachment 317084


Thanks!  I was trying to figure out how much was inside the spindle, mostly so I could determine overall length how to drill it.


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## royesses (Mar 17, 2020)

WobblyHand said:


> Thanks!  I was trying to figure out how much was inside the spindle, mostly so I could determine overall length how to drill it.


If you need more information just let me know. I drilled it to tap the 3/8" x 16TPI and then cut it at an angle then drilled out the remaining portion to 1/2" If you don't have a broach and mill you can pin the hand wheel to the quill since there is no need to remove the handwheel from the quill in normal operation.

Roy


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## BtoVin83 (Mar 17, 2020)

Just out of curiosity why don't you'all learn to cut threads like about every other machinist. The only time we would thread to a groove is for bearing lock nuts. If  I could learn it just about everybody can too.  When you master it the fear goes away and you just thread stuff.


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## mikey (Mar 17, 2020)

You grind it at the very tip of the tool. The angle follows the slope of the tool at the front so that the flat is even, top to bottom.


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## WobblyHand (Mar 17, 2020)

BtoVin83 said:


> Just out of curiosity why don't you'all learn to cut threads like about every other machinist. The only time we would thread to a groove is for bearing lock nuts. If  I could learn it just about everybody can too.  When you master it the fear goes away and you just thread stuff.


1. Rank Beginner.  Older than I'd like to admit.  Reflexes not like they were 40 years ago.
2. 5 threads to a stop.  0.18" long
3. Have no issue with threading 1".  Lots of time between starting and stopping
4. Beginner


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## WobblyHand (Mar 17, 2020)

mikey said:


> You grind it at the very tip of the tool. The angle follows the slope of the tool at the front so that the flat is even, top to bottom.


Thanks.  That chip off the tool is about 1/64" wide.  So I'll try to flatten the whole edge.  So this looks like a honing sort of thing, rather than setting up the belt sander again.


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## brino (Mar 17, 2020)

@WobblyHand 

I just gotta compliment you on the great close-up pictures you are posting.
Both the pictures of your threads and the tool tip.
The detail you've captured is like being there.....with a magnifying lamp and my good eye!

Obviously your hands are NOT too wobbly!  

-brino


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## WobblyHand (Mar 17, 2020)

Thanks.  Used magnification (zoom) for the pictures AND rested my hands and phone on the desk.  Oh yeah, the phone does help a bit with image stabilization.  Otherwise, everything would all be a blur.


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## Tozguy (Mar 17, 2020)

It looks like your tool could use some more side relief to accommodate the helix angle. I will try to take a picture to illustrate it.


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## WobblyHand (Mar 17, 2020)

Tozguy said:


> It looks like your tool could use some more side relief to accommodate the helix angle. I will try to take a picture to illustrate it.


Thanks.  A picture, or figure would be awesome.  This is a stock LMS threading bit.  I just honed the faces of the bit.  (And forgot to put on a flat on the tip)  I haven't ground my own threading bit yet, just a key-stock example.


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## Tozguy (Mar 17, 2020)

This might show what it looks like. There has to be more relief on one side which makes the front edge slope at an angle (of at least as great as the helix angle of the threads).


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## WobblyHand (Mar 17, 2020)

Ok.  I see what you mean now.  The LMS tool has little or no relief.  So does my example key-stock.  How does one get the relief? Not sure how I'd grind the tool to get this better match to the helix.  @mikey have any insight to get a little more "helix" correction?


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## mikey (Mar 17, 2020)

WobblyHand said:


> Thanks.  That chip off the tool is about 1/64" wide.  So I'll try to flatten the whole edge.  So this looks like a honing sort of thing, rather than setting up the belt sander again.



Yes, just use your diamond stone and hone it on.


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## mikey (Mar 17, 2020)

WobblyHand said:


> Ok.  I see what you mean now.  The LMS tool has little or no relief.  So does my example key-stock.  How does one get the relief? Not sure how I'd grind the tool to get this better match to the helix.  @mikey have any insight to get a little more "helix" correction?



