Subject: Drill Templates

From: [email-masked] (John W Bottoms)
Date: Wed, 12 Apr 1995 14:32:34 GMT

Drill templates have a bushing around each drill hold to guide the
bit to the correct location. I'd like information about how these
bushings are made (or purchased) and how they are held on the template.

-jb (Concord, MA)

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From: [email-masked] (Ken Marquess)
Date: 12 Apr 1995 17:04:41 GMT

>bushings are made (or purchased) and how they are held on the template.

They can be held in the jig a couple of ways: if you only need one diameter
of tool, e.g. you are just drilling, you can get ones that just press fit
in the jig. If you are doing several operations on the same hole (drill,
ream, counterbore, ...) you can get ones that are a slip fit, so you can
change bushing diameters between operations. These have a head that locks
with a retainer screw in the jig. (disclaimer - I've never used the
commercial ones - just read about 'em)

My recollection is that commercial bushings are rather expensive - several
dollars apiece and up. I've made a couple of poor man's jigs by drilling and
reaming the holes in a block of tool steel, and hardening the whole thing.
This worked adequately for my limited run application, and the few square
inches of O-1 cost a lot less than the bushings would have. The obvious
downside is that when the jig wears past the point of usefulness, you can't
just press in new bushings and resume. I only made thirty or so parts, so
don't know how long of a run you can get away with.

Jigs sure are the way to go if you have more than a few duplicate parts.