# Learning to dial in a 4-jaw



## DavidR8 (Feb 1, 2020)

I got the 4-jaw mounted up on the new backplate today and so tried my hand at chucking up some round stock.

It was a bit frustrating as I struggled to start from a place where the shock was even reasonably centered so my indicator was spinning round like a top.

I was using the rings scribed on the face of the chuck and eventually got it dialed in to about thou of runout but it took me probably 10 minutes of fussing.

Part of the problem is the my mag stand is a piece of rubbish so I was struggling to get the thing to stay put.

Any tips on the dialing in part?


Sent from my iPhone using Tapatalk


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## mmcmdl (Feb 1, 2020)

It gets easier with time Dave .


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## darkzero (Feb 1, 2020)

If the part is not perfectly concentric or has surface finish issues, 4 point it. Meaning instead of chasing the max highs & min lows on the indicator which could be false, adjust at each jaw comparing to the opposing jaw. Set zero on the indicator, whatever the difference is from the opposing jaw, adjust half the difference.

Also, when dialing in the OD, remember "tighten the highs, loosen the lows" (pinion). Vice versa for ID.


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## middle.road (Feb 1, 2020)

Watch Abom & Tom Lipton's videos.
Adam is a master at it.
I think that there is one video of a bar Z - where they had a contest to see who was quickest and they had a gag wrench for Adam to use.
Proper equipment is a requirement.


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## gr8legs (Feb 1, 2020)

For a first go at chucking something in a 4-jaw, 10 minutes may be a world speed record. (IMO)

Good start!

Stu


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## mikey (Feb 1, 2020)

I have a few. 

Make a mount for your DI that fits on your QCTP. You can make something that fits into a standard tool holder so you can adjust the height to get the tip of the DI on center. This is really important. 
Use two wrenches to adjust two opposing jaws at the same time; much faster and easier to work like this. 
Look at centering as working with two pairs of jaws. Turn the chuck and look for the pair closest to the max deviation and adjust those first. Once you get that pair close to center, the other two will be easy to do.
Once you're as dead on as you want, go around and make sure each screw has about the same amount of torque on it. Believe it or not, if one is loose that part can move.
Be patient. Centering a part accurately takes skill, and skills take time to build. The more you do it, the faster you get.
When I was a baby hobby guy, I remember spending weeks learning to dial a part in. Now I can dial in a part to zero, and I mean zero, in less than half the time it took me way back then. Hang in there.


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## tweinke (Feb 1, 2020)

I'm thinking practice makes perfect. You will get faster/ better with practice. On my 3in1 machine chuck changes are a pain so I put the four jaw on and forced myself to use it for all work for awhile.  Now when I put the four jaw on it doesnt seem so time consuming but still takes a bit to have it feel like I'm quick at it again, but at least I don't feel like I'm chasing my tail like the first time.


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## middle.road (Feb 2, 2020)

darkzero said:


> If the part is not perfectly concentric or has surface finish issues, 4 point it. Meaning instead of chasing the max highs & min lows on the indicator which could be false, adjust at each jaw comparing to the opposing jaw. Set zero on the indicator, whatever the difference is from the opposing jaw, adjust half the difference.
> 
> Also, when dialing in the OD, remember "tighten the highs, loosen the lows" (pinion). Vice versa for ID.


40 years mucking around with this stuff and I don't think I've ever heard that phrase.


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## Bi11Hudson (Feb 2, 2020)

The quick and dirty method is to align it by eye to start, then rotate the chuck by hand, then use a piece of chalk held against something solid. Once the chalk shows it centered, then use the dial indivator. I learned on a 4 jaw, it was slow going at first. Speed comes with time and experience. There is no easy way that I know of, you just have to keep doing it.
Some people use two chuck wrenches, on opposing jaws. I think they are pros that do it on a regular basis. For the occasional user, it takes me longer to set up that way. I stick to what I learned way, way back.
For roughing and most general work, I use a 3 jaw.(now) But for something that needs dead center and *must start *dead center, the 4 jaw is my fall back.
Sorry I can't be more specific, time and experience I cannot pass on through text.

.


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## DavidR8 (Feb 2, 2020)

WOW!
That help came quicker than calling an ambulance, you all are awesome!

Ok... 4-point it. That makes sense to me.
@mikey thank you for "look for the pair closest to the maximum deviation" This is super helpful as somehow I was expecting the runout to be conveniently located at a jaw, not in between  
I'm going to figure out how to make a tool holder for my indicator. Without a mill Hmmm.


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## darkzero (Feb 2, 2020)

middle.road said:


> 40 years mucking around with this stuff and I don't think I've ever heard that phrase.



