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Tharpo

Member
I knew this thing was hard B/4 I started...(didn't know the half of it.)What did you guys use on it ....solid carbide maybe?
Thanks
Tharpo
 
Work Slow

The thing I was concerned about is "work hardening". Let the drill turn without cutting and it "works" the metal making it much harder and very difficult to break through the hardened zone.

Using plenty of cutting fluid.

Just the right amount of pressure. Backing it off, the bit stops cutting and just spins on the substrate causing works hardening.

I cant remember what the exact details of the bits I used for this and the landing gear but they came from Aircraft Spruce and were amazing. One of those drill bits drilled all 4 holes and was still sharp. The drills I bought here in Australia might as well have been made of licorice.
 
Unless you have a very nice drill press or even a mill, I would avoid using Carbide. It is very hard and cuts the gear legs very well, but it is also brittle.

If you bend a carbide drill even a little, or if it gets caught on the bottom of the hole when breaking through, it will break. If you think the hole is hard to drill, it is MUCH worse when there is pieces of broken carbide in there!!

You should use a Cobalt drill. MSC has them at reasonable prices. I usually drill the hole either 1/64 or 1/32 under size and then ream to size with a cobalt reamer also.

Always use cutting fluid and don't spin the drill too fast. Most holes can be made quite nicely at 300- 500 RPM.
 
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