# Single Point Threading on a PM-1030V?



## erikmannie (Feb 15, 2020)

I had hoped to do better than a thread title with a question mark in it! That means that I haven’t figured this out yet.

I definitely know how to do single point threading on a lathe. At school, we had the big domestic machines where you used the TPI chart in order to find out where to put the levers to set the TPI.

The 1030V has a chart on it which I do not yet understand even though I have read the manual twice.

To me, the question was which change gears (if I am using that term correctly) came installed in the machine. I figured that out by physically looking at the gears when I had the door open to change from low to high range.

I am on my phone now, but I will get on a laptop and upload the chart when I get on a PC.

My main question is why they have an “H” listed next to the bottom (largest) gear. This is why I put the lathe into the high range, but this did not change the thread pitches that I was cutting. Also, as you know, the spindle RPM did not change the thread pitch.


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## erikmannie (Feb 15, 2020)

My plan today (which was not a success) was to use the A, B and C speeds (the knob on the headstock) to see what TPI that I would cut. The A and C choices cut threads with TPIs that were in excess of 100 TPI, so I don’t know what went wrong there.

The B selection (which rotates the leadscrew the fastest cut either 32 or 36 TPI (I don’t remember), but that TPI value did not correspond to anything in a B row in the chart.

I found it interesting that the spindle speed had no effect on the TPI. So I guess I shouldn’t have been surprised that putting into high range still resulted in the 32 (or 36?) TPI mentioned above.


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## erikmannie (Feb 15, 2020)

So hopefully somebody can give me a clue about how to proceed. I am going to go back and read the manual yet again.


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## erikmannie (Feb 15, 2020)

This is the chart that I have yet to understand:


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## middle.road (Feb 15, 2020)

Have got the manual off of P-M's site, now,
Step 1: post up a picture of the chart(s) off of your machine.
*EDIT* NVM....  (hehe)


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## erikmannie (Feb 15, 2020)

Posting more pictures now...

I wonder what this is a picture of. Is that a tool bit cutting a 45 degree chamfer? I imagine that it is a reference to the power feed speed for the carriage and cross slide. What are the black ovals supposed to represent?


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## middle.road (Feb 15, 2020)

erikmannie said:


> Posting more pictures now...
> 
> I wonder what this is a picture of. Is that a tool bit cutting a 45 degree chamfer? I imagine that it is a reference to the power feed speed for the carriage and cross slide. What are the black ovals supposed to represent?
> 
> View attachment 313721


One shows you the speed while feeding with the saddle - left to right
The other is while facing with the cross slide - in and out. 
At least that's my interpretation of them.


Jump into the chat room.


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## erikmannie (Feb 15, 2020)

Here are some pictures of the fun. If at all possible, I turn between centers for the historical experience..


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## erikmannie (Feb 15, 2020)

And more pictures which are self explanatory:


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## mmcmdl (Feb 15, 2020)

I would change your set-up a bit , and this is only my opinion not knowing what lathe you're using . I myself would keep your tailstock quill in as far as possible , and have my tool hang out a little for clearance . That overhang in the tailstock will introduce chatter and possibly even a tapered part . A cnc reduced center would buy you some tool clearance . This is only my opinion , take it with a grain of salt .


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## francist (Feb 15, 2020)

I think I remember the first part of this question from a while ago, and if I recall correctly the “H” represents a spacer which, depending if it it is in the front position or the rear position, affects which gear wheel engages the lead screw. Why they chose to use an “H” wasn’t clear, but the most popular guess was that it was short for “Hempty”


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## erikmannie (Feb 15, 2020)

middle.road said:


> Have got the manual off of P-M's site, now,
> Step 1: post up a picture of the chart(s) off of your machine.
> *EDIT* NVM....  (hehe)





mmcmdl said:


> I would change your set-up a bit , and this is only my opinion not knowing what lathe you're using . I myself would keep your tailstock quill in as far as possible , and have my tool hang out a little for clearance . That overhang in the tailstock will introduce chatter and possibly even a tapered part . A cnc reduced center would buy you some tool clearance . This is only my opinion , take it with a grain of salt .


Great advice! That is a slim body live center https://www.precisionmatthews.com/shop/lc-mt2-slm/ , and I could move the location of the compound so that I could draw in the tailstock quill. The DRO scale makes the cross slide wider.


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## mmcmdl (Feb 15, 2020)

Every little detail helps in lathe work , especially in shaft work . You want your set-ups to be as rigid as possible . Once you get chatter in the middle of shaft , it is darn near impossible to get it out !


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## erikmannie (Feb 15, 2020)

mmcmdl said:


> Every little detail helps in lathe work , especially in shaft work . You want your set-ups to be as rigid as possible . Once you get chatter in the middle of shaft , it is darn near impossible to get it out !



Yes, I have had that happen. A recipe for scrap material.


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## erikmannie (Feb 15, 2020)

I believe that this is the gear configuration on a stock PM-1030V. I am almost positive this is what I have. I wonder what size threads one can cut with this gear configuration.


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## mmcmdl (Feb 15, 2020)

erikmannie said:


> Yes, I have had that happen. A recipe for scrap material.



Yes , so have I .  Had to stretch cylindrical grinders for oversize shafts for years . When your wheel decides to break down at the very most worst spot possible , it was a very delicate process to save the shaft . And , sometimes you couldn't , if close to your finish OD . Part of the trade , you get used to it .


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## ttabbal (Feb 15, 2020)

Threading on a PM1127 lathe - turning instead of threading
					

Does anyone have a Precision Matthews PM1127 lathe and has been threading with it? I put it on threading leadscrew, going from right to left. I've tried on A, B, C, speeds. It turns the workpiece instead of threading. I tried different depths of cut from .001 to .010.  I used a carbide threading...




					www.hobby-machinist.com
				




I know it's for a different model, but the chart looks like it works the same way.


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## erikmannie (Feb 15, 2020)

Generally speaking, I wonder how practical it is to change the gear configuration most of the times that you are going to cut threads. I'm sure that many people are gonna reach for the tap and die.


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## ttabbal (Feb 15, 2020)

I use taps frequently. I like single point external threading though. It helps that I recently built an electronic leadscrew. So I just push a couple buttons and I'm off.


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## middle.road (Feb 15, 2020)

erikmannie said:


> Generally speaking, I wonder how practical it is to change the gear configuration most of the times that you are going to cut threads. I'm sure that many people are gonna reach for the tap and die.


Depends on what quality of thread you need.
With a quick change on the 1440 - no problem, now when I only had the Logan, I'd do as you noted and run a die. Changing the gears is a PITA.


