Drilling for Helicoils

ribbitt and Company --

Here's a heck of a clever way of guiding a drill and getting the drillmotor into a place where it would be pretty darn hard to hold by hand.

The long, multi-hole guidebar is very functional in that one particular application, but a much shorter single-hole guidebar would make a very handy tool for more general use.

The link is for what I think is the clearest picture, but there are three more and a written description of the problem and solution. Drop the "/_2001_retired_files/studs_from_hell_1.jpg" from the URL to get to the index.

John

• Homemade drilling machine for close quarters

Thanks

Carol

I've never used Bud's emery cloth trick personally, but I've heard of and seen two variants of the same idea. One version a single layer of "emery" cloth (in today's world the abrasive is probably aluminum oxide rather than emery, but the difference is inconsequential for this use). The piece of emery cloth only needs to be a bit bigger than the hole you're trying to drill . . . but too small a piece is hard to handle. The guy who showed me this trick used a two inch square of emery cloth torn from a roll, and let it turn with the drill.

The other variant I've seen is using several layers of plain cloth instead of the emery cloth. One guy I used to work with simply folded a wiping rag into quarters and drilled through it.

John

Rule 1 is to use a mechanically-guided drillmotor whenever possible. Something as simple as a drill guide (a block of metal with a correctly-sized hole drill-pressed through) clamped to the work so that the hole in the block is in line with the should-be hole in the work makes the job MUCH easier.

Other thoughts include using a countersink to champher the stripped-out hole before drilling, grinding the drill to put a sharper point on it, rounding the sharp corners where the drill point intersects the margins (the OD of the drill) while being sure to maintain clearance behind the cutting edge, and "dubbing" the drill by stoning or grinding small flats on the cutting edges (where the flute surface intersects the point) to reduce the hook.

John

Carol