Upgrading 3 jaw chuck?

[vladdy]

I replaced on old Logan power chuck on a #3 Gisholt about? a year ago with a Bison 3 jaw, and it has worked out well for it's intended purposes..
I also had to get an adapter plate [they call it machined ..:0] to fit the lathe nose to the Bison's plain back..
Took maybe two relatively slow evenings to get it done, but probably took maybe close to 1 1/2" off the front of the adapter to get it to where I wanted it...I felt that the closer the chuck bolted onto the nose the more steady and accurate it would be..
The old critter isn't used much, but it's a little more versatile with a scroll chuck now...

enjoy..

[scbvideoboy]

Well the latest saga, is I took the face plate and cut a recessed slot on that so the bison chuck would fit, as the shoulder step on the face plate is a larger diameter than the bison chuck, and fit that on it. Real nice fit, I felt and see no play. Drilled the mounting holes and tested it, after all the work, frustration, 400 dollars for the new chuck I am seeing no vast improvement on the trueness.

So either I am going to have a professional make me an adapter or live with it.

Wonder how close the face plate is, as it's meant for the four jaw...

I am off work this week and one of my goals was to finish the chuck and make a couple of parts.

And now the Mill motor is buzzing and popping the breakers (even after I rewired with better wire, connectors etc...way back earlier this year) These motors do not like short cycles. Like when using the drill press.

I'll try to make a part, and see how it goes before any more changes. I went to advanced auto parts to get a V belt (240 size)

I think if I sell the house the machine will be a freebe...

DH

[handlewanker]

Hi Dave, here's my two pennoth worth, usually when fitting three jaw scroll chucks it is best to leave the locating spigot to the back of the chuck a slack fit. That is at least .010" slack on diam. Then nip up the mounting bolts and put a 1 inch diam.test bar, ground steel if possible, in the chuck and leave at least 4 " sticking out.
Now rotate the chuck and using a dial indicator to see if the test bar runs out, tap the chuck body with a soft mallet untill the bar runs true.
This can also work for longitudinal truth, except here you'll have to shim the back plate if it wasn't machined true in the first place. Don't forget to tighten up the mounting bolts when finished. Always remember, a three jaw chuck if it's new will run true at all diams, whereas an old three jaw is good for boat anchors or door stops.
A three jaw scroll chuck is a poor man's collet chuck.
I bought a Chinese made 150mm (6") three jaw chuck, ten years ago for $150 Australian, and found it to be very accurate. I'm a skilled fitter and turner so know how to use the equiptment. The lathe is a Colchester Bantam, 10 " swing, made in the 1930's and has been rebuilt by me from the ground up, including recutting and scraping the bed and saddle bearing surfaces by hand, but that's another story.
If you really must have bar work running true, or previously turned parts remachined to existing diams, then invest in a set of collets, bought on Ebay in sets or a few at a time. Once used you'll wonder how you ever managed without them. They are only suitable for the diams that they are made for, and will NOT suit ANY other diam. You'll probably be working on standard diam bar size anyway.
Hope this helps,
Ian.

[scbvideoboy]

well its been a while, I have been working on my project.

When I was here last I was going throught putting that Bison on.

I have been working with that chuck for a while now, and this has happened:

I took the Bison off the adpater plate to put the 4 jaw on to work with some square pieces, I set the bison on the table.

When I remounted it I noticed a visible wobble in my work.

I had marked the plate and screw holes to put it back where it was but now there is over 12thous run out and I have no idea why.

I dissambled the chuck to clean and inspect it, using dial indicator at jaw 1 with a prescision ground 1" round stock I set the indicator to 0

I rotate slowly by hand and at jaw 2 it's 8thous and jaw 3 it's 12thous and then goes back to 0 by jaw 1

These are 2 piece hard jaws.

using the indicator on the chuck body, I have 1-2 thous runout.

Dave

I'm calling the vendor for info on warranty, low hours on this unit.


***************************edit************************

FIXED it YEAH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Operator error, or more specific: " dipship didn't do the adapter plate right the first time" must have been a planetary alignment luck for the first time I mounted it.

Redid the bolt holes and turned the plate a little more as I finally saw the problem was that the chuck wasn't fully seated into the groove.

Wha la, now I'm getting less than .002 on the runout on the precision ground rod.


YEAH!!!!! I don't have to spend more money!!

Dave