Milling small holes in Aluminum XZ Plates

LowRider CNC Advice
1

I’m getting set up to mill out my XZ and YZ plates in 1/4" aluminum. I’m planning to use a 1/8" single flute end mill trochoidal milling for all of the slotting and larger holes, but the eight smaller 3.2 mm holes in the XZ plates are pretty much the same size as the end mill, so trochoidal won’t work on those holes.

It seems to me that the options are:

  • a straight plunge through the entire depth (6.35 mm) with the same 1/8" flat end mill (not ideal, from what I can gather),
  • changing out the tool for these holes to a 1/8" drill bit,
  • changing out the tool for these holes to a 1/16" flat end mill, and using trochoidal milling
  • changing out the tool for these holes to a V bit and making a pilot indent, and then drilling the holes on a drill press with a 1/8" bit

Which option would be best in this case?

For the YZ plate, I was thinking to thread the smaller holes for a 3 mm machine screw by making them 2.5mm diameter, so a 1/8" drill or end mill won’t work at all here. This limits the options to:

  • changing out the tool for these holes to a 3/32" drill bit,
  • changing out the tool for these holes to a 1/16" flat end mill, and using trochoidal milling
  • changing out the tool for these holes to a V bit and making a pilot indent, and then drilling the holes on a drill press wit a 3/32" bit.

Again, which option would be best here?
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2

@Bartman

I did the third option: Just make a dimple and the drill the hole the correct size of the drill press, followed by taping.

That way the alignment is correct and the linear rails are parallel.

Mike

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3

I would go with the pilot indent, too. It would allow a 3/32" drill, which can be M3 tapped, best solution, IMO.

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