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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
Find out how it is seating on the spindle before you do anything.
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?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
Did that and it was within .0005 easily.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
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
What did the company rep say about this problem?
Did you get the 4 jaw also ..How does it run?
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
It is new. Taiwan eisen. I’ll learn about cam locks.
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
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
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.
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