Wanted: Subroutine to Mill a Deep Slot...

18 Jun 2015 02:05 #59919 by lerman
I need a routine to mill a deep slot the width of the cutter. By deep I mean that it should ramp down the length of the slot, going back and forth until it is at the required depth. There are (at least) two cases. In the first case, the depth per pass is limited by the ramp angle. In the second, the depth is limited by how much one can cut in a single pass. The slot should have a flat bottom when it is completed.

Arguments to the subroutine should be:
startX, startY
endX, endY
startZ, endZ (convention is that making Z more negative increases the depth of the hole)

The routine should assume that the spindle is already running at the appropriate speed for the cutter diameter, material, and machine.

On startup, the spindle should rapid from the present position to startX, startY. It should then rapid to startZ. On completion, the spindle should retract to the startZ.

I see two possible strategies -- and I don't know enough to tell which might be better.

The first -- which I'll call boustrophedon -- ramps in one direction, then turns around and ramps in the other direction. This gets complicated in the case where the maxCutPerPass is the limiting factor in the number of passes. Also, since the return pass is cutting against a ramp in the opposite direction, the rampAngle should be divided by two.

The second -- which I'll call typewriter -- ramps in one direction, then returns at a constant depth and repeats.

My inclination is to go with the typewriter algorithm.

At any rate, the question is:
Does anyone have such a routine that I might beg, borrow, or steal?



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18 Jun 2015 13:52 #59931 by ArcEye

I don't know if you will get any takers.

Rather sounds as if you are trying to cut a slot with an end mill instead of a slot cutter and trying to find a way of doing all the cutting with the side of the mill.

It would cause a lot of wear at the end of the mill and be considerably slower than a proper 2 flute slot cutting mill.


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18 Jun 2015 18:10 - 18 Jun 2015 18:15 #59933 by Rick G
Last edit: 18 Jun 2015 18:15 by Rick G.

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19 Jun 2015 02:58 #59964 by lerman
Thank you to both of the people who responded.

I didn't know that there is a special type of end mill made for slotting.

At any rate, I wrote the code and cut the part -- see the attached.

There are two slots in the part:
The long slot is 3/8 inches wide.
The short slot is 1/2 inch wide.
The axis has been drilled with a letter Q drill and tapped 3/8-24 at one end.

Thanks again.

[Well -- I tried attaching the file (twice) and each time got a fatal server error.]


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