That's what I was taught, that phrase was burned into my mind, remembering that alone has made it much easier for me.

The very first project in that machining course, well second project, first to use the mill, was a C-clamp. The way he taught to set the part in the vise & direction to make the cut made it easy for me to remember climb vs conventional cutting. To this day I still picture that part if I ever get confused.


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## mmcmdl (Feb 2, 2020)

First month in a real shop I had the task of mounting a very large cam in a 4 jaw on a universal grinder to grind the bore to size . Didn't end up very well as the cam fell out onto the machine and floor , smashing my boss's indicator and mag stand to pieces in the process . The other boss thought it was quite funny though . When doing irregular shapes ( cams , eccentrics etc ) always keep a small amount of pressure on the opposing jaw , or things can go south in a big hurry !


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## MontanaLon (Feb 2, 2020)

gr8legs said:


> For a first go at chucking something in a 4-jaw, 10 minutes may be a world speed record. (IMO)
> 
> Good start!
> 
> Stu


Ton of truth here. I remember my first time with a 4j, I started on it at the beginning of class and when the bell rang for clean up time 50 minutes later I had just gotten it down to .001. I got detention that day for the blue streak that came out of my mouth when I realized I had to pull my part out to start over the next day.


DavidR8 said:


> WOW!
> That help came quicker than calling an ambulance, you all are awesome!
> 
> Ok... 4-point it. That makes sense to me.
> ...


Indicator holder for a QCTP quick and dirty without a mill. Take a chunk of aluminum 1/2" thick and long enough to span the distance between 2 of the set screws that hold the tool in the holder. 1" should be plenty. Now drill a hole the size of the indicator shaft through it. A little oversize so the shaft will fit through, then drill and tap a hole 90* to it for a set screw to hold the shaft. You will have to relieve the aluminum to give clearance for the indicator but you can do that with a hack saw.

Picture attached with the parts in relation to each other. I couldn't find my first model which was replaced with a milled model that took a couple hours to do and does exactly the same thing.

The piece of aluminum goes into the tool holder and lets you use the indicator in a very solid mount.


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## Shootymacshootface (Feb 2, 2020)

Alot of great info here ready. Two things that helped me out. One was numbering the jaws with a sharpie where I could easily see the numbers. That will help with number two, make sure when you start getting close to zero that you aren't chasing your tail by taking too big of a swing at the bullseye.


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## DavidR8 (Feb 2, 2020)

Shootymacshootface said:


> Alot of great info here ready. Two things that helped me out. One was numbering the jaws with a sharpie where I could easily see the numbers. That will help with number two, make sure when you start getting close to zero that you aren't chasing your tail by taking too big of a swing at the bullseye.


That's precisely what I was doing today. Got down to a three or four thou and lost track of what jaws I was working on and ramped it back up to 10-15 thou! Grrr


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## mmcmdl (Feb 2, 2020)

DavidR8 said:


> That's precisely what I was doing today. Got down to a three or four thou and lost track of what jaws I was working on and ramped it back up to 10-15 thou! Grrr



Work 2 at a time . This is what Will was talking about in an above post . Bring them into 0-0 and bring your other 2 in to 0 . If your part is out of round , you may have .000 and .002 on opposing jaws , but the part is centered .


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## mikey (Feb 2, 2020)

Not sure what the value in numbering the jaws is. If you work in pairs (as the guys have been telling you) the indicator will tell you which pair needs work. I don't even look at the jaws; I look at the indicator.


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## mmcmdl (Feb 2, 2020)

Easiest method for 4 jaw chuck . Measure your part , find the rings on the chuck closest to the known part diameter . Set jaws to that ring . Turn in each jaw either 1 full turn , 1/2 turn , doesn't matter , until your part is tight . You're in the ballpark , then bring in your indicator and indicate as above . If the part is square or rectangular , do it the same way . Figure out your offsets and set the jaws close and move on .


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## DavidR8 (Feb 2, 2020)

Dopey me @mmcmdl, I didn't even think to measure the part


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## mmcmdl (Feb 2, 2020)

One thing no one has mentioned . If you're picking up a finished diameter with a machined face , you NEED TO GET THE FACE RUNNING TRUE FIRST ! If you don't , you'll be chasing your tail forever .


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## mmcmdl (Feb 2, 2020)

Being it's a slow night in here …………………….Dave , check out Will's mag chuck ( if he'll post a pic of it ) . These are cool pieces if you could use them . I used them all the time on our cylindrical grinders without an issue . On a lathe , you may have to be gentile with them , but they are useful none the less .

Some more of your $$$$$ we're helping you spend !


