Fabricating a backing plate for a chuck

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AllenH59
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Fabricating a backing plate for a chuck

Post by AllenH59 » Wed Nov 16, 2011 1:02 am

Gentlemen:
My lathe has a threaded spindle, of an odd size, and I want to make a backing plate for a 12 inch chuck, I want to fabricate one from a piece of shaft and a peice of plate, I would probably use 1" plate for the backing plate, and a scrap of something close to 4 inch shaft for the threaded hub. The spindle is 63mm x 6 tpi.. I could taper thread the plate onto the hub, or weld it on. Yes I am doing this because I am cheap. I would also rather make one than buy one. I would like to see a discussion on this.

Patio
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Re: Fabricating a backing plate for a chuck

Post by Patio » Wed Nov 16, 2011 1:42 am

Hi Allen
I am one of the new guys here, but this is what understand.
You should make a copy of your threaded spindle, including the distance to the shoulder, for a test plug. Once you have that, as you make the backing plate, you can use the plug to test the fit. That way you don't have to remove the backing plate from the lathe until it is done.
Hope that helps.
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swatson144
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Re: Fabricating a backing plate for a chuck

Post by swatson144 » Wed Nov 16, 2011 5:56 am

Yep what Patio says. I'd even go one farther and recommend making the female part as a spindle protector. You'll likely need it later and it's good practice.

I'm not sure I'd want a steel back plate especially a 2 piece. I've seen people make them from cast iron barbell weights.

Steve

stevec
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Re: Fabricating a backing plate for a chuck

Post by stevec » Wed Nov 16, 2011 7:41 am

I dunno about a 12" chuck on a threaded spindle nose. You'd best lock out the reverse and brake (if you have one).
That being said, if you can weld a 4"D to a 1" plate properly, that would be my choice.
Oh, and Pat's suggestion of making a duplicate of the spindle is well worth the effort.

AllenH59
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Re: Fabricating a backing plate for a chuck

Post by AllenH59 » Fri Nov 18, 2011 9:45 pm

Gentlemen,\
Thanks for the advice, actually, I made a copy of the spindle nose long ago as a project. When I was learning to thread. I made and extention for the nose out of a good sized peice of shaft so I could machine stuff on both sides of a face plate. I never used it, but I could make a pulley and true up both sides with out taking it off the face plate. I learned to machine on this lathe, and have got by without reverse or the brake, both of which are there but I never use. I am not concerned now about the internal threading, or the welding on of a backing plate.

stevec
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Re: Fabricating a backing plate for a chuck

Post by stevec » Sat Nov 19, 2011 7:48 am

Just out of curiosity, what kind of lathe do you have with an odd sized spindle and can swing a 12 inch chuck? Any pics? :wink: :wink:

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Charlie W.
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Re: Fabricating a backing plate for a chuck

Post by Charlie W. » Sat Nov 19, 2011 1:24 pm

I use to have a Jet lathe with a 60mm x 8 thread on the spindle. I made a backing plate from a barbell weight. It worked great. I made a welded backing plate for a Sheldon I use to have and it had issues with chatter. It seemed to me to be more springy and less ridgid than the cast iron plate.

The plate was not quite thick enough at the hub to fully cover the spindle sp I cut a counterbore in the weight and pressed an extension into it to make up for the short comming.

Image

I bought this collet chuck which had a 2-1/4 x 8tpi in it. I bored it out to the 60mm x 8 size I needed.

Image

Having made backing plates these two ways, I recomend 1: finding a plate with a slightly undersize thread and boring it out to your size or 2: just buying a backing plate blank to start with. The weight worked great but finding one the correct size is not that simple.


Charlie
Last edited by Charlie W. on Sat Nov 19, 2011 8:10 pm, edited 1 time in total.

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swatson144
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Re: Fabricating a backing plate for a chuck

Post by swatson144 » Sat Nov 19, 2011 5:14 pm

Charlie W. wrote:I use to have a Jet lathe with a 60mm x 8 thread on the spindle. I made a backing plate from a barbell weight. It worked great. I made a welded backing plate for a Sheldon I use to have and it had issues with chatter. It seemed to me to be more springy and less ridgid than the cast iron plate.
That would be the main reason I wouldn't want to use a steel plate. I would expect harmonics. I could be wrong but I have seen steel fishing poles, springs etc but never cast iron.
Steve

AllenH59
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Re: Fabricating a backing plate for a chuck

Post by AllenH59 » Sun Nov 20, 2011 3:42 am

I have a Hi Tech SG 2 Lathe, from chaitanya machine works in Rajkot India. I imported it myself in about 2000, it cost $2900 fob Mumbai, with a cooling system, a taper attachment, a 8" 4 jaw and a 6" 3 jaw. I still use the live center it came with. It takes a #5 MT in the headstock and a #3 in the tail stock. It will cut all the metric and standard threads. It will swing 16"x48" over the bed between centers, and 10" diameter over the cross slide, and 23" diameter in the gap. They reccomended bigger chucks, but I could not imagine why I would want them, and true enough, I could get by just fine without them for the work I will do. I would like a bigger 4 jaw as it has a bigger hole through it, but that is all, I do not expect to be swinging anything bigger than 8" diameter. I bought this to learn to machine on, and I am quite happy with it ten years later. It has an adjustable tailstock, and I always have to shift it if I want to do very accurate work. I bought a lathe this big as I thought that some day I might want to drill rifle barrels, but I am not there yet, and am fairly sure this is not the machine for it if I wanted to. It does have the odd size spindle, but I did not know enough at the time I bought it to look for one with a lock on chuck system. this is a link for a newer model, with a shorter bed. http://www.hitechlathe.com/Trainer_100.html
(they did not sell them as trainers when I bought mine. )
While this is not a production model by any stretch of the imagination, it will do almost what ever you want a lathe to do if you take a little time. It will take a 3/4" tool in the tool post it came with, and I bought a QCTP for it.
There are many more distributors of lower priced lathes now than there were then, but have a look at their website, they build some interesting machinery.
Attachments
Lathe.JPG
My lathe in my messy shop. that tool box holder I built on top has a large edge to keep anything from rolling into the work.

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