Drilling Tips

With so many holes that need to be drilled in a typical GlaStar or Sportsman, it pays to learn some tricks to do it right the first time.

pneumatic-drillAir Drills: I took my new little Sioux 1/4″ air drill to Ottumwa. Everybody in the class borrowed it at one time or other. It would disappear the minute I took my eyes off it. Everybody loved it. Several new ones appeared on various work benches before the class was over. There is no comparison between this drill and the others available on the market today. Even a complete novice will notice the its superiority immediately. It is a little more expensive but well worth the extra money. Get the 3,600 rpm one. If you ever took the time to do the math to determine what the proper cutting speed should be for the size of the drill bits you required for the GlaStar you will find that even 3,600 is way too slow, but it is the fastest one that I know of. You will have 10 zillion opportunities to drill a bad hole in the GlaStar, you need to have everything you can going for you. The “Sweet Sioux” will definitely help you do a much better job.

–John Top


Uni-bits: When using Uni-bits, rather than using a pneumatic drill or an electric drill without a speed control, use a good electric screwdriver — a commercial-grade electric screwdriver, not one of those $19.95 jobs. The good ones work great with Uni-bits. You can control the cutting speed and the alignment better, and the result is perfect holes. Well, they sure look perfect. When I first spent about $125 for the screwdriver kit (with carrying case and spare 9.2v battery), my friends thought I was crazy. I note with some pleasure that some of them now have identical units. One later told me it was the best tool purchase he ever made. Don’t knock it until you try it. The good ones are excellent tools (particularly at annual time when many, many screws come out and go in).

–Joe Colquitt

Hole size: A drill never drills a hole that is the correct size, and it does not drill a round hole. This is because the point is not ever truly in the center and also if you look at one you will see that it is not a point, but a straight line. Therefore if you want a round and true hole you drill to about 10 or 15 thousandths undersize and ream to final size.

A reamer must always be run in the forward direction. Do not ever remove it from the hole it has just reamed by turning it backwards or pulling it straight out. Also do not set it on the flutes. They come in little cardboard tubes for that reason.

On the subject of drills – I bought a gadget called a Darex Drill Doctor from Cleveland tool while I was at Sun ‘n Fun. What a neat item. It sharpens a drill perfectly every time and in about 30 seconds total. Cost me $129 and worth every penny.

–Tom Lempicke

Easy aluminum drilling: Keep a shotglass of aluminum tapping fluid handy when you are drilling holes or using your countersink in the forward spar (or any aluminum for that matter). Dip it every third hole or so and your tools will last several times longer, not to mention the faster, easier cutting they will do. Tapping fluid is available at any tool and die supply house. Steel fluid is different from aluminum fluid, and your shop should have both.

–Tom Lempicke

Drilling stainless steel:

  1. Use very very VERY LOW RPM on the drill.
  2. Use very HIGH feed force. Don’t break the bit, though. Watch and listen and you will see nice drill chips forming if you are doing it right.
  3. Use a new drill bit. If you overheat the bit, throw it away.
  4. Use coolant. Water and cutting oil both work. KEEP IT VERY COOL!

Stainless work-hardens very quickly. If you botch it once, you may not be able to get a drill through it again. If you get it really hot during drilling, the surrounding material chills and tempers the steel very locally. We are talking super-hard here!

–John Coussens, Stoddard-Hamilton

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