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## erikmannie (Feb 15, 2020)

ttabbal said:


> Threading on a PM1127 lathe - turning instead of threading
> 
> 
> Does anyone have a Precision Matthews PM1127 lathe and has been threading with it? I put it on threading leadscrew, going from right to left. I've tried on A, B, C, speeds. It turns the workpiece instead of threading. I tried different depths of cut from .001 to .010.  I used a carbide threading...
> ...


That thread looks to be entirely pertinent to my issue.


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## erikmannie (Feb 15, 2020)

I will pick this up again tomorrow. Thanks for the help!


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## erikmannie (Feb 15, 2020)

middle.road said:


> Depends on what quality of thread you need.
> With a quick change on the 1440 - no problem, now when I only had the Logan, I'd do as you noted and run a die. Changing the gears is a PITA.


One day I will have a lathe where you don't have to change the gears. In the meantime, I have the feeling that I will be spending a lot of time changing gears!


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## mikey (Feb 15, 2020)

I dunno', change gear lathes aren't so bad. They can definitely cut more threads than most lathes with just a QCGB. You sort of get used to changing gears once you know what you're doing and it doesn't take a whole lot of time and effort. Don't get me wrong; a QCGB is nice to have but it doesn't function any different than any other lathe and it certainly doesn't make you a better machinist.


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## erikmannie (Feb 15, 2020)

mikey said:


> I dunno', change gear lathes aren't so bad. They can definitely cut more threads than most lathes with just a QCGB. You sort of get used to changing gears once you know what you're doing and it doesn't take a whole lot of time and effort. Don't get me wrong; a QCGB is nice to have but it doesn't function any different than any other lathe and it certainly doesn't make you a better machinist.



I am going to learn how to do it. The threads linked above contain most of the answers.

I will make a forum post (with pictures) the first time I slog through it.


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## middle.road (Feb 15, 2020)

Especially after picking up on Will's 'piece o' paper' trick.  Totally forgot that.
Makes me what to re-visit my Logan - then I remember that the half-nuts are chowdered and that is yet another item on the 'To-Do' list.   


mikey said:


> I dunno', change gear lathes aren't so bad. They can definitely cut more threads than most lathes with just a QCGB. You sort of get used to changing gears once you know what you're doing and it doesn't take a whole lot of time and effort. Don't get me wrong; a QCGB is nice to have but it doesn't function any different than any other lathe and it certainly doesn't make you a better machinist.


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## erikmannie (Feb 15, 2020)

I wonder how long it takes a person to switch out the gears, assuming that they know how to do it.


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## mmcmdl (Feb 15, 2020)

erikmannie said:


> I wonder how long it takes a person to switch out the gears, assuming that they know how to do it.



You sound like my boss !


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## mikey (Feb 16, 2020)

erikmannie said:


> I wonder how long it takes a person to switch out the gears, assuming that they know how to do it.



Once you lay out the tools and gears you need, takes only a few minutes. My Emco lathe has a QCGB that is actually quite good but I don't hesitate to change gears if I need to cut something the stock gears cannot handle. Just think of all the guys with "old iron" QCGB lathes that don't have change gears. If they don't have the thread pitch gears they need in their QCGB then they cannot cut that special thread on the lathe. Most of us know that a lathe is not complete without a full set of change gears, even if yours has a QCGB ... surprise!


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## darkzero (Feb 16, 2020)

erikmannie said:


> One day I will have a lathe where you don't have to change the gears. In the meantime, I have the feeling that I will be spending a lot of time changing gears!



Most lathes will need some sort of gear change, from imperial to metric at the least. That is unless you go CNC or get a big and/or expensive industrial lathe. Prepare to spend a lot of money on a lathe that doesn't require swapping a gear.


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## mmcmdl (Feb 16, 2020)

darkzero said:


> Most lathes will need some sort of gear change, from imperial to metric at the least. That is unless you go CNC or get a big and/or expensive industrial lathe. Prepare to spend a lot of money on a lathe that doesn't require swapping a gear.



I got spoiled at a young age . I had this lathe at my disposal for 15 years . If I could find one in good working order , I'd buy it in a heartbeat . 






						LeBlond Makino Count 15 / NEF CT 40 CNC Lathe T30296: Amazon.com: Tools & Home Improvement
					

LeBlond Makino Count 15 / NEF CT 40 CNC Lathe T30296: Amazon.com: Tools & Home Improvement



					www.amazon.com


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## erikmannie (Feb 16, 2020)

mrpete222 shows a whole lot of this work in his Shop Tips #220, #221, #222, #224 and #225. It doesn’t look like any kind of a problem.


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## erikmannie (Feb 16, 2020)

I am going to try this today. I will post pictures in this thread. I will be careful so as not to disable the machine.


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## francist (Feb 16, 2020)

I don't know how you're intending to cut your threads (using the compound or the cross-feed) but if you're going to use the compound I suggest you revisit the angle you have it set to first. As of your last photos, it's set way to shallow and will cut lopsided threads. The angle it needs to follow is what I've lined in green -- 30 degrees off perpendicular to the work. Your photo shows it at 60 degrees from perpendicular.

If you're using the cross-feed method of taking your cut it won't matter -- thread away!


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## erikmannie (Feb 16, 2020)

francist said:


> I don't know how you're intending to cut your threads (using the compound or the cross-feed) but if you're going to use the compound I suggest you revisit the angle you have it set to first. As of your last photos, it's set way to shallow and will cut lopsided threads. The angle it needs to follow is what I've lined in green -- 30 degrees off perpendicular to the work. Your photo shows it at 60 degrees from perpendicular.
> 
> If you're using the cross-feed method of taking your cut it won't matter -- thread away!
> 
> View attachment 313803



Looks like I got the angle wrong. I’m just starting on this now. I will post a picture of the change that I made.


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## erikmannie (Feb 16, 2020)

I found this picture on the internet. It looks like he has the angle set correctly. Nice use of a combination square.


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## francist (Feb 16, 2020)

It's an extremely common error -- where the graduations start is not consistent from one manufacturer to another so lots of guys get confused at the beginning. Once you develop an eye for what looks right, you'll see it immediately when it's not. 

-f


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## erikmannie (Feb 16, 2020)

francist said:


> It's an extremely common error -- where the graduations start is not consistent from one manufacturer to another so lots of guys get confused at the beginning. Once you develop an eye for what looks right, you'll see it immediately when it's not.
> 
> -f


In the photo above where he has the angle set correctly, the value of the compound angle on the scale would be hard to read, as it is mostly covered. I like the use of a combination square.


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## middle.road (Feb 16, 2020)

Joe Pie does it straight on.


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## francist (Feb 16, 2020)

erikmannie said:


> In the photo above where he has the angle set correctly, the value of the compound angle on the scale would be hard to read, as it is mostly covered



I see, that could be part of the problem with people trying to set it then! Why manufacturers do that is beyond me.

