# I just glued on my 3 jaw chuck...



## Batmanacw (Jan 2, 2021)

I have a PM 1030v and I am very pleased with it. The 3 jaw it came with showed better than average run out of around 0.003" but I noticed sometimes it would be a bit better. I tried tapping it in with the mounting nuts slightly loose and I was able to dial it in to dead nuts! This was at two different diameters!

If the adapter fit better this chuck would be amazing!

Every time I change out the chuck I'd dial it back in but it wasn't holding it anyways. I put some automatic center punch marks inside the adapter to make it tighter on the spindle and it would stay under 0.002" consistently.

Today I cleaned everything really well and rubbed paste wax and a light coat of candle wax on the spindle nose. I cleaned the adapter with acetone and applied a light coat of jb weld.

I also noticed if you don't get crazy on the mounting bolts the chuck runs truer. I'll have to figure that out later.

Anyway. Wish me luck that my chuck comes off! Lol!







Eta: if this works I'll do my collet chuck too. Its a Shars tru-set so I can dial it in. I just need a much better fit on the spindle nose if I don't want to have to dial it in each time.


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## matthewsx (Jan 2, 2021)

That seems a little extreme. Don’t most folks just use a four jaw when they need precision for a second op?

John


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## Batmanacw (Jan 2, 2021)

matthewsx said:


> That seems a little extreme. Don’t most folks just use a four jaw when they need precision for a second op?
> 
> John



....and why do they use an independent 4 jaw?


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## matthewsx (Jan 2, 2021)

Because you can dial it in exact when needed. Also good for odd shapes.

John


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## Batmanacw (Jan 2, 2021)

matthewsx said:


> Because you can dial it in exact when needed. Also good for odd shapes.
> 
> John



So why not have a dead accurate 3 jaw?  I didn't get rid of my 4 jaw. Do you know what glass bedding a rifle is? The wax is a release agent. The epoxy won't stick to it. I should end up with a very accurate removable fit.


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## Jim F (Jan 2, 2021)

The part will never re-locate exactly in a 3 jaw after it is removed.


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## Batmanacw (Jan 2, 2021)

Jim F said:


> The part will never re-locate exactly in a 3 jaw after it is removed.



Guess we will see. Huh? 


I'd be pretty excited with 0.001" repeatability.


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## benmychree (Jan 2, 2021)

I'd be pretty excited with .001 repeatability too, but it is not in the nature of 3 jaw chucks due to wear and (not so unusual) crashes, that is why they make AdjusTru chucks, 4 jaw chucks and collets.


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## Batmanacw (Jan 2, 2021)

I chucked up the gauge pin 10 times being careful not to disturb my jb weld. 

I averaged around 0.0003" run out. Better with less clamping force. I got 0.0004" as the worst. 0.0001" as the best. 

The other poster was correct. It didn't repeat flawlessly but holy smokes is that accurate for a 3 jaw.


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## Batmanacw (Jan 2, 2021)

benmychree said:


> I'd be pretty excited with .001 repeatability too, but it is not in the nature of 3 jaw chucks due to wear and (not so unusual) crashes, that is why they make AdjusTru chucks, 4 jaw chucks and collets.



My collet chuck has set-true capability. I'd still like it to be as accurate as possible so I don't have to dial it in each time I use it. I'm lazy....lol. I was disappointed that it wasn't more accurate from the factory.


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## mikey (Jan 2, 2021)

Batmanacw said:


> Guess we will see. Huh?
> 
> 
> I'd be pretty excited with 0.001" repeatability.



I'm not trying to discourage you, Batmanacw; just wanted to comment, okay?

The accuracy of all lathe work holding devices is not achieved by the spindle mount, but by the mechanism used by the chuck to hold the work. Then there is the phase of the work, either a first or second operation. 

A 3 jaw chuck is a first operation device and it will turn a nominal work piece dead on the lathe's centerline in a first op, the first time you turn it. However, for a second op where the previously turned work piece is removed from the chuck and then placed back in the 3 jaw chuck, no matter how accurate the spindle mount is the chuck will run out varying amounts depending on where on the scroll you are. This is just the nature of a scroll chuck, regardless of the number of jaws the chuck has. What's more, the more wear the chuck has, the greater the run out will be in a second op. The converse is also true; the less worn the chuck is, the less run out it will have in a second op but it will still run out too much for precision work. 