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## DavidR8 (Feb 2, 2020)

D@mn you!


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## mmcmdl (Feb 2, 2020)

DavidR8 said:


> D@mn you!



We're here to help !


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## mikey (Feb 2, 2020)

mmcmdl said:


> Being it's a slow night in here …………………….Dave , check out Will's mag chuck ( if he'll post a pic of it ) . These are cool pieces if you could use them . I used them all the time on our cylindrical grinders without an issue . On a lathe , you may have to be gentile with them , but they are useful none the less .
> 
> Some more of your $$$$$ we're helping you spend !



WAIT!!! Before you buy a mag chuck, buy a milling machine! You know, the thing that you don't have room for? If we're going to spend your money let's get serious about it. You see, a mag chuck is a want; a mill is a NEED!!!!!


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## DavidR8 (Feb 2, 2020)

@mikey typed the words right out from under me!


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## mmcmdl (Feb 2, 2020)

My bad . I had assumed we had him sold on the mill already . I jumped the gun .  Dave ! Buy that mill ………………………….then get that mag chuck .


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## DavidR8 (Feb 2, 2020)

I'm soooo close to buying a mill!


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## mikey (Feb 2, 2020)

Between Will, Dave and me, we are going to take you waaay deep into the wabbit hole! It's all in good fun but we're kinda' half-way serious about it ...


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## MontanaLon (Feb 2, 2020)

DavidR8 said:


> I'm soooo close to buying a mill!


You need a DRO for it, if you order now there is a good chance everyone in China will be dead by the time it arrives.


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## darkzero (Feb 2, 2020)

mmcmdl said:


> Being it's a slow night in here …………………….Dave , check out Will's mag chuck ( if he'll post a pic of it ) . These are cool pieces if you could use them . I used them all the time on our cylindrical grinders without an issue . On a lathe , you may have to be gentile with them , but they are useful none the less .
> 
> Some more of your $$$$$ we're helping you spend !



Oh, you know I have no problem posting pics to help people spend their money!  But.....



mikey said:


> WAIT!!! Before you buy a mag chuck, buy a milling machine! You know, the thing that you don't have room for? If we're going to spend your money let's get serious about it. You see, a mag chuck is a want; a mill is a NEED!!!!!



As Mike says, a mag chuck for the lathe is definitey a luxury item, can live without even. Mill definitely comes first as well as getting it tooled up.

So I'll just post a link. Up to David if if he want's to make the mistake of looking at it. 









						Yuasa Round Magnetic Chuck for Lathe
					

Some of this is from the other thread here. Mainly adding to my archive.  Got a 6.3" Yuasa round magnetic chuck a while back to use on the lathe. Mainly to work on thin parts & machine parts flat (parallel on both sides). Not meant to take heavy cuts (think surface grinder), just light skimming...




					www.hobby-machinist.com
				




And don't go clicking on other threads in my projects section. They're pic heavy which is intentional for the purpose of temptation.


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## mmcmdl (Feb 2, 2020)

I view that wabbit hole the same as a road trip to nowhere special . Go out and explore , enjoy the trip , learn new things , it always leads to new interests .


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## DavidR8 (Feb 2, 2020)

Oh crap... I clicked on th.......e........o.......t..........h..........e..............r................t...................h..................e.................a......................d....................s!


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## mattthemuppet2 (Feb 2, 2020)

best tip I was ever given for centering work in a 4 jaw was to get a 2nd key for the chuck. Then use the rings (or edges of the jaws relative to the body), get it close, work in pairs (one key in each jaw) and halve the difference. A DI or DTI in a tool holder helps alot, but isn't essential. You'll get it down to less than a minute in no time.


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## mmcmdl (Feb 2, 2020)

DavidR8 said:


> Oh crap... I clicked on th.......e........o.......t..........h..........e..............r................t...................h..................e.................a......................d....................s!



Uh oh ………………….there goes this years tooling budget .


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## cathead (Feb 2, 2020)

Try this if so inclined:


Indicate off the top of the part using a mag base and indicator.  Rotate the chuck for the lowest indication and loosen the top screw what is
determined to be half the error.  Rotate the chuck one half turn and tighten the top screw.  After 4 to 5 adjustments, one is usually within
10 thousandths or so.  If the low appears in between the screws, loosen both screws nearest the indicator, Rotate 1/2 turn and tighten
both screws. At that point, the part(if so inclined) will not dislodge from the chuck.  Once down to a couple thou, I look for the high spot and
tighten the top screw for a last nudge or two.  All the screws may not end up tightened exactly the same but that's not critical as long as
all are tight within reason.  Also, it isn't necessary to ever look at the numbers on the indicator, just the lows and highs to ascertain the next move.
It works for me.