First, the relief angles on a HSS threading tool makes a difference in how clean the threads are. Standard relief angles (the angles under the cutting edges) are between 5-8 degrees. That's okay, they work. However, my tests suggest that a 15 degree relief angle produces lower cutting forces and much cleaner threads. My threads have almost no burrs so it seems to work for me. If your tool is not working well, try increasing the relief angles and put that flat on. I bet it will cut better for you.

As far as helix angles go, I would worry about it if I was using carbide inserts to cut threads. The smaller the diameter of the work and the greater the number of TPI, the more helix angle matters with inserts because of the geometry of the insert itself. With HSS tools that have zero rake on top, this is much less of a concern so I personally do not alter the grind to compensate for helix angles. I've cut threads down to 4-40 with no issues at all so I don't worry about it.


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## WobblyHand (Mar 17, 2020)

The LMS tool is not cutting clean threads.  Or at least not for 32 TPI.  That's after honing the three faces.  Unfortunately, I forgot to flatten the tip.  So, I'll try increasing the relief angle by grinding a new bit.  I have a key-stock template I ground, (from your excellent tool grinding thread) but didn't get around to grinding it in HSS.  Sounds like I need to set up the belt sander and vacuum cleaner again!


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## Tozguy (Mar 18, 2020)

Helix angles will vary depending on diameter and threads per inch. When single point cutting threads it is important to be conscious of the helix angle if only to realize its a factor. If the relief angle on the tool is routinely generous then chances are you do not need to 'worry' about helix angles. But if your thread cutting tool does not have enough relief then it will rub or cut poorly. The reason to increase relief from 7-8 degrees to 15ish for cutting threads as mentioned above is largely to accommodate the helix angle and still have some relief at the cut.


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## Tozguy (Mar 18, 2020)

This is a handy calculator for any thread work and it includes lead angle (or helix angle).
So you don't have to do the trig calculations yourself 





__





						UN imperial screw thread calculator
					






					theoreticalmachinist.com


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## mikey (Mar 18, 2020)

Tozguy said:


> Helix angles will vary depending on diameter and threads per inch. When single point cutting threads it is important to be conscious of the helix angle if only to realize its a factor. If the relief angle on the tool is routinely generous then chances are you do not need to 'worry' about helix angles. But if your thread cutting tool does not have enough relief then it will rub or cut poorly. The reason to increase relief from 7-8 degrees to 15ish for cutting threads as mentioned above is largely to accommodate the helix angle and still have some relief at the cut.



I totally agree, Mike. The issue with helix angles is the rubbing that occurs when you run out of relief angle with a standard or inserted carbide tool. We had a brief discussion about it here. The thing about grinding tools for helix angle is that the helix angle changes for each and every thread and if we ground a tool for every thread we cut in a hobby shop we would have a lot of tools on the shelf. I ran my own tests and *for me*, a standard 60 degree tool with 15 degree relief angles works fine for all the standard 60 degree threads I am likely to cut in my shop. I have had no rubbing in threads from 4-40 to 3/4-16;  well, at least my thread form is good, burrs are minimal and fits are good. 

I suppose I could go back to our model tools thread and go into all of this helix angle business. I didn't do it because excessive detail tends to confuse new guys who have enough on their plate just learning to grind a basic tool. A 15 degree relief angle works without having to go into why it works.


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## mikey (Mar 18, 2020)

I went back and read my own thread that I linked to above and wanted to mention the suggestion by @carlquib that we can use a ROUND threading tool and angle it in the tool holder to suit the helix angle. I think this is a novel and enlightened idea that I must try one day, especially if I have to do a multi-start thread (which I haven't had to do yet). 

The hardest thing about machining is to keep things simple. I like simple ... but sometimes it isn't about what I like.


