Drilling operation will gouge if retract hight < start depth

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herbk
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Re: Drilling operation will gouge if retract hight < start depth

Post by herbk »

Hi,
just to make sure...: we are talking about the retract of a Peck?

If yes, the drill should retract die user given distance from "where it is". Look at Chris's explanation.
Gruß Herbert
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Re: Drilling operation will gouge if retract hight < start depth

Post by IMback! »

herbk wrote: Mon Jul 29, 2019 6:29 am Hi,
just to make sure...: we are talking about the retract of a Peck?

If yes, the drill should retract die user given distance from "where it is". Look at Chris's explanation.
This is what i would expect also. Retract hight should be relative to the depth of the last peck cycle to allow 1mm retract chip breaking operation. Retract hight from non-peck holes, and final retract hight should simply be the safe hight, as the tool gets traveled to the next hole intimidate afterwards. Making the retract relative to the depth of the last peck is non-tivial though because the g83 caned cycle just dose not work like that. You can make g83 do what you, and i, want by having the entire operation run in g91 incremental mode, but this requires significant adjustment.
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Re: Drilling operation will gouge if retract hight < start depth

Post by GeneFC »

Whoa!

This discussion has gone completely off the rails.

Retract height is a well-defined quantity for *both* G81 and G83. We should not try to redefine G-code to fit some special cases.

As noted above the partial retraction during peck drilling is not supported by G83. If that is what is needed then it needs to be laboriously coded for each peck step.

I am fine with redefining the FreeCAD Path WB *default* for retract height, but please do not try to change the meaning.

Gene
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Re: Drilling operation will gouge if retract hight < start depth

Post by sliptonic »

There's no reason the UI controls and properties need to have a 1:1 correspondence to the Gcode parameter words in the canned cycle.

Of course we need to generate correct gcode but the UI should be whatever is most intutive.

My original intent was that the retract height property would store the relative distance that the peck cycle would retract. So a reasonable default value could be 1.0. That would result in a R word in the G83 line of StartDepth+1.0?

If the retract height property is to store an absolute value that corresponds to he R word, then the logic needs to be improved so that retract height can't be less than startdepth.
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Re: Drilling operation will gouge if retract hight < start depth

Post by sliptonic »

BTW, just a reminder that there's a handy tool for visualizing the pecks.

pecks.png
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IMback!
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Re: Drilling operation will gouge if retract hight < start depth

Post by IMback! »

see PR
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Re: Drilling operation will gouge if retract hight < start depth

Post by IMback! »

Some side notes:

I don't think PathGui.QuantitySpinBox should be in path, we should not be writing our won python bindings for core functionality.

I don't think every operation should implement the layout and update logic for the tool controller combobox, this should be its own pannel.

I don't like how python is used in path (gui, large code segments) i think python is ill suited and makes maintenance harder, but im probably going to be alone in this.
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Re: Drilling operation will gouge if retract hight < start depth

Post by IMback! »

mlampert wrote: Sun Jul 28, 2019 11:15 pm I would vote for the distance above start depth - that makes sense to me.
I prefere an absolute retract height, but am not bothered either way. The issue i have with this is am note sure how the ui should communicate to the user that this is suddenly an offset when everything else is absolute.
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Re: Drilling operation will gouge if retract hight < start depth

Post by RatonLaveur »

Maybe just change terminology between "full retract" and "peck retract"?
Alternatively an "interactive" diagram such as the one for tool definition?
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Re: Drilling operation will gouge if retract hight < start depth

Post by GeneFC »

Further and further into the ditches. :roll:

There are two significant mistakes being made in this discussion.

1) The drilling G-codes, G81, G82, and G83, do ***NOT*** drive the tool into the workpiece as a result of a direct 3-D motion to the start point. Instead, there is first a rapid Z-only movement to the retract height. THEN there is a rapid X-Y movement to the start position. The reference cited in the first post of this topic says exactly that. I have observed the same behavior in my shop.

Yes, if the retract height is too low there will be gouging. The solution to that problem is to set the correct retract height. Using the safe height as a default instead of a fixed 10 mm is a good idea. Removing the ability to set the retract height for plain drilling (G81) is a very bad idea.

2) The partial retract behavior mentioned by chrisb and herbk would be nice, but it simply does not exist. There is no such thing as a partial retract or a peck retract in ordinary G-code. It does not matter if one is using incremental or absolute coordinates. The canned cycles, G8x, don't care. They will continue to do the full retract in all cases.

If a partial retract is desired it will take some coding to made a "subroutine" type function to output a string of G0 and G1 codes.

The only thing needed for the immediate problem of gouging is to set a better default retract height.

Gene
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