Thread: how do you stop the jaws marking work

I cut up soft drink cans - currently Coke cans - the material is surprisingly constant in thickness and use that between the jaws and the work. The stuff is easy to cut with scissors.

Generally I use one piece and wrap right around the work rather than trying to juggle separate pieces. I also leave a small amount hanging out the front of the jaws - it acts as an early warning device if I have a brain-fade and get too close to the chuck with the tool - the flapping noise as the tool hits the turning coke can is a good indication that you are getting too close to the chuck......

I have various sets of vice jaw covers,

Ally, brass, leather covered steel and wood.
Use goes with hardness of material.
To hold steel, use any of the above
To hold brass use any of the above except brass
To hold ally use leather covered steel or wood
etc

Originally Posted by BobL

I have various sets of vice jaw covers,

Ally, brass, leather covered steel and wood.
Use goes with hardness of material.
To hold steel, use any of the above
To hold brass use any of the above except brass
To hold ally use leather covered steel or wood
etc

dont you use them for your wood working chuck BobL?

you have a Sherline wow thats a small machine it would hurt getting hit with something out of that tiny chuck lol a guy at work had to do a huge gear on the engine lathe it was more than 2' diameter and it flew out over his head........... you don't want that to happen. just use a nice over "nip" kind of pressure and if your doing hard cuts re-tighten after then just to be sure they can slip. to stop it marking (i think the marks are from burnishing) use the old can or thin brass shim it doesn't need to be hard but the point is that the brass is softer than the jaws so it doesn't mark the steel. i really wouldn't use leather it could end very badly!

hope that helped

Patrick

When I was in the trade and now with my lathe at home, all I ever use is soft copper or aluminium. Sorry Gavin, in my opinion ally cans would be far to thin if any decent pressure is used and if you have to much overhang would cut wondering fingers all to easily.

Squirrel...

Originally Posted by Squirrel

When I was in the trade and now with my lathe at home, all I ever use is soft copper or aluminium. Sorry Gavin, in my opinion ally cans would be far to thin if any decent pressure is used and if you have to much overhang would cut wondering fingers all to easily.

Squirrel...

good reason i second that

Haven't had a problem on either count thus far, I keep my fingers well away from the spinning chuck as a matter of course and I have less than half an inch of shim poking out, if that- just enough to act as a warning with the tools. I haven't had any marking through the ally shim, I may have been lucky but it works for me.

Rgds - Gavin

Originally Posted by Gavin Newman

Haven't had a problem on either count thus far, I keep my fingers well away from the spinning chuck as a matter of course and I have less than half an inch of shim poking out, if that- just enough to act as a warning with the tools. I haven't had any marking through the ally shim, I may have been lucky but it works for me.

Rgds - Gavin

I have also used aluminum from soda cans with pretty good success. I've even used a can unce wrapped around a workpiece that I was holding in a collet that left marks in the work because it had been previously abused by a student. I have also used aluminum cans as a protective shim in the mill vice when I was worried about marking the work. So far I haven't had any issues at all. Their uniform thickness, ease of cutting, price (free), and abundance make soda cans a decent choice in a pinch.

Edit: The soda can solution is best for those occasional times when you're worried about the work. If you find yourself turning to soda cans often, you might want to consider making yourself a set of soft jaws that fit in your chuck. You may even be able to buy a set of jaws for your Sherline - I'm not sure. If you decide to make a set, I remember seeing an article about it somewhere in HSM or MW, or maybe even MEW. I think the Author used a rotary table to cut the semi-circular threads in the backside of each jaw (it's been a while since I've seen the article).

Tyleryoungblood - I think the article you refer to was by Harold Hall in MEW. My memory could be flawed about HH, but I'm pretty sure it was MEW.

Sandy - You can buy soft jaws for many three jaw chucks, could be worth considering. e.g. Hare and Forbes can supply soft jaws for the chucks they sell.

If you're worried about the job coming out you could consider using some tailstock support. That should eliminate the prospect of getting hit in the face. Also keep in mind that the 4 jaw can hold the job far more securely than the 3 jaw. If the job is on the large size for the lathe, use the 4 jaw.

Originally Posted by blackfrancis

I think the article you refer to was by Harold Hall in MEW. My memory could be flawed about HH, but I'm pretty sure it was MEW.

Your memory hasn't failed you Blackfrancis. You're obviously not as old as me. It was in MEW Volumes 145 December 2008 and Vol 146 January 2009. Vol 145 discusses soft jaws and Vol 146 covers making them. I found the article very interesting and intend at some time to have a go at making some of them. I've pawed over the article and it looks like a very interesting exercise in machining.

I agree with the guys above, something, anything, that is uniform in thickness and still solid enough to prevent slipping can be clamped in the jaws between job and jaw.

Soft jaws are handy, as they also improve accuracy of turning as you can bore them slightly larger than job diameter (presuming it is round stock) then put job in and tighten, handy for facing short blanks etc. At least, this is how I have mostly used them anyways.

And to go back to first principles, if the work cannot be held securely in the chuck without over tightening the chuck then perhaps the method of workholding needs to be reviewed.

I draw a distinction between using shims to prevent marking of soft material because I'm clamping on previously machined surfaces and using them to compensate for having to over-tighten the chuck jaws to ensure the work is secure. If the latter is likely to be the case then I would look at using other methods of securing the work - tail centres, travelling or fixed steadies, turning between centres using dogs etc.

Rgds - Gavin

Hi
All of the above sounds like good advice, however there are two things not mentioned so far.
It is very important to check the condition of the chuck especially look for any bell mouthing of the jaws as this condition can spell disaster if the job is not held by the whole length of the jaw and even if it is it will cause trouble. The second is to try at all times to have the material supported right to the back of the jaws. I will sacrifice material to achieve this by leaving a part too long and remove the excess later, in fact one of the causes of bell mouthing is over tightening on parts held only at the front of the jaw.
Hope this helps
Ray

I completely fogot about bell mouthing.
with regard to holding to back of jaws, I too have always done this, sacrifice the stock after all it is only stock not the finished job.

Originally Posted by new_guy90

dont you use them for your wood working chuck BobL?

Yep , and sorry I didn't read the initial post properly and take notice of the fact that it referred specifically to lathes!

Here my WW chuck jaws with leather faces.

I made the chuck jaws at work using the ancient Nuttall metal working lathe - I love using that machine

When using the Nuttall and want to keep the jaw marks off I either wrap or gaffer small pieces of hard leather on the piece where it will make contact with the chuck jaws. It's no good for high precision work but its good for basic work and polishing.

I do a fair bit of metal polishing on the ww lathe with the leather faced jaws. I also have 2 ww vices and a cross slide DP vice with leather lined faces. These are excellent for holding brass bits while tapping and threading etc.