I have an older machine and the scale is very visible. but I still rely on counting off the degree marks from perpendicular just to make sure. It's fast and easy, and I know that it's correct for my machine.


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## erikmannie (Feb 16, 2020)

So right when I was about to change the gears to cut 20 TPI, my Dad stopped by so I had a helper. This was a super easy task. I will post pictures and cite the very few challenges that I faced.

Here is the gear setup that came with the lathe: set up for turning, facing, boring, etc. (slow carriage and cross slide power feed speeds).


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## erikmannie (Feb 16, 2020)

I looked at the chart on the lathe (_*not*_ the manual, just be to sure) to find out what gears I needed; I made sure that I had all these gears (I did) before proceeding. I loosened the *two* M6 bolts that secure the quadrant (or banjo) in place, and took off the old gears. I used an 8mm open end wrench and an M5 hex key to remove the "old" gears. I made note of the position of the washers, bolts and T nuts.

Here is the banjo ready for a new configuration of change gears:


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## erikmannie (Feb 16, 2020)

Around this point, I realized that this is a really easy task and that I should never fret about having to do it. Here is a picture of the "stock" (turning) change gears after I pulled them off. You will see bolts, washers, and bushings that hold two gears together. PM supplies an extra spacer (that I needed today) and an extra bushing (used to attach two gears together ("compound gears", says Mr. Pete). Both the bushings and washers are symmetric, so you can't put them on backwards.


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## erikmannie (Feb 16, 2020)

I failed to take a picture of the *spacer, referred to as "H" on the threading configuration chart*. It is a black oxide, keyed metal spacer.

Here are the first two pairs of gears installed on the banjo. I lubed the ball oiler and gear teeth with way oil. I used a sheet of Post-It paper to set gear lash.


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## erikmannie (Feb 16, 2020)

Some of these bushings were a bit of a tight fit. You have to make sure that you put the gear straight on and indexed perfectly with the key slot, obviously. I used way oil to help coax it in. I had to tap in one gear set. I may well need a gear puller to get them off, which doesn't bother me.

I wanted to file some of the parts a thou or so, but my Dad advised against it.

I did have to punch out one or two bushings. I laid the change gear *on top of* a bench vise and used a socket to punch out the bushing.

The gear and bushing below needed to be hammered together. I am sure that I will have to punch out the bushing when I take it apart.


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## erikmannie (Feb 16, 2020)

Here is a picture of all the change gears needed to cut 20 TPI installed on the banjo.


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## erikmannie (Feb 16, 2020)

The change gear install is complete. The banjo is back in place with proper lash set and way oil applied to the gear teeth.


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## erikmannie (Feb 16, 2020)

Here is the 20 TPI cut. Now I will set about cutting a lot of 20 tpi internal and threads, just for practice and fun.


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## erikmannie (Feb 16, 2020)

Here is a picture of the spacer ("H") slipped onto a keyed bushing in order to attach it to a change gear:


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## erikmannie (Feb 16, 2020)

So here are some self explanatory pictures of external single point threading:


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## erikmannie (Feb 17, 2020)

So I made a male 1/4-20 thread as seen below. The fit seems to be perfect because it started out tight and the Grade 8 nut served as a die.

I am having an issue with the lathe turning a taper. I have suspected this since the first day I got it. It has nothing to do with the tailstock. I might need to adjust the position of the spindle.

If I chuck up even the most rigid round stock and turn it as carefully as possible, I will get a taper of about .0007" per inch.

For this bolt, I attempted to turn a major diameter of .2500", I turned .2500" at the far end, and the workpiece was .2514" at the chuck end. Same story for the .2175" pitch diameter. This was the first time that I used my Shars screw pitch micrometer, so I was happy to be anywhere the ballpark there. I have a bad time with Shars mikes. I bought Starrett outside mikes, but not one for threads.

So I will cut a 9/16-20 male thread tomorrow with an eye on this taper situation. I will start by turning some large round stock to get some exact measurements for the extent of the taper.


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## mikey (Feb 17, 2020)

Erik, there are three key reasons for the lathe cutting a taper. First, the headstock may not be aligned with the ways. Second, the lathe may not be level. Third, the tailstock may not be aligned with the spindle. Lots of info on the net about each of these issues. Also do not overlook the possibility of tool deflection causing inaccuracies

I wanted to point out that your threading tool has a very positive rake. That typically produces gnarly cuts in brass and will often produce torn or jagged edges on your threads. It also tends to dig in on many other materials when trying to thread on the lathe. It is better to use a threading tool with zero rake, especially for brass. If you grind it with 15 degree relief angles on each side you will cut much cleaner threads.

It also appears that the carbide tool you're using is not cutting well. Not sure if this is due to too low a turning speed or a bad/junk insert of what but brass should cut with a near mirror finish. Something is very off with your tool.


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## ttabbal (Feb 17, 2020)

One thing with the gear change. Don't hammer them. I did that initially and broke one of the bushings. PM sent me a couple of spares. I used files to get things fitting better. It doesn't take much, and make sure not to go too far. You don't want slop. Glad you got the charts figured out. They are weird at first, but you get the hang of it.


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## erikmannie (Feb 17, 2020)

mikey said:


> Erik, there are three key reasons for the lathe cutting a taper. First, the headstock may not be aligned with the ways. Second, the lathe may not be level. Third, the tailstock may not be aligned with the spindle. Lots of info on the net about each of these issues. Also do not overlook the possibility of tool deflection causing inaccuracies
> 
> I wanted to point out that your threading tool has a very positive rake. That typically produces gnarly cuts in brass and will often produce torn or jagged edges on your threads. It also tends to dig in on many other materials when trying to thread on the lathe. It is better to use a threading tool with zero rake, especially for brass. If you grind it with 15 degree relief angles on each side you will cut much cleaner threads.
> 
> It also appears that the carbide tool you're using is not cutting well. Not sure if this is due to too low a turning speed or a bad/junk insert of what but brass should cut with a near mirror finish. Something is very off with your tool.



My lathe is not yet level. It is tilted a little down on the “front side, tailstock end” corner. I can tell because this is where the excess way oil pools in the clean chip tray after a clean and lube. Thanks for the troubleshooting help; I will also read about aligning the headstock with the ways.

I didn’t use any carbide in this thread. I did use Made in China HSS inserts.

The threading tool is a preground “combination chamfer & threading tool bit”. I will only use it for chamfering from now on.

Tomorrow when I cut the 9/16-20 I will use some carbide or HSS inserts made just for threading. The stock will be mild steel.


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## erikmannie (Feb 17, 2020)

ttabbal said:


> One thing with the gear change. Don't hammer them. I did that initially and broke one of the bushings. PM sent me a couple of spares. I used files to get things fitting better. It doesn't take much, and make sure not to go too far. You don't want slop. Glad you got the charts figured out. They are weird at first, but you get the hang of it.



