4-Jaw Chuck - Winding screws?

[Ross]

Hello everyone,

I'm currently (attempting) to make a crankshaft from solid on my lathe..
Was about to start the fixture for the final op today but my Chinese 4-Jaw Chuck let me down, one of the threads has peeled off of the winding screw for one of the jaws.

I have tracked down the manufacturer in china but am unable to find anything in the way of spares although I have contacted them to see if they can help. and I don't really want to be forking out for a new chuck just for the sake of a screw. Anyone got any ideas? I could see about getting one made if I knew info about the thread etc.. 

The Manufacturer; http://www.c-chuck-en.com/index.htm

The offender;

[sparky961]

Do you have any other chucks or ways to hold material?  3-jaw, centres with dog, etc?  How about thread pitch gauge, or the ability to carefully measure things with calipers?  Can you grind a HSS tool blank to match a shape?

With the above and a few skills, this isn't too difficult a thing to make yourself.  Even if it isn't perfect you can get by until you develop more skills to make a better one.  It's a great learning project with real purpose.  Make a few spares while you're set up.

Alternatively if threading is not your cup of tea, perhaps you can find some threaded rod with the correct thread type and pitch and modify it to suit.  The recessed square typical of most chucks isn't necessary.  You could do it a number of ways that are easier to make.

Finally, is there someone else that would like a moderately challenging project near you?

[sparky961]

By your other post it appears you work in a shop equipped with at least one 5-axis mill, so likely more machines where that came from.  You can probably find an appropriate CNC machine to make it happen.

[Ross]

Yeah I have a 3 jaw, and I've thought about making one although the thread does put me off somewhat.. also it would need a square recess for the chuck key..

Unfortunately everything at work is all larger diameter stuff and I'd never get a free machine as we are always busy

[sparky961]

There is actually a way to drill a square hole.  A quick YouTube search should yield plenty.  There are other ways too if you insist on having a square hole.  But as I said before there are other ways it could be designed that are easier to make in a hobby shop.  A slot, male square, or male hex come to mind initially.  Replace all the pins with your own creations and make a chuck key to suit.  Pick the right steel and they'll far exceed the quality of the original Chinese mystery alloy.

Kinda makes me think too, how the heck hard were you reefing on that thing?  I've never seen one of those stripped.

I'll stand by my advice to make it yourself.  Its very empowering to know that you can make your own replacement parts rather than find and pay for a drop-in replacement.

But if you lack the desire, then start calling around to places that sell similar equipment and be prepared to pay whatever they ask.

[Ross]

Of course, I'll have a good go at making one as a last resort. I'm not against making one but the end goal in my eyes is a finished crank and other assorted jobs, this gets in the way slightly and I am looking at a slightly quicker fix..

I wasn't giving it a lot of hammer, just using the standard chuck key this hasn't happened all in one go, originally only a small part of the thread went. I should've started looking for a replacement then in hindsight.. I had to keep dressing the thread as it came off bit by bit.

[chipenter]

Moding a hex grub screw may make a good donner , my 4 jaw has had hex heads brazed in at some part of it's life .

[Ross]

I Decided To go down the route of getting a new chuck in the end.. this one has much heavier duty winding screws.

Now back to business..