A 4 jaw independent can be dialed in precisely. This chuck can be used for both first and second operations and is the most versatile of all chucks. It is also the slowest to employ and it can mark or mar a finely finished, knurled or threaded surface so it is not a panacea. 

Collet chucks rely on the accuracy of the tapers in the chuck so concentricity of taper to the spindle matters here. Much attention is paid to how well the chuck fits the spindle mount. 

There is nothing wrong with trying for the best spindle mount for your chuck. Just understand the nature of the device you're working with.


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## mikey (Jan 2, 2021)

Batmanacw said:


> I chucked up the gauge pin 10 times being careful not to disturb my jb weld.
> 
> I averaged around 0.0003" run out. Better with less clamping force. I got 0.0004" as the worst. 0.0001" as the best.
> 
> The other poster was correct. It didn't repeat flawlessly but holy smokes is that accurate for a 3 jaw.



The way to test your thesis is to turn some nominal stock in a first op; it should have zero run out. Then remove the work piece and rechuck it and then see what you get.


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## Batmanacw (Jan 2, 2021)

mikey said:


> I'm not trying to discourage you, Batmanacw; just wanted to comment, okay?
> 
> The accuracy of all lathe work holding devices is not achieved by the spindle mount, but by the mechanism used by the chuck to hold the work. Then there is the phase of the work, either a first or second operation.
> 
> ...



I'm simply removing about 0.003" of slop in the fit. If I can throw my 3 jaw in and get 0.001" of run out consistently I'd be happy with it for 90% of the stuff I do. I've dealt with 0.005" in my old lathe for years. 

I don't do tons high precision work but I have no issues making straight parts. Lots of tricks for that.


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## rwm (Jan 2, 2021)

I have to say, my Bison 3 jaw is accurate to about .001-.002" everywhere I have checked on the scroll (various diameters). When I dial in something on the 4 jaw I have trouble getting to .001". I get the theory, but in practice I rarely change over to the 4 jaw with this chuck in the mix. 
Robert


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## mikey (Jan 2, 2021)

Batmanacw said:


> I'm simply removing about 0.003" of slop in the fit. If I can throw my 3 jaw in and get 0.001" of run out consistently I'd be happy with it for 90% of the stuff I do. I've dealt with 0.005" in my old lathe for years.
> 
> I don't do tons high precision work but I have no issues making straight parts. Lots of tricks for that.



I totally get it. We all try for the best fit of a chuck on the spindle. I just wanted to point out that with a scroll chuck, what goes on in front of the chuck does not rely much on what goes on in back of the chuck.


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## Batmanacw (Jan 2, 2021)

rwm said:


> I have to say, my Bison 3 jaw is accurate to about .001-.002" everywhere I have checked on the scroll (various diameters). When I dial in something on the 4 jaw I have trouble getting to .001". I get the theory, but in practice I rarely change over to the 4 jaw with this chuck in the mix.
> Robert



The hardest part of dialing in on a 4 jaw is not getting too tight before you have it really close. It just takes practice. I haven't even used the 4 jaw on my 1030 yet. I don't mind 4 jaws but I just haven't needed it.


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## MrWhoopee (Jan 2, 2021)

I've mentioned this before, but it bears repeating. You can dial in a workpiece in a 3-jaw using a soft hammer. Snug the part (not tight) in the chuck and indicate. Tap the high jaw with your soft hammer and snug the chuck a little tighter. Indicate again, tap the high jaw again and tighten some more. Three times is usually enough to get within .001. Working machinists are generally efficient (lazy), and this is much easier and faster than mounting a 12 in. 4-jaw.


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## Batmanacw (Jan 2, 2021)

MrWhoopee said:


> I've mentioned this before, but it bears repeating. You can dial in a workpiece in a 3-jaw using a soft hammer. Snug (not tight) the part in the chuck and indicate. Tap the high jaw with your soft hammer and snug the chuck a little tighter. Indicate again, tap the high jaw again and tighten some more. Three times is usually enough to get within .001. Working machinists are generally efficient (lazy), and this is much easier and faster than mounting a 12 in. 4-jaw.