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## Janderso (Feb 2, 2020)

Cat head makes a good point, I’ve stumbled along and found moving half the distance reduces the tail chasing.
My first four jaw set up was in 1973. Mr. Wade was standing over my shoulder so I bet it went fairly well.
My second time was in 2018. It took more than ten minutes!.
David, here is my rendition of Mr. Pete’s qctp indicator mount. It helps!


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## ThinWoodsman (Feb 2, 2020)

DavidR8 said:


> Part of the problem is the my mag stand is a piece of rubbish so I was struggling to get the thing to stay put



Get a Noga. It really makes a huge difference.

As for the actual dialing-in process, sounds like you are doing just fine. The above advice is all good.


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## WCraig (Feb 2, 2020)

DavidR8 said:


> I'm going to figure out how to make a tool holder for my indicator. Without a mill Hmmm.


I found a design on Thingiverse and 3D printed one:














						Thingiverse - Digital Designs for Physical Objects
					

Download files and build them with your 3D printer, laser cutter, or CNC. Thingiverse is a universe of things.




					www.thingiverse.com
				




It mounts on my QCTP (0XA size) and I have a dedicated dial indicator in it.  Mounts in seconds and is always on centre.  Makes truing up the 4-jaw much less painful!

Our local library branches have 3D printers available by the hour ($4).  The holder took a long time to print--can't remember exactly but I think it was 4+ hours.  Still, it was by far the fastest way to a decent holder for little money.

Craig


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## cathead (Feb 2, 2020)

Indicating from the side of the chuck forces one to make all the adjustments from the side.  I find that inconvenient.


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## Cadillac (Feb 2, 2020)

Wanna drive yourself crazy pull out a tenths gauge. I've found that numbering the jaws and taking your reading at the jaws not in between the jaws will help a lot. Once you get a feel for how much to loosen and tighten the jaws you will become faster. You don't want to muscle down on the jaws till your within a thou. Get Within a thou and you can usually just tightening the jaws to get ya perfect.


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## cathead (Feb 2, 2020)

Maybe we need a special dial indicator for dialing in a 4 jaw chuck with no numbers(just a white face and a needle).  
There are no numbers on the chuck key so why would numbers on the indicator have any importance?


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## projectnut (Feb 2, 2020)

mikey said:


> I have a few.
> 
> Make a mount for your DI that fits on your QCTP. You can make something that fits into a standard tool holder so you can adjust the height to get the tip of the DI on center. This is really important.
> *Use two wrenches to adjust two opposing jaws at the same time; much faster and easier to work like this.*
> ...



I would once again agree with Mikey.  Using 2 wrenches will greatly simplify and reduce the time to center a work piece.  The only caveat is that for short guys like me it only works for chucks 8" in diameter or less.  Trying to reach over a 10" or 12" chuck is more of a PITA than it's worth.  As for numbering the jaws it isn't necessary, but does come in handy (especially for us short guys) when using only 1 wrench or when the chuck is disassembled for cleaning.  

I can't tell you the number of times I was centering a part and someone started talking to me.  It always seems to happen just after adjusting 1 jaw and starting to rotate the chuck to do the opposite jaw.  You look over your shoulder and don't pay attention as to whether the chuck has spun less than or more than 1/4 turn.  For that reason alone all the chucks and all the jaws are numbered.  In addition I have a PULF (made in Poland) chuck that came with the Sheldon lathe.  When I first tried it the thing was nearly impossible to adjust within .001" to say nothing about trying to adjust it to .0001"  Upon removing the jaws I found they were not in the positions marked on the body.  I cleaned them and reinstalled them according to the markings on the body, and it now works perfectly.  I'm not sure if it was a problem with dirt, swarf, or misalignment.  I do know that now it can be adjusted to within .0001" with no problems.

As for buying additional tooling, it's easy to think that a new toy will solve all your problems.  The fact of the matter is in most cases it not only doesn't solve the immediate problem, but rather adds additional problems to the mix.  Again I've purchased a number of "used" tools that were all "but new in the box" simply because the original owner bought them convinced they would solve a problem.  In reality they didn't and were put on the shelf.  Eventually they were sold for a fraction of their original cost because they ended up as dust collectors.

In my shop I tend to over research different methods to resolve a problem.  Rather than spend money on something I think might solve the problem I first look for unique ways to use existing tooling and machinery to accomplish the task at hand.  This is in all likelihood a product of my experiences at work.  I was amazed and sometimes dumbfounded at the resourcefulness of the old German tool & die makers in our shop.  Nothing seemed to phase them.  They treated every "problem" as a challenge to their skills.  Never once did I see any of them fail to ventually overcome a problem.  Sometimes it took more than 1 try, but in the end they always succeeded.


