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May 25, 2018, 07:46:51 am


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Author Topic: shortcut which damaged the part - unsafe crossing  (Read 473 times)
C-Sharp
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« on: May 02, 2018, 17:22:52 pm »

I've come across a simple milling operation, in which a profile the outside of a circle. It needs multiple passes to go to the full depth.
Strangely enough, when going to the starting point of the last pass, it doesn't go to the safe height. It moves in a straight line from A to B (see pictures), without going to the safe height.

I didn't realize this in time, so my part got damaged.

Does anyone know what happens here and how I can avoid it?

* unsafe_crossing.cb (3.86 KB - downloaded 15 times.)

* unsafe_crossing.PNG (14.75 KB, 292x548 - viewed 45 times.)

* unsafe_crossing_milling_program.PNG (4.77 KB, 363x349 - viewed 38 times.)
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dh42
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« Reply #1 on: May 02, 2018, 18:27:15 pm »

Hello,

change Max crossover distance to 0.6 and the rapid to clearance come back Wink

It's because distance between A and B (on XY plane) is ~ equal to 5.6mm

The distance that triggers a move to clearance is defined by the formula: Max crossover distance * tool diameter.

in your case MCD = 0.7 ; TD = 8 > 0.7 * 8 = 5.6mm too, so no move to clearance is performed.


Quote
Max Crossover Distance    

Maximum distance as a fraction (0-1) of the tool diameter to cut in horizontal transitions.

If the distance to the next toolpath exceeds MaxCrossoverDistance, a retract, rapid and plunge to the next position, via the clearance plane, is inserted.

Another useful features in spiral lead-in is to set Spiral angle to 0 ; in this case CB will calculate a continuous helix with a pitch = depth increment
http://www.cambam.info/doc/dw/0.9.8/cam/LeadMoves.htm

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David
« Last Edit: May 02, 2018, 18:42:59 pm by dh42 » Logged
C-Sharp
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« Reply #2 on: May 04, 2018, 18:49:25 pm »

David,

You have no idea how much time you've just saved me with that last piece of advice. Thank you very very much!
I was wondering how to get rid of all those redundant rapids to safe height I'm constantly getting when milling to depth using several passes. This is exactly what I needed!

You sir have deserved a great weekend.
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