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View Full Version : Your tricks for juggling shims?



ScottyM
03-08-2010, 08:27 PM
Ok, you've just turned some small part and now need to turn it around in the chuck to perform a second operation on that end. You have a nice finish, and it is exactly where you want it for size. What tricks have you come up with for getting the part mounted along with some shims to prevent jaw marks. I swear I'll drop shims in the chip tray multiple times before I finally get everything where I want it. Somedays it makes me wish my chip tray was a cooler. The best I've found so far is using rubber bands to hold the shims, but then you cut the bands with each part.

Scotty

lane
03-08-2010, 08:32 PM
I use 3x5 cards for that purpose , and a pair of scissors.

Mcgyver
03-08-2010, 08:34 PM
just use a strip of sheet metal; buy a roll of steel shim stock, and cut a strip wrap it around the work. i've also a box of copper strips, but that's for lathe dogs as the copper is soft enough to deform (and therefore not keep its dimension)

Toolguy
03-08-2010, 10:30 PM
Just use masking tape. It has a hundred uses in the shop. You can put it on the chuck (or mill vise) jaws or the part. When finished, it peels off easy. Works good on the X + Y dials to keep them in place if the handle wants to rotate down or the cut is causing vibrations. Put half the tape on the part with numbers and half on the non moving part next to it. An inch or two will hold it pretty solid.

nheng
03-08-2010, 10:36 PM
Paper, index card or aluminum roof flashing depending on how hard it needs to be gripped (and protected). Usually, I wrap it around the part and pinch together and exit at a point between jaws. Den

Machinist-Guide
03-09-2010, 12:29 AM
I cut the shim the size of the clamp area of the chuck jaw and wipe wax or grease on the shim to make it stick to the chuck jaw

pipeclay
03-09-2010, 12:44 AM
Grease works for me as well for small shims.

becksmachine
03-09-2010, 12:49 AM
Use material that is heavy enough to bend tabs up and around the step in the jaw. They hold themselves on.

Dave

gearedloco
03-09-2010, 12:52 AM
I cut a strip out of an aluminum can that almost reaches around the workpiece.
The length makes it easy to hold while mounting it in the chuck.

boslab
03-09-2010, 01:32 AM
dab of hot melt to each jaw/shim when its set up, it holds them nicely and does no damage.

Evan
03-09-2010, 03:50 AM
Use a split ring cut from plastic pipe.

willmac
03-09-2010, 05:39 AM
Aluminium drink cans are great for this as already noted. I keep a supply already cut up.

For really fine/small work I use the thin plastic strips that you pull out of toner cartridges. This has a very consistent thickness and is coated with something that seems to give it a bit of grip. The base tape looks like Mylar but may be something else.

quadrod
03-09-2010, 06:38 AM
I second the coke can shim. Works well.

oldtiffie
03-09-2010, 06:40 AM
Ok, you've just turned some small part and now need to turn it around in the chuck to perform a second operation on that end. You have a nice finish, and it is exactly where you want it for size. What tricks have you come up with for getting the part mounted along with some shims to prevent jaw marks. I swear I'll drop shims in the chip tray multiple times before I finally get everything where I want it. Somedays it makes me wish my chip tray was a cooler. The best I've found so far is using rubber bands to hold the shims, but then you cut the bands with each part.

Scotty

I note that it is a "small" part - how small?

If its quite small relative to the chuck, the jaws will grip on their curved centre and not the sharp edges at the sides.

What is it that requires you to grip it so hard that it marks the job?

No collets?

Have you actually turned a trial or sample to see if the jaws will actually mark the part or are you just "thinking about it"?

If not, why not try it first and see if there is a problem that needs solving.

Scishopguy
03-09-2010, 03:23 PM
Me, I like duct tape, the handyman's secret weapon. Wrap the tape around the part to be gripped, being sure not to overlap it or it will throw off the center. Cut it short or do like Den says and pinch the ends together between jaws.

knudsen
03-09-2010, 03:33 PM
I cut the shim as wide as the chuck jaws and about as long as I think it will take to go around. It's always a bit long, so I wrap it around and then trim for a small gap. It stays good enough. When finished, I toss it in the chip tray to be used later or get smashed somehow then tossed with the chips.

ScottyM
03-09-2010, 08:17 PM
Great bunch of ideas guys, thanks. I never had thought of slathering a little grease on it. I'm going to try it just because it's so simple. I tried masking tape but my chuck jaws are usually so oilly that it won't stick. Tiffie, I guess I don't really have an explanation of why I chuck things that hard. I've just had too many things either get pushed back into the chuck or spin in the jaws, and then I'm cussing again. My usual shims are some brass that I cut down to about 5/16" or so wide and about 1/8" thick. As to how small, my parts maybe anything from about 4" dia. or less. Once in a while a little larger. The particular part I was working on that prompted all of this happened to be an odd dia. so that collets wouldn't have worked. The cut up aluminum can is a good idea, only problem is I fond of things that come in a long neck bottle. :D Those wood make lousy shim stock.

Thanks again,
Scotty