I am fortunate that this 3 jaw holds darn straight as well as low run out. I got to my collet chuck when I can because it assists me in my laziness. Even with dialing it it only takes a couple minutes and it holds nearly dead straight. The 4 jaw will come out the moment I get an odd shaped or bigger part.


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## pacifica (Jan 2, 2021)

Batmanacw said:


> I chucked up the gauge pin 10 times being careful not to disturb my jb weld.
> 
> I averaged around 0.0003" run out. Better with less clamping force. I got 0.0004" as the worst. 0.0001" as the best.
> 
> The other poster was correct. It didn't repeat flawlessly but holy smokes is that accurate for a 3 jaw.


See what you get with different size pins.


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## ErichKeane (Jan 2, 2021)

pacifica said:


> See what you get with different size pins.


Yep, this is going to be the key.  Even a $1000 3-jaw chuck isn't consistent more than ~2-3 thou throughout its holding range.


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## Batmanacw (Jan 2, 2021)

ErichKeane said:


> Yep, this is going to be the key.  Even a $1000 3-jaw chuck isn't consistent more than ~2-3 thou throughout its holding range.



Last time I tried it I had nearly perfect results. I even mentioned it in the original post.


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## aliva (Jan 2, 2021)

Hopefully the repeatability will stay.
A lot of effort but if its works over the long run,  good for you.


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## Batmanacw (Jan 2, 2021)

aliva said:


> Hopefully the repeatability will stay.
> A lot of effort but if its works over the long run,  good for you.


I couldn't find my jb weld and acetone so I have $18 invested.... the worst part is waiting for for epoxy to cure. I'm dying to pull it off and see how it repeats.


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## Tozguy (Jan 2, 2021)

Batmanacw said:


> So why not have a dead accurate 3 jaw?  I didn't get rid of my 4 jaw. Do you know what glass bedding a rifle is? The wax is a release agent. The epoxy won't stick to it. I should end up with a very accurate removable fit.


Sounds like a good idea to me. I am sure that reducing one variable like that can only help.


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## ErichKeane (Jan 2, 2021)

Batmanacw said:


> Last time I tried it I had nearly perfect results. I even mentioned it in the original post.


I only saw you say you used a single gauge pin, so I didn't see if you tried it with a 5" pin and a 1/4" pin, etc.  As 3 jaws are tightened over time, they get 'grooves' or worn spots in the scroll that throws them off.  You can see it in any well-used 3 jaw when you take them apart.  

From my perspective, it doesn't really matter how good my scroll-chuck is, if I want to do a 2nd operation concentrically, I use a collet chuck or a 4 jaw.


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## Batmanacw (Jan 2, 2021)

ErichKeane said:


> I only saw you say you used a single gauge pin, so I didn't see if you tried it with a 5" pin and a 1/4" pin, etc.  As 3 jaws are tightened over time, they get 'grooves' or worn spots in the scroll that throws them off.  You can see it in any well-used 3 jaw when you take them apart.
> 
> From my perspective, it doesn't really matter how good my scroll-chuck is, if I want to do a 2nd operation concentrically, I use a collet chuck or a 4 jaw.



The last time I checked a second diameter I used a piece of turned material around 1" but it has been a while. 

I can be absolutely certain the accuracy will degrade over time. This is a fun little experiment to see how good it can be with very little invested other than a little time and less than $20


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## erikmannie (Jan 2, 2021)

I have a PM-1030V, & I leave the 4J installed. As easy as it is to install the 3J, I strongly prefer a 4J.

Same with my larger lathe: 4J in there, face plate on standby, 3J in a box that may never be opened as long as I live.

I know that many machinists get a lot of use out of their self-scrolling chucks. I guess I prefer repeatability over speed. I like having the option to remove a part & then chuck it up again as true as I want.

I would only use a 3J either if I were (1) sure that I would not need to remove and rechuck the part, or (2) in a big hurry. 

I would be worried about abusing my spindle bearings ever so slightly using a soft hammer to tap (and thus center) stock in a 3J.


