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Best way to true up 3 jaw?

Mram10

Cast Iron
Joined
Dec 17, 2017
I have a new eisen 1236gh lathe and want my 3 jaw to run more true. Came up with 2 options:
1. True chuck jaws
2. True back side of chuck
It’s .007 off at 1” from chuck now. Thanks guys
 
I have a new eisen 1236gh lathe and want my 3 jaw to run more true. Came up with 2 options:
1. True chuck jaws
2. True back side of chuck
It’s .007 off at 1” from chuck now. Thanks guys

BEST way to "true up" any scroll chuck is to replace it with a 4-J independent. Level of accuracy is then up to you, uber-precise - near-zero TIR when you need that, not so much when you do not.

The "free" bonuses vs a 3-J include right around double the gripping power and ability to work odd-shaped parts.

End of problem. Forever.
 
Find out how it is seating on the spindle before you do anything.

Maker (Taiwan) sez that model uses a D1-4 mount. Dykem and such would be needed. What to look for and what to DO about that in the D1-3 camp, Monarch forum for example.

Also not likely to be the source of the problem if "new" is even close to accurate.

Imperfections in the chuck's scroll, rather.
 
New chuck on a new lathe should run better than .007 an inch out IMHO..

If the chuck is on then I would put the test piece back in and check to see if it is axial run out or wobble and mark the part error..

You might blue-up a known straight round part and snug tighten then push or turn a bit in the chuck to see if there is a jaw nick or bug..

Then I would indicate the chuck OD , and the chuck front or back face to see if the whole chuck runs like the test piece and mark the chuck error.. If the chuck body runs good I might take out the jaws to inspect how clean the chuck and if there are any bugs on jaws or scroll. Then I would use wood a 2x2 and give a light pry-up looking for a sudden movement that might suggest the spindle take-up was tight or lose.
Then take off the chuck and indicate the spindle nose for face and hub.
You might check that draw pins are solid and all the same and all pulling the chuck tight.
http://www.tools-n-gizmos.com/specs/Lathe_Spindle_Mount.html

*You should be able to determine the exact reason before you make any changes..if the lathe is good you might send back the chuck.

Be sure the jaws are correctly numbered.. and that you know how to replace them before you pull jaws.
It is possible this lathe outfit has a service contract with a local machine repair source.
 
As described, make sure the chuck scroll is clean and the spindle nose register and then the chuck body are running true. Take the chuck haves apart to verify there is no crud/casting sand.

Single or two piece jaws? Jaws should have been ground installed in the chuck when it was manufactured. If two piece, they should be numbered top and bottom. Make sure they match. Even if they match, swap top jaws around and test for runout in each iteration. I usually use a 3/4" endmill shank in the chuck because it should be ground pretty true. I found the second hand Bison chuck I have went from 4-5 thou runout to just over .001" when I got the two piece jaws matched up properly.

If you can't get it any better then google "grinding chuck jaws" and you should find several methods
 
I have a new eisen 1236gh lathe and want my 3 jaw to run more true. Came up with 2 options:
1. True chuck jaws
2. True back side of chuck
It’s .007 off at 1” from chuck now. Thanks guys
Don't say if the chuck is new or not but still need to see what runs true and what does not. I would start at the chuck and indicate the OD and face near the edge to see if it runs true on the lathe. If it does it means the chuck jaws or scroll is the culprit, if not it means the mounting is in error. Mounting error could be at the spindle or the face of the adapter if it has one. Big question is do you know how to use the cam locks if that is what the spindle has as someone suggested?
If it is an old worn out chuck then it might be wise to toss it in the trash, scrolls get sprung and busted from abuse, the bodies can get sprung and the jaws can be bell mouthed. You're the one that has to evaluate the thing and decide what is appropriate under the circumstances.
Dan
 
Actually, I'd start without the chuck, measuring the runout of the internal taper and register surfaces of the spindle. Once that has been cleared, I'd move on to the chuck.

Paolo
 
Seating was fine. I decided to put a chunk of 3” aluminum in my 4 jaw and turned it. Made it true then tightened the 3 jaw onto it and took off the rear holder bolt thingies. Took .002 off the back and put it back together. I tested the runout again at 8”from the jaws and it was .0025. Nice improvement.
 
Actually, I'd start without the chuck, measuring the runout of the internal taper and register surfaces of the spindle. Once that has been cleared, I'd move on to the chuck.

Paolo
Did that and it was within .0005 easily.
 
