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1 1/2 8tpi 3 and 4 Jaw Threaded Chucks

YotaBota said:
The threads run right up to the face of the backing plate. As Brent said that would mean mounting it and facing off the front, then cutting back the threads far enough for the face to become the register. There is a lot of "meat" to play with but using the face plate is just the way I'm comfortable. Besides,,,,my lathe,,,,my rules,,:)
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Only asking for my own learning.


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I hope you didn't take "my lathe,,,my rules" the wrong way, it was meant to be joking. Asking questions will save you a lot of time, money and skin. It was only 30ish years ago when there were no forums like this to ask for advice and gain knowledge. I do what I can on my own with the net and books but when you're stuck you have to ask somebody and places like this are invaluable.
 
Hey David,

Check out this lathe manual on the vintage machinery site - page 31 - Chuck fitting

http://vintagemachinery.org/pubs/detail.aspx?id=9521

When you asked you question I thought about this as I had read this manual about the Myford 7 for another guy who was looking for one.

Doesn't discuss your issue about machining directly, but it was one of the few times I saw the chuck fitting included in a manual. This lathe manual is actually pretty good - might be why there is a post for one selling 17 grand or something...
 
No
YotaBota said:
I hope you didn't take "my lathe,,,my rules" the wrong way, it was meant to be joking. Asking questions will save you a lot of time, money and skin. It was only 30ish years ago when there were no forums like this to ask for advice and gain knowledge. I do what I can on my own with the net and books but when you're stuck you have to ask somebody and places like this are invaluable.
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I did at first but I re-read it and all good :)
 
I started fitting the backing plate for my 4-jaw tonight and now understand why putting it on backwards won't work.
When I tried backwards it won't run true for exactly the reason @Brent H said; the face won't run up against the flange on the spindle.
What I did instead was to cut the register to fit, then swapped for the 3-jaw and used the 3-jaw to hold onto the register so I could reduce the dept of the nose. Worked like a charm.
 
I am guessing that you cut off the thick washer part from the back of the backing plate. I was thinking you had to bore out the interior of the backing plate. Guess the 0.3" cut should have clued me in. Thanks for the pictures.
 
David - glad that worked for you. What did you end up with for runout?
Hruul - yes, the washer looking piece is what was cut off.
 
YotaBota said:
David - glad that worked for you. What did you end up with for runout?
Hruul - yes, the washer looking piece is what was cut off.
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When I threaded it on backwards it wobbled probably 1/16"+. Enough for me to hit the proverbial brakes in a hurry.
 
Hi David,

How is it running now that you have it machined? I guess that would be the run out on the outside of the 4 jaw as you could adjust the 4 jaw to take any run out out............that is a lot of "outs"
 
I refound a video from a while back by tubalcain on backing plates. At about seven minutes he talks about and shows boring the threads out of the front side of the plate to make the front side the register. It was interesting to watch again and will explain better than I do. It's a two part video so get popcorn.
 
So the 4-jaw is completed.
First let me say that I hate cast iron. What a mess.

I took my time and eased up into the register diameter. Fits like a piston.
Total runout is about 3 thou. Being that it's a 4-jaw that's good for my needs.

One thing I'm not happy about is that that when turning it to final diameter I broke through the counterbores for the mounting bolts.
Shars sells the cuck and backing pate as a pair so I would have expected that the bores would be sized so this wouldn't happen.

I will let Shars know about this as I think it's an issue. I'm not unhappy but I'm not thrilled either.

If I had it to do all over again I'd have bought one of the 4-jaws from HH Roberts.

On the plus side, this was my first attempt at any actual machining and I'm pleased with the result.

IMG_5636.jpg

IMG_5637.jpg

IMG_5638.jpg
 
Nice Job David!

The more you turn the more you will learn! Cast iron is not that much fun but I have been doing quite a bit with it lately....it makes a lot of mess for sure.

I would have thought the back plate would have been slightly relieved at the bolt holes to allow for a skim....interesting.

Great stuff though in getting it done. You may be able to take a thou out of your run out with a few strategic taps but with a 4 jaw you should be a-OK!

Now get machining some off set stuff!!!! WOO Hoo!
 
That chuck is a bit younger then me! It was made on 19th December 1979. And it comes with... a whole 1 year warranty! Made with love for socialism ;)
 
David - Well done, you gotta love it when a plan comes together. If you decide to try Brent's adjustment technique don't forget to lift the arm on the micrometer before the "tap", they have a tendency to be a bit sensitive to sharp taps.
Tom - my warranty has been up for a while as well:D
 
YotaBota said:
David - Well done, you gotta love it when a plan comes together. If you decide to try Brent's adjustment technique don't forget to lift the arm on the micrometer before the "tap", they have a tendency to be a bit sensitive to sharp taps.
Tom - my warranty has been up for a while as well:D
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Thanks, I'm rather pleased with myself to be honest.
I didn't expect that I would be successful on my first machining task. Granted it wasn't that complicated.
 
I took the plunge and ordered the 3 and 4 jaw chuck, same place as @YotaBota . Hard not too, shipping to Calgary was ~65.00 for one, and 75.00 firm for two. My dividing head is 1-1/2" x 8tpi and I've butchered a couple of back plates 'teaching' myself lessons so far. I want to see how fitted backplates work before I teach myself more machine lessons on the 3rd back plate.

Thx for the research @YotaBota, I told the sales guy Ron that he should slide you some profit. I liked the guy, was very up front about how old they were and the fact they needed to be cleaned.
 
I don't think you'll be disappointed, they do need a good cleanup and some working but I'm more than happy with mine.
 
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