PDA

View Full Version : Centering Inaccurate 4 jaw chuck



azzrock
20th Dec 2013, 05:13 AM
any other tips out there on center height?
i use a height gauge.

DoctorWu
19th Feb 2015, 12:14 PM
I have 2 100mm chucks, one a Burnerd 3 jaw and the other a 4 jaw self-centering Tos. I use these on a Myford Super 7 but the Burnerd has never centered accurately. The Tos was accurate when I bought it 15 years ago but now not after some misuse by me when I hammered on an 80mm piece of pipe to prepare for a welding test piece. Bugger!
Does anyone know if there is an 'easy' way to get them on center again.

BobL
19th Feb 2015, 02:21 PM
I have 2 100mm chucks, one a Burnerd 3 jaw and the other a 4 jaw self-centering Tos. I use these on a Myford Super 7 but the Burnerd has never centered accurately. The Tos was accurate when I bought it 15 years ago but now not after some misuse by me when I hammered on an 80mm piece of pipe to prepare for a welding test piece. Bugger!
Does anyone know if there is an 'easy' way to get them on center again.

How far out is it?

DoctorWu
19th Feb 2015, 03:29 PM
How far out is it?

I've never measured them but visible and the Burnerd is worse. I'll get around to doing a measurement. Fortunately I have a collet chuck for any accurate work.

DoctorWu
19th Feb 2015, 04:50 PM
0.17mm measured at the jaws.

casjon
19th Feb 2015, 07:57 PM
There are quite a few videos on the subject, here's a couple:

https://www.youtube.com/watch?v=nALN0qGZbgY
https://www.youtube.com/watch?v=-yWsjeY6nJU

I used a cheap electric Dremel type grinder clamped in the tool post. Make sure all is set up correctly before starting and use the grinder sparingly. Each grind results in the gripping faces of the jaws becoming wider so increasing the diameter of the stock able to be held in the chuck.

pipeclay
19th Feb 2015, 08:08 PM
Short answer to your question is NO.

DoctorWu
20th Feb 2015, 08:59 AM
There are quite a few videos on the subject, here's a couple:

https://www.youtube.com/watch?v=nALN0qGZbgY
https://www.youtube.com/watch?v=-yWsjeY6nJU

I used a cheap electric Dremel type grinder clamped in the tool post. Make sure all is set up correctly before starting and use the grinder sparingly. Each grind results in the gripping faces of the jaws becoming wider so increasing the diameter of the stock able to be held in the chuck.

Thanks and I'm glad I saw that bit about locking the jaws in tight as I had been thinking about grinding and missing that aspect might have really brought me undone.

casjon
20th Feb 2015, 06:29 PM
Another method I've seen is mounting a square file in the tool post and running the carriage back and forth. I don't think there would be much chance of removing too much metal that way, but if you're elderly, you might never see the job finished.

DoctorWu
21st Feb 2015, 03:54 PM
Another method I've seen is mounting a square file in the tool post and running the carriage back and forth. I don't think there would be much chance of removing too much metal that way, but if you're elderly, you might never see the job finished.

On hardened jaws? I don't think so.

BaronJ
21st Feb 2015, 11:07 PM
On hardened jaws? I don't think so.

Might get away with a diamond file.

DoctorWu
29th Jun 2015, 07:12 PM
Ok, I finally got around to working on the Tos 4 jaw. After some careful honing with a 600 grade diamond stone I managed to get it more accurate than it was when new.

DoctorWu
1st Jul 2015, 10:07 AM
I have 2 100mm chucks, one a Burnerd 3 jaw and the other a 4 jaw self-centering Tos. I use these on a Myford Super 7 but the Burnerd has never centered accurately. The Tos was accurate when I bought it 15 years ago but now not after some misuse by me when I hammered on an 80mm piece of pipe to prepare for a welding test piece. Bugger!
Does anyone know if there is an 'easy' way to get them on center again.

I did a post earlier but didn't include this quote. Fixed the Tos by carefully honing the jaws with a 600 grade diamond stone. Better than new now.