Getting material to run true in metal lathe.

Getting material to run true in metal lathe.

Postby Wheels » Thu Feb 09, 2012 4:27 pm

On a couple of occasions when I chuck up a rod on my metal lathe....getting it to run true is tricky. So far all I've messed with is aluminum. I have noticed that I can get it to run true by tapping the side near the end while it turns. Probably not the most elegent solution but it worked.

Am I not tightening the chuck enough? Or what other process do I need to follow?
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Re: Getting material to run true in metal lathe.

Postby Richard-TX » Fri Feb 10, 2012 9:49 am

I assume you mean with a 3 jaw chuck.

I find that rotating the workpiece in the chuck while tightening helps.

Maybe it is your technique? Put a video up on you tube and post the link here.

A 6 jaw chuck works wonders. I can pretty much just toss a piece in the jaws and it runs true. The exception is pieces that engage a fraction of the depth of the jaws.

There is a maximum length that can turned without help from a center in the tailstock.

If you really need something to run really true, the adjust-true chucks are the only way to fly.
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Re: Getting material to run true in metal lathe.

Postby Wheels » Fri Feb 10, 2012 11:06 am

There was about 6" of a 5/8" dia bar sticking our of a 3 jaw chuck. I gather for your response that it's all in the chuck and chucking which is just common sense I guess.

So for now...will take more time chucking. A marginal chuck is the last thing I want to fight with and I do want a set-true but can't justify the $$$ for that right now.

Thanks

W
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Re: Getting material to run true in metal lathe.

Postby Richard-TX » Sun Feb 12, 2012 12:52 pm

It is painful buying a new chuck. There just isn't any way around it. On the plus side, the chuck can be used on almost any lathe provided that the proper back plate is purchased. I bought my 6 jaw chuck from Shars.

I think your lathe has a threaded spindle which could mean that a backing plate might have to be machined.

I still occasionally use my 3 jaw and 4 jaw chucks but that is about 3 times a year. The 6 jaw chuck is used well over 95% of the time.
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