D1-4 Spindle & Chuck Measurement and Setup

Thanks for the kind words...

It surprises me how far off some of the back plates are and it's really annoying when they don't fit well (or if they fit at all).

Just remember, proceed cautiously as once you take metal off, it's real hard getting it back on. And if you make a boo-boo, you'll probably still end-up with a better fitting chuck than what you started with. At least it will go on and sit flush then, you can tap it into center before cranking the lugs tight. In the worst case, you'll need to buy a new back plate. It's all part and parcel of learning this stuff.

Good luck with your new equipment!

Ray

EDIT: You might want to look at the recent tread about fitting a chuck to a backplate. There's a few more details to ponder.
http://www.hobby-machinist.com/showthread.php/13332-Fitting-new-chuck-to-backplate-for-beginners

MikeWi said:
I've greatly enjoyed reading this thread Ray, and as I'm receiving a new lathe at the end of the month, it helps me to check up on things before it gets used. I'll need some practice before being brave enough to do any adjustments, but hopefully it won't be too far off out of the box. :)

I'm learning an amazing amount on this site. This is better than any book, although I always collect all sorts of books on my hobbies. :)
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This is an excellent write up. Our lathes are very similar except mines older. I'm going to be making a faceplate for it sometime in the near future This tutorial will help me to make it just right.
 
One thing to mention... You don't absolutely need a surface grinder to flatten the side of the backplate that contacts the spindle. If you don't have a SG, just make a witness mark (with ink at first) on the side of the spindle and backplate and always attach it in that orientation. Next, mount the plate and surface the side that contacts the chuck. -Then follow the rest of the procedure. Doing it this way will mask any potential mis-alignment between the spindle and backplate.

Ray


xalky said:
This is an excellent write up. Our lathes are very similar except mines older. I'm going to be making a faceplate for it sometime in the near future This tutorial will help me to make it just right.
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No SG here. I can get the faceplate roughed in on the mill and then finish cut it on the lathe. When I did my Chinese chuck and faceplate on the Southbend 9 a was able do get it dialed in by changing the chuck orientation to the backplate, i had 3 positions by rotating it 120 degrees. I was able to get real close that way. and then just snugging up the backplate to chuck bolts a little and tapping the chuck with a soft face hammer, i was able to get it within .001 in all directions, checked with a piece of drill rod chucked up in the jaws, and indicating to the drill rod. I was pretty proud of myself. :))
 
Just want to mention that there's no mysteries to be solved here. Fitting a chuck is a basic and simple operation. Here's my general philosophy and procedure.


  1. The interface between the spindle and backplate must be flat and repeatable.
  2. The chuck should be fairly well balanced. The backplate should be fairly well balanced. The overall combination of the two should be fairly well balanced. It's hard to achieve perfect dynamic balance at all speeds thus, static balance is usually the best you can do.
  3. The interface between the backplate and chuck should be trued-up such that the face of the chuck shows no runout. If there is runout in the face, you start by facing the backplate. After adjusting that, if the face of the chuck will not read with zero runout then, you need to adjust the back of the chuck.
  4. I am not a big fan of making a shoulder on the backplate that tightly fits the chuck. The chuck should be centered on the backplate such that a rod placed in a collet chuck or 3 jaw scroll chuck shows little/no runout when reading about 1" protruding from the jaws or collet. A 4 jaw chuck should be centered on the backplate by reading off the side body of the chuck. If you make a tightly fitting shoulder, you won't be able to make these adjustments and you're at the mercy of how well centered the chuck cavity is when it was machined.
  5. The jaws of any chuck should be adjusted such that there is minimal runout (up to 4 thou) when reading with a DI off a rod about 6" from the face of the jaws. This is adjusted by filing/grinding the gripping teeth of the jaws. If you have a chuck with sloppy fitting jaws within their journals that will not repeat and hold within 4 thou, it's likely time for a new chuck.

This is how I adjust all my chucks and if I need to spin with higher levels of precision, I use a dog and spin between centers.

Ray
 
This post is great. I´ll try to fix my lousy D1-4 chucks (the 3J is off by 4 thou and the 4j is off by 15-20 thou!). And they are not repeatable at all.

It may be a lot off topic, but I´ve readed in "Home Workshop Hints and Tips" about using a accurately machined between centers piece of round stock, mount it between centers, tighten the chuck´s own jaws in it´s middle and then turn (face) the chuck back plate. Has someone tried it? It seemed pretty ingenious to me. This topic of the book was called "curing the incurable chuck".
 
This may be a little more information then what members might be looking for but I happen to have the manufacturing dimensions and tolerances for lathe chucks and spindle noses that I purchased from ASME (American Society of Mechanical Engineers). Its a copyrighted doc. # USAS B5.9 - 1967 (45 pages) . It covers spindle nose Types A, B, D, and L . I will share info from it with those who need it.
 
Hello Bruce,
I bumped into this old thread because of your recent reply.
The OP wrote (#1) "There should be no light coming between backplate and spindle face."
I'm interpreting that sentence to mean that both the planar faces and the conical surface are supposed (designed, intended) to be in intimate contact simultaneously.
I've read that opinion before but never seen it in a controlling specification.
I'm wondering if B5.9 makes any statements that would support the OP's statement?
Can you shed any light?
 
Hi extropic

It will be a few days before I have the time to dig through the specs but I will get back to you with what I find out.
 
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