How to machine a metal slot/hole

The flats on the motor shaft are probably just bearing surfaces for set screws. I've seen bores like this, but only in punched sheet metal parts where fit is not an issue. Actually, as drawn, this hole can not be machined, only punched or broached. If you want to go into mass production, punching 5mm alum is not a problem.

Would it be too obvious to just bore a 10mm hole and then put two set screws in? This pulley doesn't look like it will be under too much torque load, so two (even one) set screws would be more than adequate. If you're into heavy torques, the shaft would bend first.

Bruce

Reply to
sawdoc
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The set screws are definately an option I'm looking at, although first I want to try milling a rectangular hole but with rounded corners.

--Amr

sawdoc wrote:

Reply to
Amr

If you have a bit of extra hub thickness to work with, make a shallow flat-bottomed hole the diameter of the shaft on each side; then make your rectangular slot; then file the ends to match the edges of the flat-bottomed holes.

Reply to
jtaylor

If you really want to mill the slot, you can't just do it with a 5mm end mill because it can't give you the sharp corners. You'll have to drill the 4 corners first with say a 1mm drill to under-cut the "corners". I'd center the drill right on each corner. It won't be a perfect shape, but it will fit on the shaft with 95% surface contact.

Once the corners are drilled.I'd cut mill a 10mm long with a 5mm end mill. This will give you the 5 mm radius on the ends. Then offset

0.5mm in both directions to widen the slot to 6mm. You'll need to stop at the ends to roughly match the arc at the ends.

If you want a perfect, as drawn shape, you'll have to hand file the corners.

Bruce

Amr wrote:

Reply to
sawdoc

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