Chuck Jaws

I have a 3 jaw Burnerd chuck on my Boxford. I only have one set of jaws, and the cost of another (external) set are about £120.0 - a new chuck is cheaper but i do not wish to go down that road!

As an alternative i have ordered a set of soft jaws for £25.00.

Do i tighten them down onto a bar and machine them outward to the required diameter or do i put a ring on the outside diameter and machine outwards!

And before any rivet counters answer i can not make jaws my skills are not that good. Even after looking at Harold Halls site who makes it look easy!!

Cheers Bri

Clamp the jaws in the same way as you would hold a job. On the inside and grind the inside of the jaws and on the outside for grinding the outside jaws. You need to remove any slop when holding the work. (someone correct me if this is wrong).

I can understand Bri your reservations regarding making soft jaws it really is only a practical proposition if you have a chuck for which soft jaws cannot be obtained, especially at £25 a set.

Paul is perfectly correct in his explanation of how the chuck should be clamped though as the jaws are soft then they can be turned rather than ground.

As I understand it you wish to produce the steps on the outer ends of the jaws for eventually clamping into internal diameters. This is marginally easier than machining the other end of the jaws. Wind, say three loops of steel wire, about 1mm diameter, around the outer end of the jaws and against the chucks face. Twist the two ends together to make it secure and then tighten the jaws into this by opening them up. With that done the the steps can be turned using normal methods.

If you wished to machine the inner end of the jaws a plug, onto which the jaws would be tightened, would be added. This would have to be as far back as possible still achieving a secure result, and the inner faces of the jaws machined. The result would be that a short un-machined portion would remain. The jaws would then have to be removed and this milled away.

There are some pages on my website explaining how to use soft jaws conventionally. Whilst this is not what you intend the explanations given are equally applicable to your situation. This can be seen here **LINK**

Incidentally, do you have a set of soft jaws, if not then you should have purchased a second set. I worked without them for many years but now wonder how I had managed without them.

Just in case some readers are not aware of the pages on my website that you mention they can be viewed here **LINK**

Harold

Hi Bri & guys
I f you are going to turn say a disk componet about 2&1/2" dia x say 1/4" thick as paul says clamp down on a peice of say about 1" or smaller dia back in the chuck so there is room for the "job" as they are soft you can bore/turn out about 1/8 deep to the correct dia 2&1/2 " if its a repitition job make sure you make a note whitch one tightend up on . The jaws should be numberd I am assumeing you want to hold large disk like  diameters
Nobby

Edited By Nobby on 19/03/2013 22:29:30

Can I also add.....number jaws before "chuck choping".(if not already done when bought)..

too easy to forget after....

also for best concentricity..and future economy..turn outer to holding size not some general purpose diameter....if you see what I mean..think expanding mandrel..

Soft jaws are a real benefit, once you have a set you will not want to be without them. My tip is to recycle them when you have machined them down a fair bit. When they have about 1/2" thickness left, machine them flat, and then carefully mark out and drill and tap a couple of holes in the centre of the jaws. Then make up some mild steel blocks to match the section of the jaws, and drill and counterbore holes to match those in the jaws, make the clearance holes as small as possible. The counterbore needs to be as deep as possible, then secure the blocks to the jaws with cap head screws, and you have some new jaws, almost free. I drilled mine carefully using a DRO to position them, and I made many sets while I was at it. I have been using the same base jaws for about 30 years, changing the blocks when needed. I have to make a new batch of blocks soon, but the scroll teeth on the base seem as good as ever.

Chris Gunn