Which chuck on which machine?

[great white]

I’ve just received a couple older Jacob's chucks. One is a 16N superchuck and the other is a 633C. They’ve got thier battle scars (hammer marks), but on tear down they are mostly just dirty and old. They seem in decent shape otherwise.

I’ve got a drill press and a vertical mill. Both have chucks already, but they’re the cheap china sheet metal barrel things. So I want to put the jacobs chucks on these machines.

Which chuck should go with what machine?

I don’t really have a reason for it, but it seems to me the superchuck should be on the drill press and the 633 on the mill.

Anyone have any input on this?

 

[mmcmdl]

Depends on run-out ! I would use the best of the 2 on the mill .

 

[benmychree]

Depends on run-out ! I would use the best of the 2 on the mill .

If the super chuck and the 633C are equal in runout, I'd use the superchuck on the drill press.

 

[great white]

Got it. TIR is the deciding factor and tightest tolerance on the mill.

They're in pieces right now (in the ultrasonic) and I'll need to clean them up, stone the burrs and put them back together. Then I'll check runouts....

 

[compact8]

Got it. TIR is the deciding factor and tightest tolerance on the mill.

Just would like to share my experience on measuring TIR on my Emco FB2 bench mill. The spindle uses morse taper 2 for mounting and the inner wall has got a TIR of 0.007 mm or 3 tenths of a thou. I have got a Chinese-made ER25 collet chuck and a keyless 3-jaw chuck ( ROHM , made in West Germany ) , both have some eccentricity and I need to mount them at a specific angular position relative to the spindle to minimize the overall TIR. In the best case, the runout of the chucks are the same as that of the spindle so they can be made to cancel out each other perfectly. This does not happen in my case but I can prevent them from adding up. Now the total TIR is within 0.025 mm or a thou for the collet chuck and 0.035 mm or about 1.5 thou for the keyless chuck which is good enough for me.

The minimum TIR position is marked on the spindle and the arbor :

 

[great white]

Well, the small chuck has about .005 run-out on the mill quill. About the same as the cheapo chuck that came with it stock so I left the Jabobs on the mill quill.

The ball bearing chuck is another matter. Cleaned it up, assembled it and dropped it in the drill press taper, I used the MT3 arbor that was already in it, mainly because I can't get it to release from the chuck, even with a drilled hole and a punch. Even tried heat and cold, no go, stuck like heck. Probably been on there 40-50 years.

I get it in the drill press and hit start. No need to put a dial gauge on it, I can see the wobble with unaided eyes. And it's not like it's something I have to look closely to see. It's really, REALLY bad.

I need to get the old beat up arbor out and try a new one that isn't pitted and beat up. Too bad the arbor is so beat up, it's an original Jabobs arbor. I suppose it's possible the chuck housing is bent, but it woudl take one heck of a hit to bend it this much.

Maybe someone dropped this big boy to the floor and that might have bent the housing....I don't find that likely, but you never know. Dropping this much metal 3 feet to a concrete floor carries more force that you might think.....

 

[jmkasunich]

The ball bearing chuck is another matter. Cleaned it up, assembled it and dropped it in the drill press taper, I used the MT3 arbor that was already in it, mainly because I can't get it to release from the chuck, even with a drilled hole and a punch. Even tried heat and cold, no go, stuck like heck. Probably been on there 40-50 years.

I get it in the drill press and hit start. No need to put a dial gauge on it, I can see the wobble with unaided eyes. And it's not like it's something I have to look closely to see. It's really, REALLY bad.

I need to get the old beat up arbor out and try a new one that isn't pitted and beat up. Too bad the arbor is so beat up, it's an original Jabobs arbor. I suppose it's possible the chuck housing is bent, but it woudl take one heck of a hit to bend it this much.

Shame about the arbor. Some advice for getting it out of the chuck: if the arbor is no good anyway, don't abuse the chuck trying to get it out. Just sacrifice the arbor.

My story: some years ago had a nice Jacobs with an arbor that wouldn't come out. We tried everything and were about to give up. Then realized that while the arbor is made of nice steel it still isn't hardened like a cutting tool. We bandsawed off most of it. Then put the Jacobs chuck in the 3-jaw on the lathe with the arbor stub facing out. Drilled it thru (you can tell when you reach the end of the arbor, there is an air gap between the end of the arbor and the bottom of the taper hole in the chuck). Then started boring until there was only a few thou of metal left of the original arbor. Finally was able to peel it out. Seems some crazy former owner had stuck it in there with red locktite. Took a bit of time but when done the Jacobs chuck (including it's taper hole) was unharmed.

 

[great white]

Well, got the arbor out. I ended up cutting it off nearly flush to the chuck, drilling most of the rest out and I had to make a 7/16 hole in the chuck itself to get a big enough punch on the back side of the arbor.

Even then, it did not want to come out. Heat, cold, etc…just would not move. I even had it pressed in the large bench vice at one point, crushed with a 3 foot cheater bar and the vice locked up so solid it wouldn’t go any further. Tried heat and cold again with it under vice pressure, no go.

I finally ended up on the floor on top of a steel anvil with a fabricated punch (sized exactly to the 7/16 hole to give it as much strength as possible, anything smaller would just bend) and beating on the punch with a 5 lb sledge. I figured no way after the vice refusal, but it finally let go after 5-10 hits. Once apart, I could see a very thin coating of rust on the taper and chuck bore, so the arbor and chuck had likely almost “welded” themselves together.

I already had the chuck apart again to do the abusing work, so I chucked the main body up in the lathe and shaved a thou or two off the exterior surfaces. None of the critical dimensions were touched, except skimming about 2 thou off the face where the jaws come out. Cleaned up all the decades of abuse and hammer dings. Not all of them, but most so it just looks like a regular used chuck. The gear ring was in decent shape, so I didn’t touch that other than a degreasing and cleaning.

While it was apart, all of it got a good scrubbing and drying. I also stoned a few more things internally and gave it a good coat of white lithium grease. Movement is now buttery smooth.

Dropped a new JT3 arbor in the chuck and after a little massaging, got a TIR of 0.0045 with a 5/8 end mill chucked up to give a running surface for the dial indicator. Thats 0.0045 TIR about 1.5 inches away from the tip of the jaws. I’ll call that “acceptable”, especially for a drill press Where the runout is about 4 thou to start with.

Heres a couple pics of the finished product:




When I get a few spare minutes, I’ll probably grab some “Neverdull” and give it a good final polish/buffing.

The jaws are “ok”, but they do show some wear internally.

I’ll be keeping my eye out for a NOS rebuild kit and I’m also going to have to order the correct chuck key, but not bad for 25 bucks and a couple days work….