confused drilling path

[freman]

Hi,

I just pulled a fresh copy of master a couple of days back and knocked up a simple plate with four holes in it.

I added a drill path which did not select "peck" option.

When I look at the output I'm getting an air cut G80 down to stock; G0 to safe-height, then a G81cutting the same hole in the air hole before actually cutting the metal.

This is obviously a gross waste of machine time and seems rather confused. Why is it mixing G80 and G81 to get this job done?

This does not seem right. What is going on ?

Thanks.

OS: Fedora 34 (Thirty Four) (LXQt//usr/share/xsessions/lxqt)
Word size of FreeCAD: 64-bit
Version: 0.20.26155 (Git)
Build type: Release
Branch: master
Hash: 0926a4148bcff11249fd4f56bc30256102ffe105
Python version: 3.9.7
Qt version: 5.15.2
Coin version: 4.0.0a
OCC version: 7.5.0
Locale: English/United Kingdom (en_GB)

[GeneFC]

This does not seem right. What is going on ?

Drilling used to work perfectly. I used it for thousands of holes.

A little more than two years ago someone had a problem when trying to drill a bunch of holes on a non-planar surface, all while using a single G81 operation. Broken tools and damaged material.

The solution was to kill the canned operation (G81) after every hole by adding a G80 cancel command. Extra hops up to the Clearance height were also added.

I argued quite strenuously against this silliness, but I lost.

I now have a modified postprocessor that removes all G80 commands. They are never really needed, since any motion command, such as G1, will cancel the G81 canned operation.

Gene

[freman]

Thanks Gene. So it's a case of broke by design

I recall a discussion about a year about safe ht vs clearance ht, which seems to have the same root problem of not doing things the right for some distorted logic. I think it fizzled out and it just got dropped.

Could you post you post processor or PM me? That could save me some time writing it. This just taking a stupid amount of time cutting air.

Thanks for confirming it was not just me looking at it backwards.

[GeneFC]

Sorry, I did not remember my final solution correctly. I changed the PathDrilling.py instead of the postprocessor.

I removed:

Code: Select all

     # Cancel canned drilling cycle
            self.commandlist.append(Path.Command('G80'))
            self.commandlist.append(Path.Command('G0', {'Z': obj.SafeHeight.Value}))

I tried several things and ended up with this solution. I have not needed to drill a large number of holes lately so I forgot what I did.

Gene

[freman]

Brilliant , that saved me lots of time. Since I'm building from src anyway, that's just a tweek I have to put in each time.
Thx.

[GeneFC]

Just make sure you check that the resulting path is sensible.

Gene

[freman]

OK, I'll only say it was your fault if it goes badly wrong and I need someone else to blame