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## silence dogood (Jan 2, 2021)

Penn Industries offers a 6 jaw chuck that is repeatable to .0005". It's a BTC Zero-Set precision. With that you don't need a collet chuck.  It costs  $3,847.00.  Hm. I think I'll pass and stick with my 4jaw and collet chucks.


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## Batmanacw (Jan 2, 2021)

silence dogood said:


> Penn Industries offers a 6 jaw chuck that is repeatable to .0005". It's a BTC Zero-Set precision. With that you don't need a collet chuck.  It costs  $3,847.00.  Hm. I think I'll pass and stick with my 4jaw and collet chucks.



Me too.....


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## erikmannie (Jan 2, 2021)

silence dogood said:


> Penn Industries offers a 6 jaw chuck that is repeatable to .0005". It's a BTC Zero-Set precision. With that you don't need a collet chuck.  It costs  $3,847.00.  Hm. I think I'll pass and stick with my 4jaw and collet chucks.



I am glad that the manufacturer’s offer the “Set-Tru” self scrolling chucks. I would never buy a self scrolling chuck that isn’t a Set-Tru or the like.

From https://en.m.wikipedia.org/wiki/Chuck_(engineering)


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## Batmanacw (Jan 2, 2021)

erikmannie said:


> I am glad that the manufacturer’s offer the “Set Tru” self scrolling chucks. I would never buy a self scrolling chuck that isn’t a Set Tru or the like.



That one  cost as much as the lathe. The Bison is a significant portion of the cost. I'm glad I got a relatively good one that isn't tru-set considering a large portion of the run out is in the crappy adapter plate.


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## erikmannie (Jan 2, 2021)

I just went out & checked the TIR on my PM-1030V.

.0005” on the spindle:







.0022” on the backing plate:






.0046” on the 4J chuck:


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## mikey (Jan 2, 2021)

Set-tru chucks are nice, and they offer the speed of a scroll chuck. You can dial a Set-tru in to pretty tight tolerances BUT it will only be super-accurate for the diameter you set it for. This really helps if you have a production run on a bunch of precision rod. However, once you change to a different diameter you have to re-set the chuck for that diameter to regain really low run out. 

There is a misconception that a Set-tru can be dialed in and it will then be accurate for ALL diameters you put in the chuck. This is not so, again because of the nature of a scroll chuck.

I own a near mint Pratt Burnerd 6 jaw Set-Rite chuck that I can dial in to about 0.0001" TIR and it will repeat that run out if I chuck up the same diameter work piece but the run out changes significantly if I use any other diameter. I can bring it back in to ridiculous run out for another diameter but it takes time. If I just set it once and use it on everything, it has about 0.001" TIR or less. Still pretty accurate but do you really need a $2,000 chuck for first operations? I don't think so. 

Personally, I use an Emco/Rohm 3 jaw the vast majority of the time for first ops and an Emco/Rohm 4 jaw for second ops. I rarely use the 6 jaw except for plastics or thin-walled pieces and I use an ER chuck even less often for polished/knurled/threaded parts.


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## Batmanacw (Jan 2, 2021)

mikey said:


> Set-tru chucks are nice, and they offer the speed of a scroll chuck. You can dial a Set-tru in to pretty tight tolerances BUT it will only be super-accurate for the diameter you set it for. This really helps if you have a production run on a bunch of precision rod. However, once you change to a different diameter you have to re-set the chuck for that diameter to regain really low run out.
> 
> There is a misconception that a Set-tru can be dialed in and it will then be accurate for ALL diameters you put in the chuck. This is not so, again because of the nature of a scroll chuck.
> 
> ...



My lathe





erikmannie said:


> I just went out & checked my TIR. .0005” on the spindle:
> 
> View attachment 349687
> 
> ...



Loosen the studs and then re-tighten and see how much the backing plate changes. Mine simply had too much play to make me happy. I fixed it.


