chucks

Hi all, I have just taken the jaws out of my 4 jaw self centering chuck without marking no. 1 jaw. How do i tell which one it is?

Terry.

Is there nothing stamped in the slot down the side of the jaws?

Jo

Lay them on the bench teeth up.

The one with the tooth closest to the middle of the chuck, inside of the jaw, is no 1 jaw. Next closest is 2 and so on.

Simples.

regards David

Hi, The jaws themselves are numbered, but which is no 1 slot?

Terry.

Terry,

In theory*, it shouldn't matter. What is important is that you push the number 1 jaw into a slot and get the start of the scroll to engager the first tooth. Then, before the scroll front reaches the next slot clockwise, push the second jaw into that slot and rotate the scroll just far enough to grab that jaw; proceed similarly with 3 and 4. After engaging each jaw, give it a good tug to make sure it has actually been engaged; if not, back off the scroll and try again. You will know if you have done it correctly as if you haven't, the jaws wont all meet in the exact centre.

One some chucks I think the No 1 slot may be marked; if so, use it and then go round clockwise. It may also be interesting with an unmarked body to use each slot in turn as No 1 and see which gived the lowest runout. Then, obviously, mark that as No 1.

David

*Obviously, there may be cases of poorly-made chucks where this is not true.

Edited By David Littlewood on 09/08/2012 16:46:49

Is the no 1 slot not the first slot anticlockwise after the makers stamp

...or is it clockwise...

Shouldn't that be anticlockwise (when seen from the front?

Russell.

My 4" 3-jaw (screws on to Myford spindle nose) is a Burnerd and front of chuck is stamped 1,2,3 next to each slot and the matching jaws also stamped on one side. I also have a 6" 4-jaw which is similarly marked.

John

On my chuck I did not know to check, so I have standardised on the slot OPPOSITE the maker's mark. Works well for me, I once had a bar showing less than 0.0005" out at 4" from the jaws.

Neil

I am going down to my workshop now. I will look at all your ideas and let you know.

Terry.

All is now clear, I e-mailed RGD Engineering from whom I purchased the HBM 4 jaw chuck. I was told there was a number 1 stamped at the rear of the slot on the main chuck body. I had already looked for some thing like this, but this time i used a magnifying glass. Low and behold there was a very faint 1.On inserting the jaws and testing, all seems to be back to normal. Number 1 jaw on this chuck is to the right of the lathe size engraved on the front face. Thanks for all your sugestions.

Terry.

Russell,

Quite right, my mistake, I apologise for the confusion. Shows the danger of replying to these things sitting at a computer and relying on memory, instead of actually going to the workshop to check. I hope the mistake would have become obvious to anyone who watched the scroll going round.

David

Edited By David Littlewood on 11/08/2012 12:34:27