I wanted to file them, and do so patiently and incrementally. It was my Dad’s idea to forego filing and hammer them. I’m surprised that I didn’t break a bushing because it required a lot of force.


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## Aukai (Feb 17, 2020)

I have no idea if this is pertinent or not, but does running the machine in high range, vs low range make a difference? you seem to be in high range I think.


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## erikmannie (Feb 17, 2020)

Aukai said:


> I have no idea if this is pertinent or not, but does running the machine in high range, vs low range make a difference? you seem to be in high range I think.



I do have it in high range because I like carbide inserts for turning, facing and boring.

As you know, the range (high or low) or spindle speed (RPM) has no effect on the thread pitch that is cut. For my reaction time, I can’t do threading with an RPM much higher than 270. I usually choose about 170 RPM which allows me to properly engage the threading dial.


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## mikey (Feb 17, 2020)

erikmannie said:


> My lathe is not yet level. It is tilted a little down on the “front side, tailstock end” corner. I can tell because this is where the excess way oil pools in the clean chip tray after a clean and lube. Thanks for the troubleshooting help; I will also read about aligning the headstock with the ways.
> 
> I didn’t use any carbide in this thread. I did use Made in China HSS inserts.
> 
> ...



Those Chinese inserts seem to suck! You would be far better off grinding and using HSS tools, Erik. This goes for both turning and threading tools.


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## Aukai (Feb 17, 2020)

LOL I'm not sure what I know, that's why I mentioned it to see.


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## erikmannie (Feb 17, 2020)

mikey said:


> Those Chinese inserts seem to suck! You would be far better off grinding and using HSS tools, Erik. This goes for both turning and threading tools.



I have had good luck with the inserts that I received from PM. The carbide inserts used for boring on mild steel remove a lot of material quickly, and you can use a faster RPM so the work goes faster. I have never tried premium inserts.

I just started grinding HSS tool bits. I bought ten preground ones so that I could get a look at the angles. Many have already required sharpening. The ones that I bought were very handsome:


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## stupoty (Feb 17, 2020)

erikmannie said:


> Looks like I got the angle wrong. I’m just starting on this now. I will post a picture of the change that I made.



you might have got the "wrong 30" some lathes have zero as parallel with bed and some have zero as perpendicular.


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## starr256 (Feb 17, 2020)

I have a PM1030V. Once you get the bushings sorted out (from the factory they need a little filing to smooth fit), I find that it takes about 5 minutes to switch gears. It took me a bit, but I found the manual had the best diagrams for gear changes, so I keep it handy. Other than realizing I really need the thread wires to know when I am done and that threading right to left works better for me than left to right in reverse on the backside, I have not had a problem. note, I am a rank novice of very limited experience.


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## erikmannie (Feb 17, 2020)

So after owning my lathe for 7 weeks, I finally put a level on the bed (in many places, obtaining the same reading on the level). The machine is tilted down toward the tailstock side. I do not own a machinist's level yet.

A level placed on the cross slide shows it to be level front to back. It would appear that I need to shim under the tailstock side.

The picture showing not level is the reading that I get anywhere on the bed. The picture showing level is the cross slide.


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## erikmannie (Feb 17, 2020)

starr256 said:


> I have a PM1030V. Once you get the bushings sorted out (from the factory they need a little filing to smooth fit), I find that it takes about 5 minutes to switch gears. It took me a bit, but I found the manual had the best diagrams for gear changes, so I keep it handy. Other than realizing I really need the thread wires to know when I am done and that threading right to left works better for me than left to right in reverse on the backside, I have not had a problem. note, I am a rank novice of very limited experience.



I am glad you told me that. I would have filed the _gears_.

I just bought Brown & Sharpe thread measuring wires because my Shars screw thread mike's ratcheting mechanism is *very* inconsistent, this right out of the box. I have consistency problems with all 12 of my Shars mikes. I don't have any problems with any of my 7 Starrett new & used mikes.


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## erikmannie (Feb 17, 2020)

stupoty said:


> you might have got the "wrong 30" some lathes have zero as parallel with bed and some have zero as perpendicular.


You are spot on. When I have it set up correctly for threading, the angle reading on the compound reads 60.


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## T Bredehoft (Feb 17, 2020)

I'm 38 minutes late with this. Sorry.

Erik, I don't see a reference to it, but the threads shown above with the nut screwed on are WRONG. Your compound is set at 59º, not 29º. The degree quatrant may read 29, but the threads have the wrong profile.


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## stupoty (Feb 17, 2020)

erikmannie said:


> You are spot on. When I have it set up correctly for threading, the angle reading on the compound reads 60.



It's a common thing , the best time to find you have done it is after fiddling about for ages trying to do a thread on a small part with little room especially if using a tailstock centre to suport it and then having to set it all up again 

Stu


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## ttabbal (Feb 17, 2020)

Regarding leveling.. It's not about what you see on a spirit level. It's about the twist in the bed. It doesn't have to be level to the world at all. Though it's a good idea for oil reservoirs and such. And to not have round stuff roll away.  

Look up the two collar test. Do that and by adjusting the height of a couple of the mounts you should be able to dial it in. Then check tailstock alignment. I doubt a new lathe from PM has the headstock misaligned. It's possible, but I would check the mounting first.


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## erikmannie (Feb 17, 2020)

T Bredehoft said:


> I'm 38 minutes late with this. Sorry.
> 
> Erik, I don't see a reference to it, but the threads shown above with the nut screwed on are WRONG. Your compound is set at 59º, not 29º. The degree quatrant may read 29, but the threads have the wrong profile.


I will look at that now because I am just about to cut 9/16-20 male threads. I am aiming for 30 degrees.


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## erikmannie (Feb 17, 2020)

I failed to successfully cut threads today. I chose to cut 1/2-20 because the hardware store did not have 9/16-20. I failed because I engaged the half nut lever a little too late (when I was nearly done, unfortunately). I tried to salvage the work, but to no avail.

My chosen RPM was 263, and obviously I couldn't keep up with that. From now on, I will choose a lower RPM.

I took _a lot of picture_s of this basic operation.

Here is a brand new 60 degree carbide insert:


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## erikmannie (Feb 17, 2020)

Here is the insert centered with the MT2 slim-line live center:


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## erikmannie (Feb 17, 2020)

Here is my groove and clearance. I plunged .060". The groove was just barely wide enough for my reflexes and the location of the chuck jaws.


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## Aukai (Feb 17, 2020)

Yikes is right....


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## erikmannie (Feb 17, 2020)

Here is my whole setup with the tool near the headstock:


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## erikmannie (Feb 17, 2020)

Here is the setup with the tool at the tailstock end:


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## erikmannie (Feb 17, 2020)

Here is the mistake. I can't hit the threading dial accurately every time with this higher RPM.