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## rust rescue (Feb 2, 2020)

On the chucks I used during my career I found that for the initial rough-in after mounting I didn't have to read the indicator values, just the swing of the needle. When making an adjustment the movement of the chuck wrench usually is very close to the needle movement. Just tighten or loosen Half of the needle movement. This was using a Starrett back push indicator. Got a Noga indicator mount my last few years of paid work. The best! Wish I had had one for the first 30. 
   Keep at it. Soon you will find the 4-jaw almost as fast as a 3-jaw and always zeroed out.


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## tech610 (Feb 2, 2020)

Not my original process, but I can't find the link:
You are using a DI for this process and the two chuck keys.
1.get as close as you can to center the workpiece.
2. find the lowest point and zero it.
3. find the highest point 
4. find the middle point and zero it.
5. now go to the next jaw and adjust to zero
 and so forth until you are centered


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## BGHansen (Feb 2, 2020)

My dad was a shop teacher and taught the 2-chuck key method.  He'd marked the face of the chuck next to the jaws with "A1, B1, A2, B2" going around the chuck.  Set the stock in the chuck and ran the jaws to loose contact.  Used a dial indicator on a mag base (no QCTP's in those days) and swept A1 to A2.  Zero'd on A1 and flipped to the opposite side so A2 was at the indicator.  Then adjusted both jaws to take A2 half-way to zero.  Reset to Zero on A2 and rotated back to A1 for confirmation.  He'd get within a couple thousandths pretty quickly, then did B1/B2.  For the final adjustment, he'd just tighten one jaw to hit zero.

For square stock, he'd use a couple of methods.  One was basically the same as that above, but he had the kid roll the chuck back/forth slightly to find the low point at the indicator.  Zero out, pull back on the indicator so it's off the work and rotate the chuck 180.  Do the slight roll back/forth to the low point and leave the chuck there.  Then do the two chuck key adjustment to half-way to zero.

Other method was to have the student use a square or surface plate and height gauge to scribe the center point of the square stock.  Then center punch it by eye.  Mount it in the chuck and put a wiggler with a sharp point in the tail stock, engage the wiggler end into the center punched hole.  Then use the procedure at the top with the wiggler in the center punched hole, indicator on the wiggler probe shaft to find center.  He used this same method for oddball stuff like an eccentric hole.

Once you do it a few times it goes pretty quickly.  You'll easily get dialed in within 0.0005" within a few minutes with practice.

Bruce


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## middle.road (Feb 2, 2020)

From the "Dept of the Easily Distracted & Confused", number the jaws...


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## Norseman C.B. (Feb 2, 2020)

QCTP Flip and twist Indicator holder
					

Finished my holder today and likin it !!




					www.hobby-machinist.com
				




This may be useful to you..............Since your being aided in buying a mill...........................


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## BGHansen (Feb 2, 2020)

middle.road said:


> From the "Dept of the Easily Distracted & Confused", number the jaws...


Yeah, the life of a shop teacher, good day was when everyone went home safely.  I recall him being frustrated at times with student's test scores. He'd give them a drawing of a ruler in 1/16" grads and label 20 points. Student was asked to write the measurements in lowest term fractions. He put examples right on the test like 8/16 =1/2. He rarely had a student get them all right. We'd wonder how some would ever get through life, but he'd see former students years later and they all finally got it. Can't assume anything when teaching newbies around machinery. Thirty years as a shop teacher and he only had two students suffer minor injuries.

One was a student had drilled a hole in an aluminum shift knob for his car. He used a major diameter drill for a tap drill instead of the correct one. My dad suggested he try filling the hole with lead, then drill and tap. The student washed the knob and had some water in the bottom of the hole. Naturally the water steamed and spattered the lead for a minor burn.

Other student was really lucky. Dad told students to not leave stock beyond the head stock of the lathe. He had some crotch supports for that work, but didn't have the students use them. "Cut the stock so it doesn't hang out". A student left stock out, probably 1/4" or so, and it bent while turning.  Dad saw the lathe shaking and hit the master power. The kid reached out to stop the stock before the lathe stopped. He ended up with a pretty good bruise, could have been a lot worse.

Bruce


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## homebrewed (Feb 2, 2020)

Making a second chuck key is a nice little project in itself.  I used an RT on my mill to cut the square end but it can be done entirely on a lathe if you have a milling attachment.  Or failing that, some careful file work will do the job.