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## WobblyHand (Mar 18, 2020)

@mikey, if you do go further into _helix_ stuff, put it in the model tools thread.  I'd want everyone to be able to find it.  And, yeah, when I first read the that model tools thread, it was confusing the first time through.  But, with a combination of reading and doing (grinding and threading) things have become much clearer.  Speaking for myself, experiencing a non-optimal tool grind  motivates me to do it better.  The grind I was using made burr filled and almost muddy threads in 3 different materials, aluminum, pvc and 12L14.  There's quite a difference in angle between the LMS grind and yours.  I measure about an 80 degree angle with the LMS and about 62.3 degrees with yours.  So the tip falls away from the thread a lot faster with your grind.  

Got a little sidetracked designing an adapter plate for leveling casters for my lathe stand.  Basement floor isn't level.  Design is done. Template made.  Got to cut some metal, after the tool grinding.  For the peanut gallery:  My wife was listening to me for a while, stopped me and said, "If I had a dollar for everytime you said this would be easy with a milling machine, I'd be a millionaire."  

Back to tool grinding...  Final location for my belt sander isn't finished, so I'll make a temporary setup.  (No power or lights there!)  I'll grind a proper threading tool somehow tonight.


----------



## mikey (Mar 18, 2020)

WobblyHand said:


> @mikey, if you do go further into _helix_ stuff, put it in the model tools thread.  I'd want everyone to be able to find it.  And, yeah, when I first read the that model tools thread, it was confusing the first time through.  But, with a combination of reading and doing (grinding and threading) things have become much clearer.  Speaking for myself, experiencing a non-optimal tool grind  motivates me to do it better.  The grind I was using made burr filled and almost muddy threads in 3 different materials, aluminum, pvc and 12L14.  There's quite a difference in angle between the LMS grind and yours.  I measure about an 80 degree angle with the LMS and about 62.3 degrees with yours.  So the tip falls away from the thread a lot faster with your grind.
> 
> Got a little sidetracked designing an adapter plate for leveling casters for my lathe stand.  Basement floor isn't level.  Design is done. Template made.  Got to cut some metal, after the tool grinding.  For the peanut gallery:  My wife was listening to me for a while, stopped me and said, "If I had a dollar for everytime you said this would be easy with a milling machine, I'd be a millionaire."
> 
> Back to tool grinding...  Final location for my belt sander isn't finished, so I'll make a temporary setup.  (No power or lights there!)  I'll grind a proper threading tool somehow tonight.



Wives have a way of coming up with really inspired snide one-liners ... must be an X-linked thing.  

Yeah, tool grinding can be really confusing. I tried to make it as simple as I could because believe me, there is a lot more to tool geometry than I put in those discussions. Keep trying and it will eventually become easier to visualize and do. When you feel comfortable with it, try altering your tool angles to better suit your needs.

As for taking up Helix angles in our model tools thread, I'll think about it. I won't say much beyond the thread I linked to above so I'm not sure it would make a difference.


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## Tozguy (Mar 18, 2020)

Tool grinding is almost as difficult to understand as women are....but both are totally worth the suffering.
As Tim the 'tool man' once said, 'women can make you oh so happy but can also make you oh so sad.'
Same as tool grinding.


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## MrWhoopee (Mar 20, 2020)

WobblyHand said:


> For the peanut gallery:  My wife was listening to me for a while, stopped me and said, "If I had a dollar for everytime you said this would be easy with a milling machine, I'd be a millionaire."



If she had a dollar for every time you said this would be easy with a milling machine, she could buy you one.


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## Tozguy (Mar 20, 2020)

Sounds to me like she wants you to stop talking about it and do it.


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## MrWhoopee (Mar 20, 2020)

I'd like to offer a second opinion on the problems with the part in question.
While helix angle is important, on a part with a diameter this small and pitch this fine, I think the major problem lies elsewhere. 

First, O-1 has pretty low machinability making it difficult to get a decent finish under less than optimum conditions. Depending on the application, I would recommend using Stressproof or ETD150, both of which are available on eBay. ETD150 is equivalent in hardness and strength to heat treated 4140 with much better machinability. 

