centering, another method

[Roy B]

If you take a look at my photo album, under Machining / Gunsmithing, you will see a pretty neat way that I center work in my lathe. I've been doing it this way for years and It works fantastic. Here's the url for the photo album

http://public.fotki.com/Rbertalotto/

 

[Roy B]

A bunch of folks have sent me email for more explaination than the pictures show.
The holes that run through the chuck are slightly larger than the 3/8" bolts I used. It doesn't take much as we are only moving the chuck by a couple thousands. This chuck I'm using is a "True Adjust" It was made to be losened up and the setscrews that run around the perimeter bear on a raised portion of the backing plate. This method works fine, but my method allows you to set a dial indicator and find the EXACT high point and tap it into alignment. You don't need to move two screws to move the material in a third direction. It is so easy it is scary that someone else hasn't thought it up before.
I would suggest if you don't have a True Adjust, with the holes already drilled through the chuck that you could make a back plate that mounts to the lathe, and then make a second backplate that mounts to the chuck. The bolts then could be between these two plates and the same type of adjustment would be possible. Or if you knew how your chuck was designed, you could find an area in the chuck where three holes could be bored without damaging the chuck. But chucks that are designed to be screwed onto a treaded back plate are very inexpensive .
Hope this helps............

 

[Fred T]

Hey Roy
You have a good idea there, the difference between what you are doing and the original set true chucks in very minimal. The only difference being that there is nothing to hold your chuck in place except the pressure of the bolts and the bellville washers. On a set-true you use four screws and move things around like a four jaw but the work is held in a three or six jaw chuck.Then tighten up the attachment bolts that hold the check to the back plate. The adjustment does not bear on the stock that is in the chuck so there is no third dimension. Also bear in mind that if you are doing anything that generates much pressure that you may move the chuck because there is nothing backing it up except the bolt tension. I hope that I didnt muddy the waters to much.
Fred T

 

[Roy B]

Hi Fred,
Understood.....A couple of times I've forgotten to retighten the through bolts, and the chuck didn't move. With a 12 X 36 Jet lathe, I'm not taking 1/4" cuts. Slow and easy is the way I machine so I've never experienced any difficulty.
But it is just so much easier to align things rather than using the set screws that were supplied with the chuck.

 

[Fred T]

HI Roy
I can see that happening! I usually do one of two things, High precision or great big. Either of them have any room for things to be loose. If they are you usually find it the hard way. Good idea for small stuff
Fred T

 

[ashuford]

I noticed that you had a CBX dro. I am thinking
about one for my Bridgeport. What do you think
about the quality compared to a Sony?

 

[Roy B]

Don't know about the Sony as I've never used one. But I can tell you the Shooting Star is great. I have one on my lathe and my milling machine. Been using them for years. Work great with no issues.