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## ttabbal (Feb 2, 2020)

Let me know if you want a printed QCTP indicator holder. I don't mind letting the printer run a bit for you. I might set it up with hot pink filament, depends on the mood at the time...


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## DavidR8 (Feb 2, 2020)

ttabbal said:


> Let me know if you want a printed QCTP indicator holder. I don't mind letting the printer run a bit for you. I might set it up with hot pink filament, depends on the mood at the time...



Gosh, that would be fantastic!


Sent from my iPhone using Tapatalk


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## ttabbal (Feb 2, 2020)

DavidR8 said:


> Gosh, that would be fantastic!
> 
> 
> Sent from my iPhone using Tapatalk



What size is your QCTP?


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## DavidR8 (Feb 2, 2020)

ttabbal said:


> What size is your QCTP?



It’s an AXA


Sent from my iPhone using Tapatalk


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## plunger (Feb 2, 2020)

The easiest way to learn a 4 jaw.  . Hide your three jaw for a month.....


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## mikey (Feb 2, 2020)

plunger said:


> The easiest way to learn a 4 jaw.  . Hide your three jaw for a month.....



Have someone else hide it. If I hid it, I'd know where it is and go get it!


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## Grinderman (Feb 2, 2020)

DavidR8 said:


> I got the 4-jaw mounted up on the new backplate today and so tried my hand at chucking up some round stock.
> 
> It was a bit frustrating as I struggled to start from a place where the shock was even reasonably centered so my indicator was spinning round like a top.
> 
> ...


I made this little tool for the 4 jaw. It has all the common sizes I normally use (1/4, 3/8, 1/2 and 3/4”). I chuck it into the tailstock and run it up into the 4 Jaw. You can then close the jaws down on the size needed, loosen the jaws slightly, remove the tool and install the actual part. Gets you real close.


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## epanzella (Feb 2, 2020)

It sounds like you're spending too much time while the part is a mile off. I stick ANY tool is the tool holder and run it up to the part. Spin the part in the chuck (BY HAND) until you touch a high spot. Rotate to the opposite jaw and eyeball to cut the space in half. When the space is roughly even with jaws 1 & 3 do the same with jaws 2 & 4. Now when you grab the DI it will be within one rotation (.100") of the dial and will be easy to figure out using what every one has said in this thread. It's also a good idea to have 2 short opposing chuck keys.  I made mine by just welding some appropriately sized keystock into a "T". Others on the board have made works of art. Whatever floats your boat.
(edit; added BY HAND in line #2)


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## Norseman C.B. (Feb 2, 2020)

When I was doing my apprenticeship we were only allowed to use a three jaw for production jobs
and if you didn't hit close to the bosses bid time you got an a$$ chewin, so dialin in a four jaw quickly
was priority one ................


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## Mini Cooper S (Feb 2, 2020)

Someone may have mentioned this, but I didn't see it so here goes.
Right after I bought my first lathe, I turned some concentric grooves in the face of the 4 jaw chuck. I put them about every 3/8 inch but you can space them as you see fit. You can use a corner or edge of the jaws and the lines to get the work piece very close to true, saves a lot of guess work.


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## Chewy (Feb 2, 2020)

David, get a piece of 1/2" key stock.  Drill the 3/8" hole back about 9/16-5/8". Flip 90 degrees and drill #21 tap hole for 10/32 screw about 1/4" from end.  Tap it. Hacksaw a cut across the 3/8" hole so it closes with screw. Drill one side of tapped hole with #10 or 11 drill to remove threads.  Install indicator and mount in AXA holder.  No mill needed, just 3 drill bits, a hacksaw and some kind of drill.

Mine is approximately what i said except that both ends are done and I use two indicators.  By switching positions I can dial the face also.


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## DavidR8 (Feb 2, 2020)

Mini Cooper S said:


> Someone may have mentioned this, but I didn't see it so here goes.
> Right after I bought my first lathe, I turned some concentric grooves in the face of the 4 jaw chuck. I put them about every 3/8 inch but you can space them as you see fit. You can use a corner or edge of the jaws and the lines to get the work piece very close to true, saves a lot of guess work.
> 
> 
> View attachment 312426


I'm somewhat embarassed to say that my chuck has lines on it. Duffus here didn't think about measuring the stock and using the lines a guide.


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## middle.road (Feb 2, 2020)

DavidR8 said:


> I'm somewhat embarassed to say that my chuck has lines on it. Duffus here didn't think about measuring the stock and using the lines a guide.


Don't feel like you're the first one to have that happen to.