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## erikmannie (Feb 17, 2020)

Fishtail check:


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## erikmannie (Feb 17, 2020)

Here is the carbide cutting about .003"-.005" with no cutting fluid. Worked smoothly for light cuts.


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## erikmannie (Feb 17, 2020)

Here is the Shars screw thread micrometer measuring the bolt that I bought at the hardware store. The forum software rotated the picture. I had definitely looked up the major and min/max pitch diameters and written them down. This is just a sanity check (which I compared to what I was cutting in the lathe):


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## erikmannie (Feb 17, 2020)

Here is the double (spoiled) thread that I tried to salvage. I turned it down to .2500" and I will make a 1/4-20 out of it:


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## darkzero (Feb 17, 2020)

Erik, what you are using there is not a threading tool, it's a turning tool. That insert is a CCMT that is a diamond shape which has an 80° included angle for the tip. Look at your fishtail pic, you can clearly see the gaps.

A triangle shape like TCMT has 60° included angle tips but they are still turning tools & the nose radius is tool large for threading. You can get away with a triangle insert for threading only if for a large diameter very coarse pitch thread.


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## erikmannie (Feb 17, 2020)

darkzero said:


> Erik, what you are using there is not a threading tool, it's a turning tool. That insert is a CCMT that is a diamond shape which has an 80° included angle for the tip. Look at your fishtail pic too, you can cleay see the gaps.
> 
> A triangle shape like TCMT has 60° included angle tips but they are still turning tools & the nose radius is tool large for threading. You can get away with a triangle insert only if you are threading a large diameter coarse pitch thread.


I see. Is that an insert for both right and left hand turning? Or for chamfering, perhaps?

I have a threading kit that I ordered with the lathe. The inserts look a lot like equilateral triangles (60 degrees, now I am getting it!).

I am glad that I posted the pictures so that someone could point out this rookie mistake.


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## darkzero (Feb 17, 2020)

erikmannie said:


> I see. I have a threading kit that I ordered with the lathe. The inserts look a lot like equilateral triangles.



Triangle shape insert threading tools are usually found in these 2 types, the first being more common.

Lay down type













On edge/stand up type









Other than the tool you are using, keep doing what you are doing & you should produce some nice threads.


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## darkzero (Feb 17, 2020)

erikmannie said:


> Is that an insert for both right and left hand turning? Or for chamfering, perhaps?



A CCMT insert can be used for both RH & LH turning. That tool orientation you have can be used for turning both directions but generally not for heavy roughing. That tool orientation is more commonly used for chamfering but it's not a perfect 45° chamfer. It would give you a 40° chamfer but close enough & in most cases doesn't matter.

I use SCMT for chamfering which is a square shape insert for 45° chamfers. But that tool you have is convenient cause it saves on having to buy a different style insert & use inserts you ready have (assuming you have other tools that use CCMT).


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## stupoty (Feb 18, 2020)

erikmannie said:


> My chosen RPM was 263, and obviously I couldn't keep up with that. From now on, I will choose a lower RPM.



A lower rpm is much easier to work with , there is no shame in threading under 100 rpm 

Stu


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## shooter123456 (Feb 18, 2020)

Also, it looks like you are using the high speed range.  I would switch it to the low speed range instead.  It is rare that anything needs to be done over 1000 RPM and you will have more torque throughout.  That is especially helpful when threading because you can slow it down further and maintain the torque needed to cut.


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## erikmannie (Feb 18, 2020)

shooter123456 said:


> Also, it looks like you are using the high speed range.  I would switch it to the low speed range instead.  It is rare that anything needs to be done over 1000 RPM and you will have more torque throughout.  That is especially helpful when threading because you can slow it down further and maintain the torque needed to cut.


I agree. It was hard to dial in a choice between 109 and 158 RPM. I would have wanted somewhere in between for threading.

I will be changing it back to low range. The lathe is so scary at the higher RPMs!


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## erikmannie (Feb 18, 2020)

So I was successful today. I won't be overdoing it on the photos after today, but I did get some good action shots. I am soliciting criticism (e.g. my parting blade is not sharpened correctly, my lathe is filthy).


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## erikmannie (Feb 18, 2020)

So here's how it went. I looked up to find out that the major diameter of a 1/4-20 thread was .2500". This is mild steel turned to .2500". It looks like the forum is going to rotate some of the photos.


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## erikmannie (Feb 18, 2020)

I bought a 1/2" threading kit from Precision Matthews when I bought the lathe. I had to use HSS today. In this kit, the carbide inserts only fit in the internal threading tool, and the HSS only fit in the tool shown below:


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## erikmannie (Feb 18, 2020)

Here is the insert centered to the live center.


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## erikmannie (Feb 18, 2020)

This insert will not allow me to thread all the way to the end with this live center.


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## erikmannie (Feb 18, 2020)

Here is my parting blade set to the right height. I am making .040" grooves in the workpiece.


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## erikmannie (Feb 18, 2020)

A groove just wide enough to do the job.


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## erikmannie (Feb 18, 2020)

This is the first time that I have ever used a fishtail with an insert tool:


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## erikmannie (Feb 18, 2020)

After cutting a groove in the headstock end, this is my setup for that end:


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## erikmannie (Feb 18, 2020)

This was the right RPM choice for threading, I'll tell ya. Easy money.


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## erikmannie (Feb 18, 2020)

Touch off and set zero on the cross slide (I have a DRO).


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## erikmannie (Feb 18, 2020)

After 2 or 3 passes:.


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## erikmannie (Feb 18, 2020)

I use a lot of dark thread cutting oil ($20/gallon on Amazon!).


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## erikmannie (Feb 18, 2020)

Ready to start measuring the pitch diameter. I got so lucky. It was right there.


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## erikmannie (Feb 18, 2020)

Part off the end. It was still in the tailstock live center, obviously.


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## erikmannie (Feb 18, 2020)

This needs to be faced and chamfered:


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## erikmannie (Feb 18, 2020)

Part off the work:


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## erikmannie (Feb 18, 2020)

Chuck it up to face and chamfer. I got this idea from a Mr. Pete video:


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## erikmannie (Feb 18, 2020)

Setting the chamfer tool to 45 degrees:


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## erikmannie (Feb 18, 2020)

Most of my chamfer was faced off.


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## Liljoebrshooter (Feb 18, 2020)

What is that insert in your threading tool?  It doesn't look like it has a sharp point and it has numbers. 
Joe


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## Liljoebrshooter (Feb 18, 2020)

And it also has a lot of negative rake.  A positive rake tool will cut better on smaller machines.
Joe


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## erikmannie (Feb 18, 2020)

Liljoebrshooter said:


> What is that insert in your threading tool?  It doesn't look like it has a sharp point and it has numbers.
> Joe



It was on the list of options to be purchased with the lathe. The box says “1/2” Threading Kit”. I don’t know what the 1,2 and 3 signify. At machining school, we used 60 degree HSS tool bits.