Don't say if the chuck is new or not but still need to see what runs true and what does not. I would start at the chuck and indicate the OD and face near the edge to see if it runs true on the lathe. If it does it means the chuck jaws or scroll is the culprit, if not it means the mounting is in error. Mounting error could be at the spindle or the face of the adapter if it has one. Big question is do you know how to use the cam locks if that is what the spindle has as someone suggested?
If it is an old worn out chuck then it might be wise to toss it in the trash, scrolls get sprung and busted from abuse, the bodies can get sprung and the jaws can be bell mouthed. You're the one that has to evaluate the thing and decide what is appropriate under the circumstances.
Dan

It is new. Taiwan eisen. I’ll learn about cam locks.
 
As described, make sure the chuck scroll is clean and the spindle nose register and then the chuck body are running true. Take the chuck haves apart to verify there is no crud/casting sand.

Single or two piece jaws? Jaws should have been ground installed in the chuck when it was manufactured. If two piece, they should be numbered top and bottom. Make sure they match. Even if they match, swap top jaws around and test for runout in each iteration. I usually use a 3/4" endmill shank in the chuck because it should be ground pretty true. I found the second hand Bison chuck I have went from 4-5 thou runout to just over .001" when I got the two piece jaws matched up properly.

If you can't get it any better then google "grinding chuck jaws" and you should find several methods

Jaws are single piece. Cleaned them up good. I’ll try the chuck in each mounting position and compare. Trying to avoid grinding since I don’t have the correct tools
 
It is new. Taiwan eisen. I’ll learn about cam locks.

Each D1-(X) camlock stud has to be adjusted - at least "in the beginning". The small hex head capscrews that engage a slot on each stud to limit rotation must temporarily be removed for this setting up, put back afterwards.

Each camlock stud is in the right range when the cams in the spindle take up their grip around the 4:30 o'clock position, never before 3 or past 6. It is out of your eyesight, but they rotate slightly as the two cam's surfaces mate. That's why the anchor screws have a slot to allow some movement, but not enough to make a full turn.

Be happy the D1-4 has only 3 such studs, as it is a PITA on D1-6 , etc.

Page two:

A D1 expects to bear on BOTH its short-taper AND the flat face adjacent. Dykem or Stuart's Micrometer may show that they are NOT in such perfect sync.

Even the newest lathe of all can acquire a ding that raises a burr. Those must be found and gently stoned off before anything can get into its proper place.

Your really want to make this test first - with the pins removed. And you need more than one backplate.

How best to address any error found depends on whether it is one odd backplate and a good spindle, error in spindle finish, or some of each.

Do not rush into trying to correct that one.

Record and share findings, confer with PM, rather. It is not a new challenge. It is best to double and triple check - or more - before risking a screwup.

The good news is that with reasonable care, you do this very seldom.

A D1- in good order lets you pull a chuck or nose-mount collet system, even with work clamped in it, swap in another, and another, come back to the first one and find the workpiece left in it is near-as-dammit right back on the same center, TIR-wise.

That's a very, very, nice feature, and not readily given-up, once you get used to it.
 
snip

A D1 expects to bear on BOTH its short-taper AND the flat face adjacent. Dykem or Stuart's Micrometer may show that they are NOT in such perfect sync.

snip


Pure unadulterated :icon_bs:

I've read the equivalent of that statement many times, on this forum and others. It is a false statement.

It's so unreasonable that I'm surprised that it floats so commonly along. But, that's a different subject.

To find the facts I purchased a copy of the controlling standard, USAS B9.5-2014.


USAS B5.9-2014 Cover Only, I Own Hard Copy.jpg


Per the Standard: (All dimensions are INCHES)

"3.1 Master gages of the ring and plug type are recommended for inspecting the taper pilots of Types A, B and D spindle noses and the taper holes in the mating face plates and chucks."

There are tables specifying the dimensions and tolerances for the master gages. The tolerance for each taper (on a master gage) is ±.0001 AND the ring and plug gages "should be good Prussian Blue fit on mating surfaces" (tapers and faces). This means that the master gages, plug and ring, are matched as a set however the absolute size of that set still has a tolerance of ±.0001 on the taper relative to it's face. My point: even the master gages are not required to be of a perfect size. Everything has a tolerance.

In the tables describing the spindle tapers the following Gage Clearances are specified "FROM FACE OF SPINDLE TO FACE OF MASTER GAGE".
D1-3 = .001/.000
D1-4 = .002/.000
D1-5 thru D1-11 = .002/.0008
D1-15 & D1-20 = .004/.002

In the tables describing the chuck and face plate tapers the following Gage Clearances are specified "FROM FACE OF CHUCK TO FACE OF MASTER GAGE".
D1-3 = .002/.000
D1-4 = .002/.000
D1-5 thru D1-11 = .002/.000
D1-15 & D1-20 = .004/.000

Conclusions:
The following numbers are further subject to the effect of the actual size of the master gage set (or uncertainty of other metrology) used to qualify the spindle and chuck/face plate.
There is a DESIGNED-IN CLEARANCE between the faces of D1 spindles and chucks.
D1-3 = .003/.000 Face to Face Clearance
D1-4 = .004/.000 Face to Face Clearance
D1-5 thru D1-11 = .004/.0008 Face to Face Clearance
D1-15 & D1-20 = .008/.002 Face to Face Clearance
 
Pure unadulterated :icon_bs:

I've read the equivalent of that statement many times, on this forum and others. It is a false statement.