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## Batmanacw (Jan 2, 2021)

mikey said:


> Set-tru chucks are nice, and they offer the speed of a scroll chuck. You can dial a Set-tru in to pretty tight tolerances BUT it will only be super-accurate for the diameter you set it for. This really helps if you have a production run on a bunch of precision rod. However, once you change to a different diameter you have to re-set the chuck for that diameter to regain really low run out.
> 
> There is a misconception that a Set-tru can be dialed in and it will then be accurate for ALL diameters you put in the chuck. This is not so, again because of the nature of a scroll chuck.
> 
> ...



My er40 is Set-tru. I'll most likely always need to dial it in each time I install it. I would like the fit to be better so I don't have to dial in so much.


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## mikey (Jan 2, 2021)

Batmanacw said:


> My er40 is Set-tru. I'll most likely always need to dial it in each time I install it. I would like the fit to be better so I don't have to dial in so much.



ER collet chucks are different. If you dial it in accurately and then mount it the same way every time then it should hold its run out provided you are consistent with torquing the nut and do not collapse the collet excessively. 

My ER chuck is not a set tru but it is damned accurate for what it is (about 0.0001" TIR). That is fine for any turned and ground rod I am likely to use it on and it matters very little for threaded or knurled parts.


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## Batmanacw (Jan 2, 2021)

mikey said:


> ER collet chucks are different. If you dial it in accurately and then mount it the same way every time then it should hold its run out provided you are consistent with torquing the nut and do not collapse the collet excessively.
> 
> My ER chuck is not a set tru but it is damned accurate for what it is (about 0.0001" TIR). That is fine for any turned and ground rod I am likely to use it on and it matters very little for threaded or knurled parts.



My adapter for the collet chuck has a couple thou of slop so there is no way to mount it perfect each time.....unless I can do something to remove the excess slop.


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## mikey (Jan 2, 2021)

The back plate should fit your spindle register precisely and solidly. If it doesn't then you need to address that. There should be zero slop back there.


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## Batmanacw (Jan 2, 2021)

mikey said:


> The back plate should fit your spindle register precisely and solidly. If it doesn't then you need to address that. There should be zero slop back there.


So now you get the entire point of the thread. Glad you are all caught up now.


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## KevinM (Jan 2, 2021)

This is my solution for spindle to backplate runout.


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## Batmanacw (Jan 2, 2021)

KevinM said:


> This is my solution for spindle to backplate runout.
> 
> View attachment 349709



That would be next...


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## mikey (Jan 2, 2021)

Batmanacw said:


> So now you get the entire point of the thread. Glad you are all caught up now.



Well, uhm, that point escaped me ...


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## Batmanacw (Jan 2, 2021)

mikey said:


> Well, uhm, that point escaped me ...


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## mmcmdl (Jan 2, 2021)

MrWhoopee said:


> Working machinists are generally efficient (lazy), and this is much easier and faster than mounting a 12 in. 4-jaw.



I resemble that !


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## stupoty (Jan 3, 2021)

silence dogood said:


> Penn Industries offers a 6 jaw chuck that is repeatable to .0005". It's a BTC Zero-Set precision. With that you don't need a collet chuck.  It costs  $3,847.00.  Hm. I think I'll pass and stick with my 4jaw and collet chucks.


thats a bargain , can u get me two of them I will be round latter for um , ha ha ha 

Stu


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## Batmanacw (Jan 3, 2021)

I had good but mixed results. The wax worked perfectly. The jb weld is allowing easy but snug installation. 

The 0.5" gauge pin went right back to dead nuts upon installation and re-chucking. I was stoked!

As I chucked up on bigger pieces I saw more run out so I checked the body. 0.002" run out so I marked it. The body run out and the bigger (1.5") part run out had correlation. I carefully sanded the jb weld to allow the chuck to move 0.001" in the right direction. Now I have 0.001" of run out on the 0.5" gauge pin, 0.0015" at 0.860", and 0.0015" at 1.5". 

I am quite pleased with the results. It isn't perfect and was never going to be. If I torque the chuck harder it throws things off. I have a piece of turned 316 stainless that shows 0.003" no matter what I do. Lol. Screw that thing! 

I am bedding in my collet chuck as I type this. No reason not to. Once I dial it in again it should be pretty good for most things unless I need absolutely perfect on a second op. I'll pop it loose tomorrow at noon and then dial it in.


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