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## MontanaLon (Feb 3, 2020)

Here it is, the quick and dirty indicator holder for the AXA tool post. No mill necessary.


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## DavidR8 (Feb 3, 2020)

Thanks @MontanaLon I have some 1/2" phenolic that I could use for that!


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## tq60 (Feb 3, 2020)

Now you have seen that then many other ideas.. 

Different angles and other things.

Remember to move 1/2 way to target.

Often you forget which way to go, touch the DI probe and see which way it moves so you know which way to turn screws.

You need to loosen before tighten and after time you will get a feel for how much to turn for 0.010...

When you get close you reverse and tighten first as it just needs a touch.

Sent from my SAMSUNG-SM-G930A using Tapatalk


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## rwm (Feb 7, 2020)

I am considering making 2 short keys for dialing in the 4 jaw. Any recommendations on the length of the key or the handles? Anyone got an example? What kind of steel would you use? Does it need to be hardened?
I know this was covered somewhere but the forum does not allow one to search for the word "key"! I guess it is too short a word!
Robert


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## MontanaLon (Feb 7, 2020)

They don't need to be long and in fact shorter is probably better as you will have to reach both of them at the same time. You don't want it hardened, better to have the key damaged from the screw than the screw damaged by the key. I used a scrap piece of mild steel but anything would likely serve as long as you don't do any hardening.


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## epanzella (Feb 7, 2020)

rwm said:


> I am considering making 2 short keys for dialing in the 4 jaw. Any recommendations on the length of the key or the handles? Anyone got an example? What kind of steel would you use? Does it need to be hardened?
> I know this was covered somewhere but the forum does not allow one to search for the word "key"! I guess it is too short a word!
> Robert


Check for the size square stock that fits your chuck (mine is 3/8") and pick it up at Home Depot. Weld into a T.  Make them small enough so that you can spin them without hitting your headstock.


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## DavidR8 (Feb 7, 2020)

rwm said:


> I am considering making 2 short keys for dialing in the 4 jaw. Any recommendations on the length of the key or the handles? Anyone got an example? What kind of steel would you use? Does it need to be hardened?
> I know this was covered somewhere but the forum does not allow one to search for the word "key"! I guess it is too short a word!
> Robert



You read my mind!


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## mikey (Feb 8, 2020)

Got some 303 SS and collet blocks? Simple to make, doesn't rust and easy to machine. I suggest making at least one shorter for use on the far side of the chuck; just enough for your knuckles to clear. Make the part that goes into the chuck a close fit and chamfer the edges and it will work for a very long time.


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## Tozguy (Feb 8, 2020)

rwm said:


> I am considering making 2 short keys for dialing in the 4 jaw. Any recommendations on the length of the key or the handles? Anyone got an example? What kind of steel would you use? Does it need to be hardened?
> I know this was covered somewhere but the forum does not allow one to search for the word "key"! I guess it is too short a word!
> Robert


These keys were made up from plumbing fittings found at the local hardware store. They are only used to finger tighten the jaws into position so they do not have a hard life. These have been used for several years now. Once you have the right size pipe plug (this one is 1/4 pipe with a 3/8 square) there are several options for the other parts to get the length and diameter that suits you.



Another idea is to get a piece of square key stock, cut it to length and press a piece of thick hose over it for a grip.


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## projectnut (Feb 8, 2020)

Keep in mind when making your "keys" that you'll be machining stock of varying diameters.  The keys should be long enough to clear the jaws and leave enough room for your hand to grip them when the jaws are at their maximum diameter.  Short keys work well when the jaws don't extend beyond the body of the chuck, but it hurts like hell when you're opening a jaw and you smack you're knuckles against it because the key is too short.


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## rwm (Feb 8, 2020)

Thanks for these great ideas! I have some 304 and a collet block. The jaws on my Southbend chuck are very stiff. I could not turn the adjusters with that small diameter plumbing tool. Using the plugs is a great idea however. I am thinking of making the keys about 2.5" long with similar length handles. The easiest way would be to put a handle on some square stock I suppose....
I could turn the end of the square stock round and then solder it into a handle...
Robert


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## Grinderman (Feb 8, 2020)

rwm said:


> Thanks for these great ideas! I have some 304 and a collet block. The jaws on my Southbend chuck are very stiff. I could not turn the adjusters with that small diameter plumbing tool. Using the plugs is a great idea however. I am thinking of making the keys about 2.5" long with similar length handles. The easiest way would be to put a handle on some square stock I suppose....
> I could turn the end of the square stock round and then solder it into a handle...
> Robert


I’ve been using these stubby 3/8 ratchet handles and extensions for years on my 4 jaw. A t-handle was always in the way on the backside. Pretty cheap to buy no name stuff at the big box stores.