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## shooter123456 (Feb 18, 2020)

erikmannie said:


> It was on the list of options to be purchased with the lathe. The box says “1/2” Threading Kit”. I don’t know what the 1,2 and 3 signify. At machining school, we used 60 degree HSS tool bits.


I might be wrong, but I don't think that is the insert.  It looks like you are cutting using the insert seat.  

If you have a look at this picture, you can see the silver seat underneath the yellow cutting insert.  Your picture showing the insert on center looks like it is very low.  The kit you purchased should have 2 external cutting inserts with it.


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## erikmannie (Feb 18, 2020)

shooter123456 said:


> I might be wrong, but I don't think that is the insert.  It looks like you are cutting using the insert seat.
> 
> If you have a look at this picture, you can see the silver seat underneath the yellow cutting insert.  Your picture showing the insert on center looks like it is very low.  The kit you purchased should have 2 external cutting inserts with it.


I believe that you are correct. I wondered why the 60 degree protrusion didn't extend out very far.

I am so glad that I posted the pictures. I would have spent 40 years cutting with the insert seat!

I am surprised that I could get it so wrong, and even more surprised that I ended up with a serviceable bolt.

I will try it again tomorrow! I _was_ going to try knurling for the first time ever.


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## shooter123456 (Feb 18, 2020)

erikmannie said:


> I believe that you are correct. I am so glad that I posted the pictures. I could have spent 40 years cutting with the insert seat!


It looks like it worked just fine and your threads look a lot better than some of the ones I have done using the correct insert... Who knows, maybe the seat is even better and no one knew.


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## erikmannie (Feb 18, 2020)

shooter123456 said:


> It looks like it worked just fine and your threads look a lot better than some of the ones I have done using the correct insert... Who knows, maybe the seat is even better and no one knew.



When you use that much cutting oil, I imagine that any 60 degree angle would cut smoothly.


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## Nigel123 (Feb 18, 2020)

Glad it worked out for you
As you cut more threads it becomes easier less stress
I maybe wrong but I was taught never part off a piece with it supported by the center
Maybe because it is a long piece and will give before it binds it was okay


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## erikmannie (Feb 23, 2020)

So I have made a cut more threads. I did not take pictures, but I have some points:

(1) I noticed that you can (if needed) turn off power and rotate the chuck by hand. This either backward or forward. This came up for me because I was taking more aggressive cuts (.003") and the insert dug into the work (whereupon I hit the e-stop). If this happened near the end of the pass, I would finish the pass by hand.

(2) I gather that one needs to leave the split nut engaged throughout the entire process for cutting a *metric* thread. Although I was cutting an Imperial pitch, I previewed this technique. Long story short, I wish that I had made a wider groove near the chuck. With the PM-1030V, *you have to power off before switching from forward to reverse*. Also, with the PM-1030V you need to start at low RPM (e.g. 50). That being the case, I would want a groove of at least 3/8" wide, primarily for the trip back (i.e. spindle in reverse). Starting at 50 RPM, I needed time to turn up the RPM in order to get enough torque to be able to get back to the starting point, as this is essentially a spring pass with a cutting tool with a negative rake.

(3) Speaking of torque, I was cutting a 1'-8 (1" diameter, 8 TPI) thread in mild steel and the machine could really only handle a .002" DOC. Yes, I had a sharp carbide 60 degree insert and plenty of cutting fluid. That made for a lot of passes.

(4) I found that nailing the major diameter made for a better finished result. I was happy to see that there is a range. Even if you have a taper, you can get all ODs in that range.

(5) I found that having a hardware store bolt of the desired size makes for a good screw thread mike comparison before measuring my work on the machine, or a thread measuring wires comparison for that matter. I found myself using the measured value from the hardware store bolt way more often than the pitch diameter listed in the reference tables.

(6) I found that you can fine tune (with the pitch diameter, of course) how tightly you want the nut to thread on and off. Is this a stud for somebody who wants to thread it on by hand or are you after a tighter fit, for example?

(7) The deep thread in the 1"-8 required me to use the bench grinder to grind a relief in the steel insert seat because the 30 degree insert was not long enough to do the job. One could use a HSS tool bit to avoid this issue.


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## erikmannie (Feb 23, 2020)

On the 1"-8, I had to hit the e-stop about a dozen times. You have to think that is due to overly aggressive cuts.

When the cutting tool dug into the work, the spindle (rotating at between 106 and 180 RPM) would be unable to keep going. I would hit the e-stop button ASAP. I ended up increasing the RPM in an effort to get more torque. One wonders how much more torque is gained from going from 158 to 180 RPM. This is a 1 HP brushless DC motor in low range.

Is it a strategy to engage the thread dial at, say, 180 RPM and then turn up the RPM for the middle of the pass, and then turn the RPM back down for a more controlled stop near the chuck?

One time I did run in too far and the insert holder made contact with a chuck jaw, stopping the rotation of the chuck. E-stop ASAP!
My lathe always starts right back up after this, but I would expect to blow a fuse at some point, overloading the motor like this.


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## erikmannie (Feb 23, 2020)

I had a small amount of 12L14 for one stud, and that machines so easily I felt like I was cheating! I would be inclined to buy some 12L14 hex (which costs about 20% more than mild steel), but I won't roll out the red carpet for myself for practice pieces. I will practice on mild steel and then, if I ever want it to be easy, use 12L14.


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## erikmannie (Feb 23, 2020)

I will also just quickly reiterate that changing the change gears is a snap.

Here are some pics. The 1/2-20 is 12L14. The 1/4-20 and 1"-8 are mild steel. The 1" has chatter because the lass pass was a roughing pass with multiple unlubricated spring passes to clean it up for a pitch diameter measurement. When I measured it, I was there.


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## erikmannie (Feb 23, 2020)

Finally, as much as I dislike all things Shars, I will concede that my Shars 0-1" screw thread mike does the job.


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## Aukai (Feb 23, 2020)

Your giving me incentive to give it a try, I'm a bit leery of it. 
I bought a thread wire set, and when it came out of the package it was a bunch of Pixel sticks, that came out of the pouch.


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## erikmannie (Feb 23, 2020)

Aukai said:


> Your giving me incentive to give it a try, I'm a bit leery of it.
> I bought a thread wire set, and when it came out of the package it was a bunch of Pixel sticks, that came out of the pouch.



So your thread wires were broken? I bought a pair of Brown & Sharpe on Amazon for about $33, and they are great.

You simply must try single point threading. It is one of the most fun things that I have ever done.

