"Shimming" barrel to fit lathe?

[LRShooting]

Just based on 50 years experience with lathe chucks?

It does.

You looked at the big picture.
Not the fine details you had no idea what you were looking at..

Please excuse me for my blunt assessment of the lathe, and your view of it.

But, that's my story, and I'm sticking too it!.

rc

I didnt mean it that way, but yes I didnt see the small details. I seen a chuck that was too big to fit my barrel the way it was "currently" set up. Ive been constantly busy with Xmas this year so I haven't had time to go over there and see some of the stuff thats been talked about and what not. While I like the "Spider" idea, Im not for sure if I wanna buy a chunk of aluminum like that. Not that its super expensive, but its not real cheap either. Im pretty tight right now. Surely I could find something around here that would work. There is tons (literally...like in the hundreds if not thousands of tons) of scrap metal and junk laying around.

 

[LRShooting]

Nevermind...I take that back. Just looked at onlinemetals.com, and even with their elevated prices, I can get a 1 inch by 1 foot chuck for 7 bucks. Still have that issue of finding a morse taper with a chuck. Those are pretty pricey. I would be better off buying a new barrel from lothar walther.

 

[Mr.510]

If you've got scrap steel laying around you could make the quick and dirty collet I described out of steel it's just much slower to machine and you might have to add a couple partial cuts in from the OD to allow it to flex more easily if it's very heavy wall. You could make it out of PVC pipe or just about any other common plastic, for that matter. A piece of hardwood would actually work too. You won't have much tool load crowning a barrel so you don't need a super rigid setup. You're dialing it in with an indicator so the squish of wood doesn't matter. Just throwing out budget friendly ideas.

You could also use blocks on the jaws to reach the barrel. That's completely acceptable in the machine trade so long as they cannot fly out. I didn't suggest it because you could damage the finish pretty easily messing around with a four jaw and blocks. A good trick is a few even wraps of electrical tape to help protect the finish. You can also tape spacer blocks to the jaws with electrical tape to make it easier to get them and the barrel in place. Just be sure the blocks are all clamped in place firmly (not just taped!) before you start the spindle. Things flying out of spindles carry tremendous energy. I've thrown a part 60 feet and stuck in the wall 20 feet off the floor!

 

[LRShooting]

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[LRShooting]

Pictures Update

Sorry about the wait. Ive been pretty busy and I tried yesterday, but I couldn't upload the pictures. Due to lack of having a tape with me, I put a wrench up the chuck to give you an idea of size. Both chucks have the same design, but the 3 jaw simply closes tighter due to having one less jaw to take up space. Id say the chuck is 3/4 to 7/8 minimum size. Picture of the whole lathe just gives you an idea of size. Not huge, but it definetly needs some TLC. I checked all the bearings on the spindle, but nothing gives. I used a pipe to apply pressure just to make sure it wasnt the weight holding it solid. Soo it should work fine as long as I have some good tools. Ill probably get some carbide inserts because they are fairly cheap and I have a few parts that need carbide tooling.

My barrel diameter is 15 mm, so a little less than 19/32. The other parts are between 1 in and 1/8 of an inch which ill just find an old drill chuck and use that. Itll work...I think .

Thanks for all the help and advice, but I just figured pictures might help if somebody came up with any ideas. I like the spider rig, assuming I can make it.

 

[LRShooting]

:banghead::banghead::banghead: Still didn't attach themselves...Sorry about that!

 

[12Bravo20]

MR 510 is correct. Making your own collets isn't hard. I use to do it all the time when I worked as a tool and die maker. I've used lathes of all sizes from micro lathes to vertical lathes with 120 inch tables. Machining a three piece 120 degree Babbitt bearing with a 102 inch inside diameter is fun.

 

[LRShooting]

 

[jmorris]

I can believe the 4 jaw can't touch a small diameter barrel.

This one is not even gigantic and wouldn't clamp most barrels (even if the jaws were reversed for smaller objects).

Just look at the "flat" between the clearence angles on either side, where they would touch one another.



The smaller 3 jaw inside the 4 jaw idea would work.

The spider is a good idea too. For the utmost precision you want to have a spider on the other side of the spindle (side opposite of any cutting) too.

 

[LRShooting]

I can believe the 4 jaw can't touch a small diameter barrel.

This one is not even gigantic and wouldn't clamp most barrels (even if the jaws were reversed for smaller objects).

Just look at the "flat" between the clearence angles on either side, where they would touch one another.



The smaller 3 jaw inside the 4 jaw idea would work.

The spider is a good idea too. For the utmost precision you want to have a spider on the other side of the spindle (side opposite of any cutting) too.

Your chuck looks exactly like mine, just cleaner. Same size and everything comparing it to the calipers.

 

[4v50 Gary]

I'd rather use shims with the four jaw and dial off the barrel (or a bore stud) to ensure that it is concentric.