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## rwm (Feb 8, 2020)

I have a key that is about .332" or 8.4mm. What is the nominal dimension of this key? It falls between 5/16 and 3/8". Is it a metric 8.5? I have not seen that.
Robert


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## mikey (Feb 8, 2020)

The key for my Emco/Rohm chuck is 0.35"/8.9mm. Wierd. The good thing is that you can make it whatever you want.


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## rwm (Feb 8, 2020)

mikey said:


> The key for my Emco/Rohm chuck is 0.35"/8.9mm. Wierd. The good thing is that you can make it whatever you want.


Sure can!
I'm thinking about 2 of these as a key handle:


Apologies to David for the thread abduction!
Robert


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## DavidR8 (Feb 8, 2020)

No worries @rwm, I’m soaking up the knowledge! 


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## mikey (Feb 8, 2020)

rwm said:


> Sure can!
> I'm thinking about 2 of these as a key handle:



Might be a little challenging to get enough torque with those. I was going to suggest T-bars long enough to get some leverage because you'll need it.


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## Tozguy (Feb 9, 2020)

The original T wrench that came with the chuck can still be used for the last step of fine adjustment and torquing the jaws.
My twin stubby wrenches are only used get the jaws quickly in position to receive the work and then finger tighten the jaws to center the work as close as my eyeballs can make it. Then an indicator is installed and the single T wrench is used to finish the job.
Knurled surfaces on the stubby wrenches offer sufficient grip for my fingers and the jaws move easily when there is no pressure on them.


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## Tozguy (Feb 9, 2020)

rwm said:


> I have a key that is about .332" or 8.4mm. What is the nominal dimension of this key? It falls between 5/16 and 3/8". Is it a metric 8.5? I have not seen that.
> Robert


Would it not be better to measure the sockets? The fit of the original keys that came with my lathe were on the loose side. I would not use them as a model when making a new wrench.


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## rwm (Feb 9, 2020)

That knurled knob has a 2" OD. Yes I would use the original wrench for the final tightening. My key fits very nicely so duplicating it would be perfect. I still do not understand the nominal size it is supposed to be!
Robert


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## projectnut (Feb 9, 2020)

rwm said:


> Sure can!
> I'm thinking about 2 of these as a key handle:
> View attachment 313075
> 
> ...



What size chuck are you intending to use these keys on?  Most of my 4 jaw chucks are in the 8" to 12" range.  I doubt I could get enough leverage on a 2" diameter knob to even  move the jaws let alone snug them in place.  About the only ones  I can see them working on are a couple 4,  5" ones, and an 8" one for the Seneca Falls lathe.  The jaws on the 4" and 5" ones are pretty small.  The 8" one is worn to the point the jaws sound like  castanets when the chuck is rotated without anything in the jaws.


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## Tozguy (Feb 9, 2020)

rwm said:


> I have a key that is about .332" or 8.4mm. What is the nominal dimension of this key? It falls between 5/16 and 3/8". Is it a metric 8.5? I have not seen that.
> Robert


I have not seen an 8.5 chuck key either.
The socket on my 8'' four jaw measures .407''. The key measures .393''. I consider the fit to be very good.
The DIY stubby keys I made up measure .374'' and work well for what I do with them.
May I ask why you need to determine the nominal dimension of your key?


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## Tozguy (Feb 9, 2020)

rwm said:


> Sure can!
> I'm thinking about 2 of these as a key handle:
> View attachment 313075
> 
> ...


My thanks to David for his positive attitude.
rwm, those should work great for some finger wrenches. If they don't then your chuck would need some maintenance or troubleshooting.
As previously mentioned by projectnut your keys would have to be long enough for the knurled section to clear the top of the jaws in their safe full open position. Sorry to mention the obvious.
In my case I traded off some of the length required to fully open jaws in order to have more compact tools for the smaller dimensions I usually have to chuck.


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## rwm (Feb 9, 2020)

The chuck in question is a 6" Southbend brand. It is new and made in Taiwan so I am expecting metric. There is really no reason I need to know the nominal dimension since I will duplicate the key, I was just curious if the size was made to a standard. The jaws are tight but I believe a 2" diameter will be enough to turn the adjuster. 
My next task will be to figure how to attach the stem to the knob. I have a few ideas including cross drilling with a roll pin. I could braze it but would likely discolor the knurl and have difficulty cleaning it. Epoxy would likely hold for this application especially if I sandblasted the surfaces first. FYI the knob is reamed to .500". I would have made these but I have a knurling disorder especially on stainless!
Robert


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