Bug with drilling translate.

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freman
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Re: Bug with drilling translate.

Post by freman »

You did not agree with me. The simulator serves a very useful purpose.
OK Gene, I was not saying the sim was totally useless but it still sucks ;) That comment was not supposed to be a detailed technical appraisal.

@tigermm, thanks for the file, the four hole would have done as well but I want to see exactly what you are seeing not a verbal description. I wanted to see how you were getting z=0.

The file you provided above does not seem to have a drilling operation in it. Could you please provide a file showing the issue you are reporting , so that I can try to reproduce and debug it?

G81 and G83 get a retraction parameter R which seems to be set by Start Depth . If I add a drill op to your model , without drill cycle treatment in grbl-post, it still fails to lift to safe/clearance height between holes. It seems the clearance move happens AFTER the G0 XY move !

Code: Select all

M3 S20000.0
(Finish operation: TC: Default Tool)
(Begin operation: Drilling)
(Path: Drilling)
(Drilling)
(Begin Drilling)
G0 Z10.000
G90
G99
G0 X42.500 Y42.500
G0 Z5.000
G81 X42.500 Y42.500 Z-20.000 F1000.000 R0.000
G0 X42.500 Y157.500
G0 Z5.000
G81 X42.500 Y157.500 Z-20.000 F1000.000 R0.000
with no post-proc the clearance is there, in the wrong place.

Code: Select all

(Begin Drilling)
G0 Z10.000
G90
G99
G0 X42.500 Y42.500
G0 Z5.000
G81 X42.500 Y42.500 Z-20.000 F1000.000 R0.000
G0 X42.500 Y157.500
G0 Z5.000
G81 X42.500 Y157.500 Z-20.000 F1000.000 R0.000
grbl-post isn't eating it . AFAIKT this is not a post-processor issue.
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freman
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Re: Bug with drilling translate.

Post by freman »

It seems that this comes back to inappropriate action on grouped holes which was discussed and then dropped inconclusively about a year ago. Some consideration could be given to whether Start Depth should be identical to R parameter, which is the retraction height , not the start of drilling.

@tigermm, I suggest as a work around you set Start Depth to something clear of the surface instead of zero. This will add a finite R value to the drilling commands and avoid tool contact.
tigermm
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Re: Bug with drilling translate.

Post by tigermm »

Thanks Freman.
I'll set start depth a little higher and see what happens.
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sliptonic
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Re: Bug with drilling translate.

Post by sliptonic »

The problem is probably that you have the retract mode set to G99 in the operation. This causes retraction to the R word which the translation respects. Setting G98 causes retraction to the previous Z height.
2022-04-13_10-38.png
2022-04-13_10-38.png (113.8 KiB) Viewed 940 times
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freman
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Re: Bug with drilling translate.

Post by freman »

Thanks, I had not seen that option tucked away in the treeview.

https://www.cnccookbook.com/g98-g-code- ... ate-modes/
runryder
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Re: Bug with drilling translate.

Post by runryder »

This was very helpful because on G99 my drill bit dragged across my material. The bit is OK. G98 fix my issue

thanks
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freman
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Re: Bug with drilling translate.

Post by freman »

Hi,
so I guess you set tract height R0 which with G99 drags the tip across the work.

I use negative R height ( assuming z=0 is the top of stock ) when peck drilling to prevent the drill bit exiting and re-entering the hole and enlarging it. I would guess I'm not the first person to think of that.

This means you are likely to break the tool if it drags to next hole at neg. Z.

Particularly in view of the obscurity of this setting wouldn't it be better to default to the safer (but slower) G98 until the user discovers this tweak?
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