4 jaw chuck

Post by **GlennW** » Mon Mar 23, 2009 12:49 pm

Now that's funny!!

Post by **Harold_V** » Mon Mar 23, 2009 2:03 pm

Glenn Wegman wrote:Three jaw is better than six. I just stuck my knuckle in my six jaw and got hit twice as many times before I could get it out

Ouch!

Harold

toastydeath · Post by **toastydeath** » Mon Mar 23, 2009 2:10 pm

I am not trying to be a big confrontational asshat here, but this is my experience so far in a production shop. Take this for what it is.

I find soft jaws have superior clamping on out of round parts and scale. When one crushes the part with hard jaws, it releases some of the clamping pressure from deformation. A soft jaw will smoosh up and conform to the surface of the part, and then apply a ton of force without releasing any of it through plastic deformation. There is a limit to how much force you can apply to a hard jaw since it's essentially a line contact. Keep applying pressure, and the part just keeps deforming without any additional holding power. With soft jaws, there's three really nice and large surfaces for you to apply a larger total force with, while keeping the surface pressure lower. I'd much rather have hot rolled in a pair of soft jaws if I'm going to be taking big chunks out of it.

I do understand that the home machinist has to weigh the time and cost of using a soft jaw. That is the subtext of what is being discussed, I think. My shop has like, shelves and shelves of soft jaws of all sizes and diameters. We always have a bunch of fresh ones, just in case we can't find an appropriate old pair to recut. That's not really a luxary the home machinist has, and if softies were cut every time one a part was required, there wouldn't be much money left for anything else.

And come on, who's going to throw on a pair of soft jaws, bore them, and then turn a part from rough stock just to make one little pin or something because the little pin that holds up the shelving in your TV cabinet fell out? Not me, kind sirs. That job is getting held in whatever my hands grab first.

That being said? Soft jaws are the bomb. There's no reason to use hard jaws except expediency and cost. Which are pretty big reasons, all things considered, but they aren't technical merits.

Old Biker UK · Post by **Old Biker UK** » Mon Mar 23, 2009 4:00 pm

FWIT here's my el cheapo soft jaw chuck. Beat-up chuck, free from scrap yard, jaws in a bonfire for a couple of hours, cooled off, machined flat, drilled & tapped 5/16". Soft jaws - anything you like, these are 1.5" free cutting MS hex., drilled & counterbored for cap screws.

Takes about 5 minutes to set up a plug in the original jaws, tighten up & bore to size.
Used a few times as you can see, need a new face, turn the hex around.

Mark

steamin10 · Post by **steamin10** » Mon Mar 23, 2009 5:43 pm

Biker, you kill me. What an idea, rotating jaws for use/reuse. Killer Idea. Thanks for that one. I got an older chuck that is cranky , and need a new backer c/o sombodys WRECK. (Not mine). It is a name chuck, that I cant remember rightnow. But this would be the great idea to use it.

lakeside53 · Post by **lakeside53** » Mon Mar 23, 2009 8:03 pm

Hmmm... I was going to use an old chuck as a welding fixture.. but now...

So.. are jaws on good chucks hardened throughout, or just case hardened? What alloy steel do they use?

neophyte · Post by **neophyte** » Mon Mar 23, 2009 11:19 pm

Just picked up a 4 jaw (Self centering) 3 bolt mount chuck for my V10P. New. It is czech. in origin and I got it thru a supplier in England. Quality seems quite good. I also have a 4 jaw Emco (independent adj.) The 4 jaw was an alternative to 3 jaw. We will see how it works out.

lakeside53 · Post by **lakeside53** » Mon Mar 23, 2009 11:23 pm

Interesting. I picked up a Rohm 6 1/4 inch 4 jaw scroll+independant adj, but it sure is heavy... makes me wonder if it's a bit much for my emco V10P...

neophyte · Post by **neophyte** » Tue Mar 24, 2009 7:37 am

I have a 4 jaw (indiv.adj.) Emco Chuck for the V-10P. It is just about 6" in diameter but appears to be a thin body,reversable jaws. (Less than 2" thick) I haven't had a problem with it yet.

BTW I also have this USED Emco 3 Jaw SC 110mm that was left with the tooling on another machine (three bolt mount). I will probably sell it on E-bay or part with it outright/trade. Won't need two chucks. Looks fairly clean but has small knicks on body from having tools piled on it . Have not mounted it on my current lathe so it is sold AS IS. (Spare Outside jaws should still be available from Blue Ridge.) Can provide more pics. Comes with a Key.

These are the three bolt mount - short taper models. If you are interested here are some pics. Trades ?...... I need a fixed follow rest and a steady rest...
Thanks g.fritz@juno.com

Jose Rivera · Post by **Jose Rivera** » Tue Mar 24, 2009 12:17 pm

Old Biker UK · Post by **Old Biker UK** » Tue Mar 24, 2009 1:00 pm

lakeside53 wrote:So.. are jaws on good chucks hardened throughout, or just case hardened? What alloy steel do they use?

I don't think the chuck was ever a 'good' one but the jaws were hard,
no idea about the steel or hardening method but a couple of hours in a wood burner made them quite tool friendly.
Mark

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4 jaw chuck

4 jaw chuck

4 jaw chuck

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