It's so unreasonable that I'm surprised that it floats so commonly along. But, that's a different subject.

To find the facts I purchased a copy of the controlling standard, USAS B9.5-2014.


View attachment 218595


Per the Standard: (All dimensions are INCHES)

"3.1 Master gages of the ring and plug type are recommended for inspecting the taper pilots of Types A, B and D spindle noses and the taper holes in the mating face plates and chucks."

There are tables specifying the dimensions and tolerances for the master gages. The tolerance for each taper (on a master gage) is ±.0001 AND the ring and plug gages "should be good Prussian Blue fit on mating surfaces" (tapers and faces). This means that the master gages, plug and ring, are matched as a set however the absolute size of that set still has a tolerance of ±.0001 on the taper relative to it's face. My point: even the master gages are not required to be of a perfect size. Everything has a tolerance.

In the tables describing the spindle tapers the following Gage Clearances are specified "FROM FACE OF SPINDLE TO FACE OF MASTER GAGE".
D1-3 = .001/.000
D1-4 = .002/.000

D1-5 thru D1-11 = .002/.0008
D1-15 & D1-20 = .004/.002

In the tables describing the chuck and face plate tapers the following Gage Clearances are specified "FROM FACE OF CHUCK TO FACE OF MASTER GAGE".
D1-3 = .002/.000
D1-4 = .002/.000
D1-5 thru D1-11 = .002/.000
D1-15 & D1-20 = .004/.000

Conclusions:
The following numbers are further subject to the effect of the actual size of the master gage set (or uncertainty of other metrology) used to qualify the spindle and chuck/face plate.
There is a DESIGNED-IN CLEARANCE between the faces of D1 spindles and chucks.
D1-3 = .003/.000 Face to Face Clearance
D1-4 = .004/.000 Face to Face Clearance
D1-5 thru D1-11 = .004/.0008 Face to Face Clearance
D1-15 & D1-20 = .008/.002 Face to Face Clearance

Fuck the clerks, bean-counters, and their sloppy penny-saver production clearances of ancient times. Great Depression era was it? 10EE's had D1 around 1936/37 whilst in development stage, shipped production versions 1939 onward.

We who use the damned things in the here and now like 'em tight and STABLE!

D1-3 is borderline fragile otherwise vs a face-bolted A2, an L-series, or even the oddball Cazeneuve proprietary.

Hendey crew noticed that when they put the stouter D1-4 on a mere NINE inch swing Tool & Gage lathe. They were not alone. Wish Monarch had done the same for all the torque a Dee Cee 10EE has on-tap.

His modest but honest Eisen will be far the better for it if that net .004"/.000" "clearance" is at least cut in half.

Or had you noticed NOT that very nearly the exact same clearance for a D1-4 is called for clear up to D1-11? And that.. is a rather larger.. animal. Do the trig?
 
There is a DESIGNED-IN CLEARANCE between the faces of D1 spindles and chucks.
D1-3 = .003/.000 Face to Face Clearance
D1-4 = .004/.000 Face to Face Clearance
D1-5 thru D1-11 = .004/.0008 Face to Face Clearance
D1-15 & D1-20 = .008/.002 Face to Face Clearance

NO, there isn't. The clearances you quote are there to ensure that when a chuck is pulled back with the pins it touches both places.
 
NO, there isn't. The clearances you quote are there to ensure that when a chuck is pulled back with the pins it touches both places.

+1 It is meant to ride up that short taper just enough to be in functional interference fit, be stopped firmly at "just right", and that is what we want to see reflected on the flat.

BTW: If anyone thinks those pins have the strength of their major diameter? I invite you to section one right across the cam cutout's thinnest point.

About the same area as a MUCH smaller full-round no-notch capscrew, but in a far less optimal shape, stress-wise. Scary small, even.

Cazeneuve's coned forcing screw alternative may be dumb-like-a-fox, after all. Especially as they ALSO have a face-bolting option, same spindle, for heavier loading yet.
 
NO, there isn't. The clearances you quote are there to ensure that when a chuck is pulled back with the pins it touches both places.

^^^ :icon_bs: ^^^

You're certainly free to imagine what ever circumstances you like.

I wonder what force would be required to sink a steel chuck even .001 further after being fully seated on a D1-4?

I'm out of the business now, so don't have easy access to the resources needed to perform the test but, experience would lead me to guess that it's much more than the cam locks commonly apply.
 








 
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