This morning I had two failures. The first one I overshot the pitch diameter, and then when I tried again with new stock, I overshot the major diameter on that.

When I overshot the pitch diameter, I didn’t realize that dialing in a thou on the compound would result in greater than .001” reduction in diameter. This is because I have a diameter machine. Well, now I know.

Another problem that I had this morning is that I took an overly aggressive cut (.003”) and it ruined the workpiece. The insert dug in, I hit the e-stop; I tried to finish the cut by hand and instead of cutting like I wanted, it just tore off the thread. I don’t know why the insert didn’t follow the helix; probably because it was an overly aggressive DOC!


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## jwmelvin (Feb 23, 2020)

I’m confused about 0.003” being an aggressive cut. I haven’t cut threads but my small lathe (G0602 10x22) certainly takes plenty larger cuts turning. Are you advancing the cross slide or the compound? I must be missing something?


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## stupoty (Feb 23, 2020)

jwmelvin said:


> I’m confused about 0.003” being an aggressive cut. I haven’t cut threads but my small lathe (G0602 10x22) certainly takes plenty larger cuts turning. Are you advancing the cross slide or the compound? I must be missing something?



I think its todo with the engagement of the tool as it's a form tool the area is quite large, i mostly do a 0.010 or less first pass and back it down at the depth increases, 0.003 per pass sounds not to bad. (I do my threading on a 13 inch lathe btw)

Stu


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## Nigel123 (Feb 23, 2020)

I take the first cut .010 to .015 then decrease to .005 over the next 4 cuts
I set the compound to 29.5 degrees and divide the no of threads per inch into .75
that gives me a close measurement on the amount of infeed for the compound
I only use hss bits sharpened with no rake
Have some carbide inserts but as you mentioned depth is a problem also machining with a center
Always use the half nuts when possible (sae) lot quicker and less nerve racking


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## erikmannie (Feb 23, 2020)

jwmelvin said:


> I’m confused about 0.003” being an aggressive cut. I haven’t cut threads but my small lathe (G0602 10x22) certainly takes plenty larger cuts turning. Are you advancing the cross slide or the compound? I must be missing something?


I was surprised, too. When I am nearer to the outside of the work, or working on something much smaller than 1" OD, I can easily make a .010" cut; I have a diameter machine, so a .010" cut reduces the OD by .020".

The .003" figure was single point threading on a 1", 8 TPI mild steel stud so a lot of material is coming out even with a .003" DOC when you are near the end of the task. I am advancing on the compound at 30 degrees.

My RPM was about 206, and note that at 8 TPI the carriage is moving pretty quickly.

Summary: dialing in .003" on the compound set at 30 degrees near the end of an 8 TPI thread on a well lubricated 1" mild steel bolt at 206 RPM will bury the carbide insert into the workpiece.

I just finished one of these with zero issues, and my cuts near the end of the task were only .001" on the compound.


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## erikmannie (Feb 23, 2020)

Let's see if I can do a simple trigonometry problem without making a mistake:

I want to detemine how much I need to dial in a compound set at 30 degrees in order to reduce the diameter by .001". I ask this because we know how far we want to go straight in by looking at the difference between the major diameter and the minor diameter listed in a reference table for a given thread pitch.

We have a 30 degree angle where the compound comes in to cut. The compound travel is then the hypotenuse of a triangle where the cross slide travel is the adjacent side.

So the angle is 30 degrees.  The length of the hypotenuse is, say, 1 (this is moving in the compound one unit). Cosine is the adjacent divided by the hypotenuse.

The cos(30)= .866, so the ratio of the adjacent side to the hypotenuse is .866.

If I did this right, dialing in .001" of the compound reduces the minor diameter by 86.6% of that, or .00086". _But that is not what was asked._

Note that 1 divided by .866 is 1.155 ("the inverse of .866 is 1.155").

If I did this right, you need to dial in the compound 1.155 thou in order to reduce the diameter by 1 thou.

So in practice, if we still need to go in another .0100", we will need to dial in another .01155" on the compound.

Beating a dead horse here, if the entire task requires going in .1000", we will dial in the compound .1155".


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## Downunder Bob (Feb 24, 2020)

Yes, a QCGB is a wonderful thing to have on any lathe, but is certainly not essential, and even on lathes equipped with a QCGB, it is sometimes necessary to use change gears, mostly when changing from imperial threads to metric, but also there are many threads that are outside the range of most QCGB. 

The most common QCGB are set up to cut only the more common threads, but this range can be added to by using change gears.


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## Aukai (Feb 24, 2020)

My thread wires came out like the game pick up sticks, I remember it by the other name....


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## shooter123456 (Feb 24, 2020)

erikmannie said:


> in order to reduce the radius by .001"





erikmannie said:


> in order to reduce the diameter by 1 thou


Maybe a little bit of the confusion comes from this?  If you want to reduce your diameter, you dial in half of what you aim for in reduction.  If you are reducing the radius, your math looks correct to me.


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## erikmannie (Feb 24, 2020)

Aukai said:


> My thread wires came out like the game pick up sticks, I remember it by the other name....
> 
> View attachment 314589



How annoying! Did you return them or fix the problem?


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## erikmannie (Feb 24, 2020)

shooter123456 said:


> Maybe a little bit of the confusion comes from this?  If you want to reduce your diameter, you dial in half of what you aim for in reduction.  If you are reducing the radius, your math looks correct to me.



I fixed it.

 I find it odd that my error was in the wording of the question. Thanks for finding the error and pointing it out.


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## T Bredehoft (Feb 24, 2020)

Depth of cut....interesting. I've been chasing threads (cauaght a few) since 1971, never was concerned about how far to move the compound, (take a little at a time), but when the nut goes on, it's done.


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## erikmannie (Feb 24, 2020)

T Bredehoft said:


> Depth of cut....interesting. I've been chasing threads (cauaght a few) since 1971, never was concerned about how far to move the compound, (take a little at a time), but when the nut goes on, it's done.



Any tips on how to avoid overshooting the cut?


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## T Bredehoft (Feb 24, 2020)

Slowly, slowly catachee monkey.   Keep checking til it fits.


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## Nigel123 (Feb 24, 2020)

Also forgot to mention take some cuts not advancing the compound(read it somewhere)
It is surprising how much it cuts without advancing the cutter
Most times I check with a nut using caution near the finish to get a fit
If I cannot try the thread I use the .75 or .742 divided by the no of threads
I hit it right about 80 percent of time


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## T Bredehoft (Feb 24, 2020)

On production work, I single point about 80% of the thread then run a die on. Comes out right every time.


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## erikmannie (Feb 24, 2020)

T Bredehoft said:


> On production work, I single point about 80% of the thread then run a die on. Comes out right every time.



I have never heard that. It sounds like a fantastic tip.


