Engraving toolpath issue - Engraving glass with drag bit

I am having difficulty understanding where these odd straight diagnonal lines in my engraving are coming from. I would appreciate some enlightenment.

The image shows the lines extending from the bottom left of the wing across the thorax and just into the right wing segment.

Here are the .nc and the c2d files.
Butterfly outline.c2d (574.6 KB)
butterfly outline.nc (167.7 KB)

Screen captures showing the file and setup in Carbide Create.

.svg image that I want to engrave into glass.

Butterfly1Black

Increase retract height to be more than 1mm

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Thanks Will. would you tell me the reason that these diagnoal lines are appearing?
Is the solution that any Z retract height above 1mm will work or do I have to as high as 2mm?

You need to have retract high enough that the spring loaded Endmills doesn’t drag — don’t the correspond to rapid moves?

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Look at a simulation and you will most likely see the same lines as the lines of the path of the bit in the simulation.

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I have just changed the retract height to 15mm because the random movements are very likely to hit the gator clamps. I dont see that the rapid moves are essential in this pattern, whe you look at the items being engraved in the lower left hand corner. I have made a short video so that you can see the issue.

https://youtu.be/wSftiSnYrRc

Following @gdon_2003’s excellent suggestion (thanks Guy), I have taken the file into NC viewer. This is the screen capture.

I have given up on the engraving toolpath. It has now cost me two pieces of specially cut float glass. I have no interest in ruining another piece. Even with a retract height set to 16mm, the software let it strafe across the workpiece as if no retract height was set. I wonder if the engrave toolpath is doing the right thing.

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For the life of me I can’t understand why the code picture shows it sending the tool outside of the butterfly so many times like it plans to draw 1 feature retract and go a few inches outside the carving only to return to add another feature then repeat the retract and extra travel or am I not looking at this image correctly?

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Absolutely correctly, Donovan. There can be no need for the engraving toolpath to behave like this. I am unwilling to waste any more resources on tracing something that has no logic to it. This kind of irrationality is very frustrating when there is no purpose to it.

After making the change to the retract height on @WillAdams suggestion (as far as I can tell, 1mm should have been enough. This curious scraping behaviour required 3mm retract height to clear the issue because of the heavily sprung MC Etcher bit. As soon as I saw the strafing behaviour about to crash the bit into my clamps, I called a halt and upped the retract height to 16mm. CM behaved as if the retract height was zero!

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You’re not using a BitZero/BitSetter combination, are you Jeff? The lack of Z height seems very similar to my own issues with deeper than expected cuts!

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Diamond tip engravers can’t be used with BitZero as they are not conductive.

The spring could seriously compromise tool length measurements with BitSetter. I have a rigid sleeve I place on my engraving tools to prevent compression when using the Bitsetter. It may be easier to switch off the Bitsetter and run engraving as a dedicated file.

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I thought diamonds conduct electricity, or are they “not-diamonds”?

No Peter, good thought but I did everything manually.Touch off and zeroing X,Y and Z. Whether this is one more Z height random issue or it is related to the generation of engraving toolpaths is not easy to discern. I am clear that after six hours of posting the issue, with the relevant c2d file, the appropriate .nc file, a screen shot demonstrating the .nc viewer file output; along with a short video showing the unprogrammed behaviour in a manner that I would call comprehensive… that Carbide 3D has been silent.

I will send the link to this thread to support and see what they can make of it. With the number of Z height issues to which I have seen several referrals of late in the forum, I am starting to consider that something is flaky in the software handling of Z height commands.

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Excellent point. (pardon the pun) :grin:

I don’t like the BitSetter initial hit and felt that could damage the diamond. The spring compresssion is another issue. It seems harder to compress than my RDZ tool, which can be compressed by easily grasping the mount and pushing inwards. That cannot be done with MC Etcher.

I had already concluded that running the file manually was the best option and I separated the file into five separate toolpaths. I had no idea how long the file would take to run and wanted some control over the process whithout having to pause the machine for a long while.

I think the video is revealing. This cannot be correct behaviour no matter what the file looks like. I saved my MC Etcher tool from being crashed into my stainless clamps. The software not obeying the set retract height is a more serious issue. With so many recent Z height issues being reported, I suggest that it is long overdue for the developer to put this bug to bed.

Thread link mailed to support@carbide3d.com in the hope that this issue will be addressed.

[Material Properties of Diamond]

TLDR: Diamond is a good electrical insulator, having a resistivity of 100 GΩ⋅m to 1 EΩ⋅m.

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Jeff, When I load the .nc you posted in ncviewer I see what you see.

But when I loaded the .c2d file you posted and saved the gcode with CC it looks quite a bit different in ncviewer.

Maybe an issue within CC? I’m using the new beta, build 605

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Hi Ed. Thanks you very much for this information. The issue appears to be solved when I run the software version beta 606 as a simulation. You are a gentleman. Thank you very much.

The screen capture from beta 606 shows the file looking as expected. I had set the retract height to 16mm because I did not want my clamps to smash the tool if it was unexpectedly launched into them.

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Using the beta 606 of CC; the software has produced a much better result.

Lots of potential now for illuminating the glass from the side, adding a wooden frame and standing the whole thing on a base. I now am interested in seeing what I can do with coloured glass, frosted glass and assembling panels of pieces. Lots of artistic potential here.

Feed rate was 400mm per minute and depth of engraving was set at 0.050mm. Touch off manually and no BitZero or Bitsetter involvement. Piece required about 1 hour and 45 minutes to cut entirely. I bathed the glass in CT 90 cutting and tapping fluid which stayed where it was put because it is reasonably viscous.

The retract height was left at 16mm because I was unsure whether CC would try and break the bit by lanching it across the face of the glass, into a clamp.

I would like to thank @Ed.E for his welcome assistance in solving this issue for me. Thank you Ed. I very much appreciated your invaluable help. :+1:

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Well would you look at that?!?

Looks great! I’ve been following closely as engraving seems like a fun endeavor. Thanks for taking the hits, Jeff. I’m probably going to pick up an RDZ given the unavailability of C3Ds MC Etchers.

Aren’t the MC Etchers adjustable? Which version of CC were you running with issues? I see you’re running CC Pro. I’m way behind on beta updates.