Second,  I would suggest that the ragged finish and chipped tool are both related to the low speed and stop and go nature of turning the spindle by hand. While I can't adequately explain the physics, higher speeds cause the material to shear more cleanly and consistently, producing a better finish. In addition, at higher speeds, the metal actually shears ahead of the cutting edge reducing the stress on the cutting edge. We all know that one of the best ways to chip carbide is to stall it in the cut. While HSS is more forgiving, the same conditions exist. Also, a slight reverse movement is almost certain to chip a sharp tool nose that is buried in the cut.

JOMO


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## WobblyHand (Apr 2, 2020)

Sorry to keep you all in suspense  .  Things have taken quite a bit longer than expected.  So I bought the hand wheel from Grizzley.  Then made the spindle section out of 12L14.  I made a small shoulder so that the key wouldn't fall out.  I haven't made the keyway, but it is threaded at the right side, and ready to cut.





I had no way to hold the lathe locked (to make the keyway) so I just built a lathe lock.  I was so proud of myself, but screwed it up at the last moment, since I forgot to account for the diameter of the screw heads holding down the key.  I'll turn the screw heads down until it fits.  It does hold the spindle stationary.  The two lower screws M5 on the right hand and left hand side screw into the lathe headstock.  The large semi-circle was cut out by with a die grinder using a carbide.  The upper bite mark on the left hand side also was done with a slightly smaller carbide burr.  The chisel point is just some stock that I ground down using the belt sander.  I need to trim the key to length still.


I used some transfer screws to get the holes to line up to the lathe and the keystock.  These are pretty cool.   Still waiting on some 1/8" cut off blades.  The parting blades will be used to cut the keyways on the spindle and wheel.

The only thing I don't have a handle on (literally) is how to clamp the handwheel down to bore it.  I will have to improvise something. I think I have to clamp from the inside of the wheel, as there isn't much clearance on the outside before hitting the ways.  A mini-lathe is limiting for something like this.  I don't have the luxury of clamping it like @darkzero did.  Clamping on the inside seems to have some challenges as the features seem to get in the way of the slots.  Can't fit a full 3/8" bolt through both holes because the balance is thrown off.


Slowly getting there.


----------



## WobblyHand (Apr 2, 2020)

Ok, I was embarrassed about the lathe lock, so worked on it.  Turned down the screw heads so they would fit next to each other. Then cut off the key and ground it to the edge of the main piece.  Rounded the corner so it wouldn't bite me.


Installed on the lathe.  Fits perfectly!  Lathe is locked.  Someday might make a better key, but this came out well.  If the key is removed, the lathe spins freely.


Still pondering how to clamp the handwheel.  Need to make some hold downs and spacers.  A standard hold down (I have a 3/8" kit) is way too large to fit on the inside of the wheel.  5/16 studs might fit through the undulations in the wheel.


----------



## brino (Apr 2, 2020)

WobblyHand said:


> Still pondering how to clamp the handwheel. Need to make some hold downs and spacers. A standard hold down (I have a 3/8" kit) is way too large to fit on the inside of the wheel. 5/16 studs might fit through the undulations in the wheel.



You just need to open up the bore right? ......or was it cutting the keyway?
Either way, is there any reason you can't just grab the backside round hub in the 3 or 4-jaw chuck?

-brino


----------



## WobblyHand (Apr 2, 2020)

@brino, I need to partially bore out the hub.  And cut a keyway.  I want to sink the shaft into the hub so that the top of the machined spacer is level with the back of the hub.


The top diameter of the shaft is 0.795".  The ring diameter is 0.998", and the bottom piece is 0.900".  (1" stock)  The top surface of the ring is to be flush with the hub surface.  The ring will retain the key from falling out.  I will then cut a key in the hub, and one in the shaft (up to the ring, but not through it).  The bottom of the hub has a 1/4" hole, I need to bore it to clearance for 3/8".  So I can't simply bore it through from the other side

Here is a simple sketch that I just made.  I left out the key.  It is cut in the 0.750" diameter section of the shaft and the hub.  