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## erikmannie (Feb 24, 2020)

Nigel123 said:


> Also forgot to mention take some cuts not advancing the compound(read it somewhere)
> It is surprising how much it cuts without advancing the cutter
> Most times I check with a nut using caution near the finish to get a fit
> If I cannot try the thread I use the .75 or .742 divided by the no of threads
> I hit it right about 80 percent of time



I’m afraid that I need a specific example of the .75 idea. If I am cutting 8 TPI threads, .742 divided by 8 is .09275. Is .09275 the distance to go in? For a 1”-8, my major diameter was 1.000”. So I go in radially .09275” and arrive at .90725”. If so, does .90725 represent the value for the estimated pitch diameter?


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## erikmannie (Feb 24, 2020)

So now I am cutting 1”-8 internal threads. I had to stop to look up the specs for a class B (or should I say Type B?) thread.

So far I have a .750” bore as seen below:


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## erikmannie (Feb 24, 2020)

It looks like the desired dimensions for an internal thread are just taken off a reference chart. The reference chart that I have been using lists 2A and 2B.

Hopefully I should use the 2B figures because that is how I am proceeding.


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## erikmannie (Feb 24, 2020)

Looks like I bore to between .8650“ and 8797”.


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## Nigel123 (Feb 24, 2020)

The 0.75 divided by the number of threads is the formula for the amount for the infeed of the compound set at 30 degrees
8 tpi would be 0.09375
The 0.742 divided by the number of threads is the formula for the compound set at 29.5 degrees
I just go by the drill size for that particular thread seems to work
I always feed with the compound never the cross feed
A little less than 30 degrees lets the cutting tool to only contact on the front edge
Feed in the direction of travel
I never have got into minor or major diameters but will monitor your progress
I am not too old to learn


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## Downunder Bob (Feb 24, 2020)

If you want to make high quality single point threads, Joe Pisinski has an excellent YT Video on how to it properly


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## erikmannie (Feb 25, 2020)

I almost have the bushings ready for the internal threading practice. I had to have everything perfect for the small lathe to part this 2” mild steel.

I tried to upload a picture using my phone, but the file is too large.


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## erikmannie (Feb 27, 2020)

Here is a picture of the 3 bushings that I will use to make 3 nuts:


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## erikmannie (Feb 27, 2020)

I made one nut today, and I want to tell everybody the 2 mistakes that I made: 

(1) I should have done the precision boring and internal threading in a single chucking, and
(2) I should have made the groove before this chucking, _*and*_ approached the groove from the groove side. I part off this grooved area, so it does not need to be concentric with anything. It only needs to have enough room to both support the bushing as well as allow the threading tool a safe area to stop work after a pass.

Pictures to follow...


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## erikmannie (Feb 27, 2020)

I bored the first bushing to .879” for this 1", 8 TPI female thread.

.879” is near the point where one would overshoot it & scrap out the part, but it is officially in the specified range.

I had planned for my groove to be a generous .500”, but the taper induced by my misuse of the boring bar increased the length of this groove.


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## erikmannie (Feb 27, 2020)

I ended up with this .001” runout after I took the workpiece out of the 3 jaw chuck. Like I said, next time it will all happen in a single chucking.


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## erikmannie (Feb 27, 2020)

Carbide insert tool centered and Dykem applied to bore:


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## erikmannie (Feb 27, 2020)

The groove went horribly. This particular HSS insert tool is incapable of reaching back and cutting a groove when it is mounted perpindicular to the face of the work. As you can see, the groove is tapered and basically just a mess. Next time I will cut a nice groove from the front (not reaching back and in). The last photo shows how the unplanned taper of this groove took up some of my work area and made for a more shallow scratch pass than I had planned:


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## erikmannie (Feb 27, 2020)

Here is a picture of the threads right before I tried the bolt for the first time. I don't have a way to measure the pitch diameter here, so I just had to keep trying the Grade 5 bolt from the hardware store.


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## erikmannie (Feb 27, 2020)

Finished nut. It is a little too tight. I should have made a few more spring passes.

It is my understanding that I can improve the surface finish on those threads by (1) lubricated light (or spring) passes and/or (2) high speed, slow feed. I don’t see how it is possible to do a high speed and slow feed with the half nut engaged.


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## erikmannie (Feb 27, 2020)

For the internal threading, the combination of the PM-1030V and this carbide insert threading tool was able to cut as deep as I wanted. .010" at the beginning, .006" near the end. Whatever I wanted, no problem. And this is with this diameter machine (.001" movement of the cross slide handwheel is a measurement of the change in radius).

I have been threading with the compound set to 30°, and I always advance on the compound. Of course, I have a zero on the cross slide that was established at the time of the spring pass.


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## erikmannie (Feb 28, 2020)

The next few posts will be the last that I can add for awhile because I will be away from my lathe for two months.

I made a second nut. The two problems I had this time were minor:
(1) I got the telescoping (snap) gauge stuck in the "safety" groove at the rear of the workpiece when I was trying to measure the back end of the bore (minor diameter). I had to unchuck the workpiece in order to get my snap gauge back. It was okay because I was just starting the precision boring. I'll never do that again!
(2) _I missed my mark on the thread dial on one of the last few passes_. I stopped the damage very quickly, and later I just faced down enough to get rid of this damage. As a consequence, my nut was a little more narrow than I had planned.

I took great care to optimize my surface finish on the threads by making a lot of well lubricated passes near the end; this includes light passes and a whole lot of spring passes.

This is my safety groove: I didn't make it deep enough, but there didn't seem to be a penalty for that. I just cut threads into the groove. I always part off this groove.


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## erikmannie (Feb 28, 2020)

I made these bushings before I realized that I should do both the precision boring and threading in a single chucking. This .003" runout was the price I paid for this lack of planning. I just increased the I.D. by a few thou which is okay because there is quite a wide range for the minor diameter, and I had wiggle room. I was still well within range when I achieved a concentric bore, and of course I left it chucked in for the threading.

These pictures mostly serve to show the price you pay for using a 3J chuck.


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## erikmannie (Feb 28, 2020)

Boring done and now the workpiece is ready for threading. Also, 8 TPI scratch pass. You can see the .500" long safety groove in both pictures.


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## erikmannie (Feb 28, 2020)

This was taken around the time I was test fitting the 1” 8TPI bolt (not shown):


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## erikmannie (Feb 28, 2020)

All done! No issues that I am aware of. I can just barely thread it by hand.


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## Thriller (Apr 5, 2020)

Thanks for taking us all through your learning journey. I have learned quite a bit. What do you use for a DRO?


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## erikmannie (Apr 5, 2020)

Thriller said:


> Thanks for taking us all through your learning journey. I have learned quite a bit. What do you use for a DRO?



One of my main purchasing requirements was a factory DRO, so my lathe came with a factory installed DRO.


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