25 years ago, I built a few clock cases. My wife recently decided that we need a “School” clock so I built two cases of that style. The movements are German-made “Wind-up” movements of good quality.
Dealing with the front Time Dials is the next step in my work.
That is, this is the time to drill the Winding Arbor holes in the thin metal Dials. That’s where you put the key through the Dial to wind the three springs in such a movement.
When I’ve drilled thin metal, aluminum or thin steel in the past, I didn’t get clean holes—the metal peels up in a thin curl still hinged to the hole, sometimes. Or tears a little.
Please teach me how to drill 1/2″ holes CLEANLY in thin metal.
What type of bit? Is there a special bit for such a task? Where find?
Is a “Step Bit” the way to go?
Or———??
Any guidance will be appreciated. I don’t want to screw this up at this relatively late stage.
Many thanks,
William
Replies
If you can, clamp the thin metal tightly between two pieces of wood. Drill through the sandwich. The hole in the metal comes out clean.
I just drilled several clean holes through thin aluminum by clamping it between two blocks of wood.
PlaneWood by Mike_in_Katy
PlaneWood
The step drills have worked well for me. I usually drill a small pilot hole to start with, something in the 1/16" tp 1/8" range, because I'm not real confident of the step drill starting its own hole without wandering.
You can pop a small hole, just big enough to get a laminate trim bit, which is 1/4" dia, through it and flush route it to a clean 1/2" hole in a piece of wood. The burr will easily clean up.
William... My favorite method is to drill a 3/16" hole using my drill press then use a 'tapered reamer' to open the hole to the size I need. PLEASE take every precaution when drilling holes in thin metal. If the drill grabs the metal, your hands are trying to hold a spinning razor blade. If you must hold the metal with your hand, be sure to wear a HEAVY pair of leather gloves for safety. Using a SLOW drill speed and SLOW feed rate will help in working safely.
SawdustSteve
William
If you have access to a machine shop or auto body shop most of them have a metal punch that will cut a clean hole of different sizes. 1/2" hole shouldn't be a problem.
God Bless
les
Another option might be a 1/2" bimetal hole saw. You should be able to get three holes out of it before you lose too much of the edge. They have pilot drills to aid in getting the holes centered precisely.
Like another person suggested and you probably already know - clamp the work with two clamps. I wouldn't old something like this even with my welder's gloves. Go slow if you use the hole saw approach and use some cutting fluid or even motor oil to cool the bit.
Dennis in Bellevue WA
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