All this is to say, that I think it's better to hold the wheel to the plate in this current orientation.  I did look at using the jaws of the 3J chuck in an opening fashion.  Sorry, I'm at a loss for the right terminology.  When I first looked at it, the jaw height wasn't quite high enough to have enough grip.  Maybe have to look at it again, to get a different perspective.  Perhaps there is a better simpler way to do this.  That's why I'm posting.


----------



## WobblyHand (Apr 3, 2020)

Well, , holding the handwheel was easy.  All it took was a night's sleep to figure it out. Switched jaws on the 3J chuck and opened the jaws. The wheel's not quite running true, but it's ok.  It was true on initial clamping, but it shifted when I tightened (actually loosened) the jaws.   Slight vibration when running.  Not quite enough vibration to make me want to balance it.

Bored out the 3/8 clearance hole clear through the hub with a Micro 100 boring bar BB-2301600.  Could have used a drill, but I was afraid a larger drill might grab and rip the wheel off the chuck.  Cast iron is messy!  Lots of little bits of cast iron flying in the air, getting on everything, including my face.  Can't wait 'til I hog out the hole, that's going to be a mess! Probably change the bar to a standard boring bar for hogging out.  That carbide bar just seems so delicate.  It's waiting for me to make a mistake...  Back to boring boring.


----------



## WobblyHand (Apr 3, 2020)

My goodness what a mess.  Even after cleaning everything up with a vacuum, things are still messy.  I cleaned the ways with a brush, and some wipes, and still the cast iron is everywhere.  Next, using the lathe lock, managed to cut a key slot using an 1/8" cut off blade.  Each cut was no more than a few thousandths in depth at a time.  Sometimes only a thousandth at a time.  The lathe carriage handle really doesn't have much mechanical advantage, so it was pure grunt work.  Some cuts just really were difficult.  About 80 cuts later we have:


That's it for today.  Tomorrow the shaft will have a matching slot cut. Then I'll fit the key.  The key might need a little polishing to fit, as it is oversized.  Dunno why I bought oversized keystock, glutton for punishment?


----------



## brino (Apr 4, 2020)

It must have been a pain to get that running true since you had to grab between the handle flutes with the outside jaws on the chuck.
But you did it.

It looks perfect from here!
Nice job.

Thanks for sharing it.
-brino


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## WobblyHand (Apr 6, 2020)

Done with the wheel, save for a little touch up and the right size bolt.  The small flange got dinged when it was in the vise to saw.  I had wrapped it in tape and used aluminum jaws, but somehow it got damaged.  Here's a couple of pics of the handwheel using a 5 inch stud.  The stud will be replaced with a socket head cap screw.  Have to say, this was an interesting adventure.  Cutting keyways by hand is something I'll remember in a less than fond way.  The key was oversized, so it had to be lapped and ground it to fit.   Can't believe how much time there is in this simple thing.




Hmm, so where was I? 

Oh yeah, threading.  A new threading tool in HSS was ground, using mikey's angles.  Added a flat along the edge.  I have some 12L14, O1, and 4140 in the right size.  For some reason, didn't get 1144, guess it slipped my mind.  Maybe next order. Seems like 1144 would be my best bet for strength + machinability.  This pin is in relatively high stress as it is a pump pivot.  The pin is held at both ends and the pump arm pushes against the middle.  I've had some "commercial" pins bend.

Think I'll practice with 12L14, to get the idea, and eventually make it in 1144.


----------



## royesses (Apr 6, 2020)

WobblyHand said:


> Done with the wheel, save for a little touch up and the right size bolt.  The small flange got dinged when it was in the vise to saw.  I had wrapped it in tape and used aluminum jaws, but somehow it got damaged.  Here's a couple of pics of the handwheel using a 5 inch stud.  The stud will be replaced with a socket head cap screw.  Have to say, this was an interesting adventure.  Cutting keyways by hand is something I'll remember in a less than fond way.  The key was oversized, so it had to be lapped and ground it to fit.   Can't believe how much time there is in this simple thing.
> View attachment 319861
> View attachment 319862
> View attachment 319876
> ...



Great job WobblyHand!  Looks good and I bet it works good too. Really comes in handy when cutting threads with a tap or die. 

