8/12/2019 Chuck Truing Jig

1/1

R

UN OUT affects

even the best of

chucks after years

of use. Homemade tru-

ing ring will bring

back true running

within .001 in. at the

stock size range you

use most often.

Chuck holds truing

ring just as it would

a piece of work, yet

jaw faces are free so

they can be bored or

ground concentric and

parallel with the spin-

dle. All you need are

four steel rings plug

three 10-32 in. h ex

head screws to make

it.

Cut large master

,'ring from 0/16in. thick

6-in. diameter steel

tubing. If you can't get

i~ : :~~~~~~~~E

rue Up That Worn athe huck

Three smaller rings are %6 in. wide slices Mount truing ring so that one of the smaller

from lfs-in. wall 1% in. diameter steel tubing. rings fits over each of the three jaws. Then

Cut smaller rings with beveled slot to fit over tighten jaws until you feel slight resistance.

chuck jaws. Exactly opposite opening, drill Remove the stock from the chuck and re~...

a %6 in. hole in each of the smaller rings. In tighten it until the smaller rings begin to

the large ring locate %6 in. holes at three expand. Ring holds chuck in suspension with

equal intervals. Tap all holes 10-32 to match jaws free for grinding.

screws and assemble truing ring as shown. Hardened jaws must be ground. If an in-

To use truing ring, chuck a piece of round ternal grinder is not available, and jaws are

stock of the size you use most often. (Due not hardened, light boring cuts of about .003

to wear on parts other than chuck jaw sur- in. to .005 in. can be taken to true chuck.

faces, truing ring can help make chuck really After truing, rechuck stock blank and

accurate at only one size, but may well im- check your job. It should run true within .001

prove its accuracy throughout the size range.) in.-RIcHARD O. KONOPKA.

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FIG. 1: Truing ring supports lathe chuck jaws, internal grinder trues worn faces.

1

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J

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3

DRILL j6t 3 HOLES

RING

AND JAWHOLDERS MADE OF MILD STEEL ,DIMENs.IONS GIVEN

MAYBE ENLARGED.FOR CHUCKS WfTHiARGEFrCAPACI.TY

FIG. 2: Set truing ring dimensions to flt your chuck.

Steel tube can be only 5/16-in. thick instead of i ii-in.

thickness required if made from steel pipe as shown.

DECEMBER, 1962

FIG. 3: Detail shows how small ring supports ~huck

jaw for grinding. Hex head 10-32 3/16-in. scrE'Wad-

justs ring to hold jaw when test bar is removed.

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