[TarHeelTom]

Using EMC2 on an ancient Bridgeport. I could easily do this in a CAD-CAM program, but have been hand programming most of my simpler parts to get better acquainted with Gcode.

Need to cut a hexagonal pocket, with fairly sharp corners, 3/4" deep in a piece of 1" thick cr steel.

For the corners, I'll start by just drilling a hole at each corner to give room for the corner of the hex block which needs to slip or fall into this pocket. Simple operation, which I can handle easily.

Then I thought I'd just run six straight lines with G01 from corner to corner, then step in a bit, and repeat until I've got the corners of the straight lines inside the diameter of a circle which is smaller than the distance between the straight sides, then run a G2 operation to get to the center of the hex.

Then return to the starting point, lower the Z a few thousands (perhaps 0.020") and repeat.


I've got available 3/8" diameter carbide end mills and one 1" diameter end mill.

Is this a fairly efficient way to go about this? Or should I cut the circular portion of the pocket with the 1" end mill first, then switch to the 3/8" end mill to straighten out the sides?

I have only an Armstrong tool changer available now, and probably for the forseeable future.

Any suggestions?

Thanks

Tom

[yellowcard]

The second method you brought up would be my method of choice.

[TarHeelTom]

Thanks, Yc

[BobWarfield]

Interpolate the inscribed circle first. That's very quick and easy and can be run faster than following the outline of the hexagon. You could even use the hole interpolation wizard in G-Wizard Editor:

GWCC: Happily Interpolating Holes with CNC Conversational Programming! « CNCCookbook CNC Blog CNCCookbook CNC Blog

Once you have a hole interpolated with the 1", swap tools and make one roughing pass and then one finish pass. Shouldn't be that much material to remove after the interpolated hole is cut, so maybe you wouldn't even need 2 passes, but let's just be conservative.

Should be pretty easy to write that code.

Best,

BW