Roy


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## GunsOfNavarone (Apr 6, 2020)

darkzero said:


> How close do you need to get to the shoulder? Does the part require no thread relief between the thread & shoulder? With practice you should be able to get it. I can thread into a 1/16" wide thread relief no problem disengaging the half nut without any aid.
> 
> By aid what I mean is a dial indicator. When I single point threads I set up a dial indicator to read zero 10 thou off a shoulder or blind hole. I use the modified flank method for threading so to set the dial indicator after setting tool position off the work, I retract the cross slide, advance the compound to the full depth required for the thread pitch being cut, then move the carriage so the cutter bottoms out on the shoulder or the blind hole. Then I set the dial indicator for the carriage +.010. I set the 0 mark at 12:00, the needle starts moving from 6:00 on my DI.
> 
> ...


@darkzero ' not sure the method you speak of..ut I wanna know more! Do you need a reverse tumbler to execute what your talking about?


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## WobblyHand (Apr 7, 2020)

Tried a piece of 12L14 with the handwheel setup.  Boy, that handwheel really helped!  Made it a lot easier.  Was able to make some decent threads.  They are better than the originals.  They ought to be, since I'm using 12L14.  (I bought some more of these pins - got to keep the economy going.)  Looking carefully at the originals, it is obvious they were single point threaded.  And there is no groove, the threads just start.  (Original on top, 12L14 on bottom)


I then tried turning the original 12L14 threads (hex stock - from early in this thread) down and recut them under power.  This is with the threading tool I ground.  The threads are better quality than with the LMS threading bit, but there are some burrs.  Looking carefully at my tool, I see the tip is cracked off.  Now, I put in a flat on this tool along the edge.  The flat can't be too wide, or I can't do 32 TPI threads.


I seem to be breaking off the tip.  What could cause this?

I'd like to make a relief for the thread.  What kind of tool is used for this?  Could one grind a parting tool thinner?  (Have a spare blade)  The _relief_ that is there was just keeping the threading tool in the same place, but that doesn't create the square shoulder that it should have.


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## GunsOfNavarone (Apr 7, 2020)

WobblyHand said:


> Tried a piece of 12L14 with the handwheel setup.  Boy, that handwheel really helped!  Made it a lot easier.  Was able to make some decent threads.  They are better than the originals.  They ought to be, since I'm using 12L14.  (I bought some more of these pins - got to keep the economy going.)  Looking carefully at the originals, it is obvious they were single point threaded.  And there is no groove, the threads just start.  (Original on top, 12L14 on bottom)
> View attachment 320105
> 
> I then tried turning the original 12L14 threads (hex stock - from early in this thread) down and recut them under power.  This is with the threading tool I ground.  The threads are better quality than with the LMS threading bit, but there are some burrs.  Looking carefully at my tool, I see the tip is cracked off.  Now, I put in a flat on this tool along the edge.  The flat can't be too wide, or I can't do 32 TPI threads.
> ...


SO you are threading towards the chuck? Does your lathe have a break or are you disengaging the half nut? I was told by many not to disengage, just stop, pull the compound out and reverse then restart moving the compound back in....The slowest my lathe turns (currently) is 150 rpm unless I'm doing 100 tpi (joking) its just moving too quick to thread 1/4" like you did AND no relief.


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## WobblyHand (Apr 7, 2020)

I was threading towards the chuck.  The half nut was disengaged at the end.  For the 8-32 threads shown, I was using a hand crank that I just made.

For the 1/2-32 threads that I was doing under power, I did cut a thread relief.  For that I waited until the dial came to 1 and engaged the half nuts.  At the thread relief I disengaged.  There was 1/2" length of threads so it was easier to time.  

I haven't tried threading away from the chuck yet.  For that I need to grind a left hand threader bit.  I'd like to try that and mount it upside down.  Maybe I'll try that tomorrow.


