Soft Jaws

[stevec]

I'm kinda curious about setting myself up with a "soft jaw" 3 jaw chuck for my 12 x 37 lathe.
I have this old Cushman 8" (actually 7.5") ,
I'd like to dedicate it as a "soft jaw" chuck.
   

the existing jaws (3 only) are weird in that they don't have the "steps" on the backside for gripping the ID of material. No "reverse jaws".
Anyway I found the Cushman website and filled out the inquiry page regarding my "Cushman" 3 jaw *" Ref. No. 181" chuck and asking if 2 piece jaws were available.
Well the inquiry page responded with a "website cannot be found" message so I sent the message to <webmaster@cushmanindustries.com> but I don't know if I'lll get a response.
Here's a couple of pics of jaw "2.

       

They're hard enough to round the teeth off a file so I doubt if there's any chance of softening them to machineable soft in order to machine and tap.
Any advice or links to Cushman jaw suppliers?

[krv3000]

hi well if you have a mill mack a new set if you go to Harold hall,s web page their is a right up on haw to do it and drawings of the jig you need to mack to mack them as for making the ones you have in to soft ones cut the tops off with a cut of blade surf's grind them all the same height then with a diamond bur drill three equal spast holes and mack up sum threaded selves to go in to two of the holes and silver solder them up the third hole will be for a dowel pin to go in to that one will be the hardest to do as it needs to be deep to help support the jaw or just silver solder in blanks and drill and tap that's the way I'm planing to mack sum up for a chuck that i have hope this helps

[EdK]

Have DaveH (the other one) make a set for you.

Ed

[f350ca]

Steve, could you find some place with an EDM machine to cut them?

[TomG]

Anneal them, machine them for top jaws and re-harden. If you harden them in a stainless envelope, they'll stay pretty.

Tom

[stevec]

Bob, good ideas, thanks, but for me, too much work.
Ed, love that idea!
Greg, I live in the land of "you can't get that here" and coming from a guy that won't drive to an auto machine shop to get a couple of cylinders bored ???
Tom, Possible, could you suggest aan annealing procedure?
I'm still hoping for a reply from Cushman, there's no rush for this, I've still yet to make some soft jaws for the 2 piece jaws on my 16x60 lathe.

[Mayhem]

Steve - I've annealed hardened drill couplers by heating them to orange where you just get little sparks leap off the surface and them bury them in a bucket of ash and let them cool slowly.

I'm sure there is a more technical procedure but that is what worked for me. Then again, they were used for nothing more than scrap metal to practice with. With what you want to do, the oxidation will need to be limited and I'm unsure of the steps required.

So - come to think about it - this probably isn't any help at all

[TomG]

Steve,

There is a bit of guesswork involved if you don't know how much carbon is in the steel, but basically you heat it to about 1400º F and hold it there for a while (a half hour should do for a part that size), then let it cool slowly (30ºF per hour) to room temp. I would put the jaws in a stainless envelope or an air tight box to keep the air off. Know anyone with a kiln?

Making them hard again might be a bigger challenge since you don't know the alloy. They are probably an oil hardening steel, so heating them back to that temp and oil quenching would probably work.

Tom

[stevec]

Mayhem, I have plenty of ash, this being still the heating season.
Tom, I would be less concerned about re-hardening them, they wouldn't be used at a high enough frequency to cause much wear.
I'm concerned about heating them to 1400°F for a ½ hr.
Also, would oxidation change them dimensionally? As inthey would no longer fit the chuck properly?

[DaveH]

Steve,
Here’s the DaveH (not the other one) way
Light a coal fire – in an old steel container - when all the coals are red place the 3 jaws in the red hot coals. Make sure the jaws get nearly “bright” red hot then go and have a beer or two, just check they don’t melt Retrieve them next day, after they have cooled down.
They will oxidise and distort but they will still fit.

DaveH