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Electronic Design

Bob's Mailbox

Dear Bob:
I enjoyed your "What's All This Drilling Stuff, Anyhow?" column (Electronic Design, March 4, p. 81). Here's a good 1/4-in. 4000-rpm drill: No, at $135, it's not cheap. Milwaukee builds first rate stuff, and I'm sure this is the last 1/4-in. drill you or your grandchild will ever need.

I have an old Black & Decker that still works, though, and I don't expect to upgrade, as it sees little use. I work with metal a lot, and the high speed is good for burning up bits. I recently discovered the advantages offered by air-powered drills. No, it doesn't do you any good unless you have an air compressor. You can get a pretty cheap, good, very high-speed air-powered drill motor from Harbor Freight—no plastic gears. A 2-hp (I know, don't get me started) compressor to run it will cost around $100 on sale. But it's handy for other things too. Plus, the air-driven drill is light and compact.

In addition to high speed, air-powered drills have an outstanding safety feature: near zero torque when stalled. I have a 1/2-in. electric drill that's nearly lethal when the bit grabs, say when drilling into an automobile frame. I recently bought a 1/2-in. pneumatic drill motor (geared, slow) because it fit into my tight work place. I found out that it had about as much running torque as the electric one. But it was safe to hold with one hand, off balance, because when the bit grabbed, the torque dropped to a very manageable level. My electric drill motor now lives on a shelf gathering dust. (Hmmm. Point nicely taken. /rap)

Here's an interesting note: Carpenters use drills to turn their drill bits. Machinists use drill motors to turn their drills. I think it's a matter of what one considers to be a tool.

If I had a lot of holes to drill, an air-driven drill might be a very good way to go. But most years, the amount of drilling that I have to do would not justify that!—RAP

Dear Bob:
Re: 1/4-in. electric drills. You obviously aren't looking hard enough. lists several 1/4-in. electric drills. For example, see

(Yes, but who the heck do they think they are—Enron? They think that they can make a conspiracy to cut off the supply, then force me to pay $139? A good 1/4-in. drill might cost only 3/4 or 2/3 of the price for a 3/8-in. drill—not 3× or 5×. I'll keep going to garage sales to try to find another one. Fortunately, I still have two that are in good shape! /rap)

Bob, I agree that the price is pretty high. But your allegation was that no one made them, not that what was on the market was overpriced!

I looked in hardware stores in 25 countries and found none. I didn't check out jewelry stores.—RAP

Your columns are priceless! Although I have sacrificed many coat hangers for tool purposes, my all-time favorite adaptation is the bicycle spoke. Decades ago I scrapped some junker bikes and saved the spokes. They're invaluable for retrieving dropped pieces in cramped engine compartments. The hook on the end is perfect, and their stiffness is ideal. Now I'll have to make some drills.

I must admit, I haven't used bicycle spokes much, other than as bicycle spokes. I usually use coat-hanger wire, or bailing wire. But, there's no hurry. These pieces of metal are just lying around, waiting until we need a drill in their size! Note that not all coat hangers are of the same gauge wire!—RAP

Dear Mr. Pease:
Please forgive my formality, but I have been reading your work for so long that I have raised you to near-deity status. (Obviously, you don't know me very well. /rap) Anyway, my guess is that you have had multiple responses regarding the use of various forms of flattened wire, etc., for drill bits. I thought I would let you know that the common term for bits like those you made is "spoon bits" (see for a picture). Such tools have been employed for quite a while (two or three centuries). Now they're primarily implemented in traditional chair making.

They work well, as you have shown, and are relatively easy to make. Also, have you considered using a small hand-powered drill rather than an electric 1/4-in. drill? I find myself leaving my electric drills in their boxes when I have only a few holes to drill.

I'm not one of the traditionalist wackos who only use hand tools, as my collection of 220-V equipment in my garage proves. But I have found that many hand-powered tools work at least as quickly for small jobs. Enjoy your columns/books/musings/etc.

I had over 100 holes to drill. An electric drill was quite appropriate. My homemade bits aren't terribly sharp, and high rpm is suitable for such drilling.—RAP

All for now. / Comments invited!
RAP / Robert A. Pease / Engineer
[email protected]—or:

Mail Stop D2597A
National Semiconductor
P.O. Box 58090
Santa Clara, CA 95052-8090

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