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## GunsOfNavarone (Apr 7, 2020)

I can get clean threads (this was straight off the lathe-didn't even clean it up), perfect fit...but even this small of a relief, I had some abrupt stops up against the work piece. Guess I gotta work on that. I was trying to follow DarkZero's technique with the DI...couldn't really get the jist. Is that what you're doing? I will say, my DRO I don't have the ability to track so many things going on, I really don't have the ability to multi task like that.


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## GunsOfNavarone (Apr 7, 2020)

WobblyHand said:


> I was threading towards the chuck.  The half nut was disengaged at the end.  For the 8-32 threads shown, I was using a hand crank that I just made.
> 
> For the 1/2-32 threads that I was doing under power, I did cut a thread relief.  For that I waited until the dial came to 1 and engaged the half nuts.  At the thread relief I disengaged.  There was 1/2" length of threads so it was easier to time.
> 
> I haven't tried threading away from the chuck yet.  For that I need to grind a left hand threader bit.  I'd like to try that and mount it upside down.  Maybe I'll try that tomorrow.


Yeah, I wonder if the fracturing tool and the rough threads can both be attributed with the very slow, even stop and go technique of the hand crank?


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## WobblyHand (Apr 7, 2020)

Nope no DI.  I'm just a beginner, I don't have all the tooling built up.  I don't have a DI holder that I can attach to the ways or the carriage.


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## WobblyHand (Apr 7, 2020)

GunsOfNavarone said:


> Yeah, I wonder if the fracturing tool and the rough threads can both be attributed with the very slow, even stop and go technique of the hand crank?


I can say it's slow, but, not really stop and go.  It's pretty easy to crank smoothly.  Whether this slow speed causes tool fracture and rough threads, I leave that up to those who are more knowledgeable than myself.


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## WobblyHand (Apr 12, 2020)

Actually, that last set of threads was threading going straight in, not modified flank.  Maybe that's why they weren't that clean.  I forgot what the angle was and was too lazy to go online to look it up.  I'll have to print out a picture and hang it up next to the lathe.

Still don't know why the tip of the tool is breaking off.  It's discouraging since it take me all afternoon to hone a single tool.  @mikey What could cause the tip to break off?  I am putting a flat along the whole edge.  I was spt'ing  12L14 when it broke.


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## mikey (Apr 12, 2020)

Not sure. The only time I've ever cracked off the tip of a threading tool is when I didn't put a flat at the tip. The flat should follow the front V of the tool, from top to bottom, and it only needs to be about 1/64" wide. 

Might help to see a pic of your tool.


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## WobblyHand (Apr 12, 2020)

mikey said:


> Not sure. The only time I've ever cracked off the tip of a threading tool is when I didn't put a flat at the tip. The flat should follow the front V of the tool, from top to bottom, and it only needs to be about 1/64" wide.
> 
> Might help to see a pic of your tool.


Post #100 of this thread.  If you need a better photo, I can try to take another one.
Looking at the tool flat, it seems the width is less than a 1/64" , maybe half of that?  It's less than a 1/100", at least if I rest the scale on top of the flat.  Looks like more flattening is necessary.  Had to look at it under an 8X magnifier, eyes may have deceived me earlier.


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## mikey (Apr 12, 2020)

Sorry I missed that photo. 

Okay, the flat has to be across the width of the tip. These are my threading tools. The flat is across the width of the tip and is most visible on the larger tool on the left. The flat you see is about 1/64" across on the tool on the left. It is half that on the tool on the right.




Let me know if this is at all unclear.


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## WobblyHand (Apr 12, 2020)

I understand.  Well, here's the latest pictures.



This is a lot wider than I had it before.  Hopefully it won't crack now.  There is a little taper on the width from top to bottom, hope that's ok.  I honed the 3 faces after I did the flat.  (Right, left and top.)  Now that I've followed the instructions...  things should be better.  Some folks need to learn the hard way, I guess.  (Raises hand!)


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## mikey (Apr 12, 2020)

Yup, you got it. Should be okay now.

Edit: I meant to tell you that you did a nice job grinding that tool! Threading tools are harder to grind because the geometry has to be precise. Not everyone manages it quite as well as you did here - good job!


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