Soft jaws for a 3 jaw chuck

[stevec]

Last winter I decided to start a project to convert a surplus Cushman 3 jaw chuck to a "soft jaw" chuck for my 12 x 36 lathe.

The chuck didn't have the necessary 2 piece jaws so I wondered if they might be available.
Cushman didn't reply to my query for jaw possibilities so I thought about machining the existing ones.

The jaws laughed at my file hardness test. The file lay trembling in the file drawer.

So, with the recommendation of a buddy (on another forum) I put the jaws in the coals of my then constantly burning airtight stove.
Removed them to the constantly at hand ash can.
20+/- hrs. later the next day, after cooling slowly the file had it's revenge.

The jaws were soft enough to cut with my homemade bandsaw.

   

Next was the drill test to see if they could be drilled and tapped.

   

And now on to step 3 to machine the new, low tops on the jaws.

       

Here's the project now stalled, awaiting a threaded backplate for the lathe and finally soft jaws.

   

There has been some talk about re-hardening the jaw bases but I think I'll leave them as they are because I suspect they will get relatively infrequent use.

Back plate progress will be reported when and if it happens.

[EdK]

Those turned out very nice, just as they did the first time you did this project.

http://www.metalworkingfun.com/showthread.php?tid=1237

Ed

[Highpower]

(09-15-2013, 08:14 AM)EdK Wrote: http://www.metalworkingfun.com/showthread.php?tid=1237

Ed

Steve did you chop an inch off of your lathe bed? Last time it was a 12 x 37 lathe.

On a more serious note: You did an excellent job of reworking those jaws.

What kind of jobs would you normally use the soft jaws for?

[stevec]

(09-15-2013, 08:14 AM)EdK Wrote: Those turned out very nice, just as they did the first time you did this project.

http://www.metalworkingfun.com/showthread.php?tid=1237

Ed

Well you were the one that suggested I go ahead and post it.

[EdK]

(09-15-2013, 03:22 PM)stevec Wrote:

(09-15-2013, 08:14 AM)EdK Wrote: Those turned out very nice, just as they did the first time you did this project.

http://www.metalworkingfun.com/showthread.php?tid=1237

Ed

Well you were the one that suggested I go ahead and post it.

It'll make it easier to find next time.

[EdK]

(09-15-2013, 09:56 AM)Highpower Wrote: ...

What kind of jobs would you normally use the soft jaws for?

Willie,

They are good for working with thin pieces. An example is I needed a bronze thrust bearing for a project so bought one from McMaster. I needed it to be a certain thickness which was not available so I used a pot chuck to hold it in the lathe to face it off to the thickness I needed. Soft jaws on a 3-jaw chuck would do the same thing. I just didn't have one at the time so I made a pot chuck to hold the thrust bearing. That's just one example of what soft jaws can be used for. There are numerous uses for them that I'm sure some of the more experienced members can fill us in on.

Ed

[stevec]

(09-15-2013, 09:56 AM)Highpower Wrote: Steve did you chop an inch off of your lathe bed? Last time it was a 12 x 37 lathe.

On a more serious note: You did an excellent job of reworking those jaws.

What kind of jobs would you normally use the soft jaws for?

the first chuck jaw mods were for the 12 x 37, the second were for my 12 x 36.

OK, it must have come from converting from 304.8 mm x 939.8 mm
to inches. That's my story and I'm stickin' to it.

Apparently soft jaws can be easily turned so as to grip material concentrically and with good parallelism that might not exist with stressed jaws and chuck ways for the jaws.
If jaws are repeatedly used gripping items at the outer (closer to the tailstock end of the lathe) they may bend outwards from the centerline.
Soft jaws can be machined with a step in them for repeated location of parts for a production run.
I'm sure the list goes on but I need a beer and I'd have better luck with the dog fetching me one than my wife.

[stevec]

Hey Ed! he asked me! and I type slower than you.

[EdK]

(09-15-2013, 03:47 PM)stevec Wrote: Hey Ed! he asked me! and I type slower than you.

Your answer was better than mine so you win.

Ed

[Mayhem]

I thought this was a project I suggested annealing the jaws in but I responded to the post on the other thread whilst on my phone, so couldn't be arsed going to look for it

Once again, nice job Steve!