Path Rule "On lead in"

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David_Lelen01
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Path Rule "On lead in"

Post by David_Lelen01 » Tue Aug 06, 2019 7:02 pm

When a path rule on lead in is created, the post processor now seems to ignore whatever code is under a function OnOffsetLeft or OnOffsetRight.

I need some way for my machine to know which offset direction sheetcam is specifying. It either uses G141 for offset Left or G142 for offset right. If i put the start sequence under OnPenDown, the offset is not captured yet. If is use the OnOffsetLeft then for some reason it is getting ignored when path rules are active.

Is there a better way or different function to do this?
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Les Newell
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Re: Path Rule "On lead in"

Post by Les Newell » Tue Aug 06, 2019 8:00 pm

SheetCam generates compensated tool paths. It does the offsetting rather than relying on the control to do the offsetting. It looks like you are trying to make your control do the offsetting.

David_Lelen01
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Re: Path Rule "On lead in"

Post by David_Lelen01 » Wed Aug 07, 2019 12:32 pm

That appears to be my problem. The waterjet machine automatically compensates for the kerf width, but it does need to know whether it is supposed to be an inside offset or outside offset. There is no option for it to not compensate that i am aware of. I am trying to get a list of G/M codes for this machine from the manufacturer, but no success yet.

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Les Newell
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Re: Path Rule "On lead in"

Post by Les Newell » Wed Aug 07, 2019 3:38 pm

Does it allow you to define a kerf width of 0 on the machine? That way any offsets it applies will have no effect.

David_Lelen01
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Re: Path Rule "On lead in"

Post by David_Lelen01 » Wed Aug 07, 2019 8:59 pm

No, it doesnt appear to have a way to change it. There seems to be only one nozzle available for this machine and it is hard coded in. It does appear that i can tell it to use tool 0 and it ignores the offset, so that is a possibility.

David_Lelen01
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Re: Path Rule "On lead in"

Post by David_Lelen01 » Wed Aug 21, 2019 7:57 pm

Les,
I was able to set the machine to tool 0 and the cut paths worked out perfectly with sheetcam handling the offsets. Now the problem with that becomes the machine still needs to know if it is a left or right offset because the machine tilts the head slightly to compensate for cut taper. The direction of this taper adjustment changes with the offset direction.

So is this possible to do in SheetCAM or is the tilt another parameter i would best turn off in the machine and just live with the taper?

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Les Newell
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Re: Path Rule "On lead in"

Post by Les Newell » Fri Aug 23, 2019 1:51 pm

SheetCam doesn't officially support offsetting but there are functions OnOffsetLeft(), OnOffsetRight() and OnOffsetNone() that are called as required. I cannot guarantee that they are correct 100% of the time, which is why they aren't documented.

David_Lelen01
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Re: Path Rule "On lead in"

Post by David_Lelen01 » Fri Aug 23, 2019 6:52 pm

Those functions, as far as i can tell work perfectly as long as a path rule is not used. When using path rules, the functions are ignored for some reason. As a work around, i will have to be sure the cut direction works out to put the offset on whichever side i program the post to write to the code.

I am just trying to make things as dummy proof and robust as possible so others at my company will be able to use it without generating a toolpath that renders the part unusable before they realize it.

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Les Newell
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Re: Path Rule "On lead in"

Post by Les Newell » Sat Aug 24, 2019 4:33 pm

I'm surprised rules affect the offset functions. It is a long time since I last looked at these though.

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