Weird jog causes rest of cut to shift by width of the jog

[tjandt (Tim Jandt)]

Hello,
I’m working with VCarve Pro 11 and am experiencing a strange jog on one piece that then causes the rest of the cuts to be off by the jog amount. Here are the details:

Vcarve Pro 11
Shapeoko 3 XXL
Importing DXF file created in Visio into VCarve

The piece I’m working with is 24" x 31.75". I make multiple cuts that work just fine, then come to a piece on the far right of the work. The cutter seems to be going fine, then does this weird kind of jog, and the rest of the cut from that point forward is off by the width of the jog.

I’ve re-drawn the piece, thinking it may be a vector issue, but still have the same error. No issue with vector validator, and the node edit on it looks very clean. I have included a picture of the issue, and would really appreciate any help in resolving it. The object I am trying to cut is all straight lines, so I have no idea where the zig zag that I have in the red rectangle is coming from?

Thanks,
Tim

[WillAdams (William Adams (Carbide 3D))]

Are you cutting a slot just as narrow as the endmill?

Where possible avoid slotting and add geometry and cut as a pocket

Making vacuum hose adapters

While cutting up vacuum extension wands for this is expedient, it’s a bit problematic given that Shop Vac recently filed for bankruptcy, was bought at the last minute, and production hasn’t caught up. I need a receptacle for the Sweepy 2.0 dust fitting — one option would be to purchase one from Woodcraft, but Carbide 3D sells blocks of HDPE: which looks to be just barely big enough for things to fit. Measuring the hose fitting I get a diameter of ~63.5mm — offsetting that twice we arrive at…

and/or

Adding geometry to cut as a pocket with a finishing pass

One technique which is often suggested to avoid slotting is to add geometry around a part which one wishes to cut out and cut as a pocket down to tab depth — here’s one technique for that. In this case, the project is a bevel gauge which will be cut out of 0.0625" (~1.5mm) thick aluminum: [bevelgauge] Due to the narrowness of the angles, an 0.03125" endmill has to be used, so after importing and scaling the file (we will be cutting out one which is 3") we select the perimeter and offset it tw…

and consider leaving a roughing clearance and taking a finishing pass.

[Julien]

@tjandt

then come to a piece on the far right of the work.

Are you sure you did not reach the mechanical travel limit? That would easily explain losing steps (and therefore the offset for the rest of the job)
31.75" is close enough to the machinable area limit that this could easily happen

[tjandt (Tim Jandt)]

Does not seem to have met mechanical travel limit, as it made one cut at the right spot, then a weird jog after. When I initialize the machine, the spindle travels inches farther than the edge of my work piece as well.

[tjandt (Tim Jandt)]

Not quite sure what you mean. I’m not cutting slots. I am using the profile toolpath to cut around the outside of the pieces I am making.

I also noticed that in VCarve Pro 11, there are different post processors than there were in VCarve Desktop 10. In 10, the post processor was just Shapeoko (inch) (.gcode). In 11, I have Carbide Motion ATC (inches) (.nc) Looks like the set up for machine and post processor are really different in 11. Could that be it?

[WillAdams (William Adams (Carbide 3D))]

Is the toolpath as narrow as, or wider than the endmill?

If it is as narrow as the endmill, it’s a slotting cut.

[Julien]

@tjandt

Could that be it?

I very much doubt it would be the post-processor, but one easy way to check is to use a gcode preview tool to check if the generated gcode has this weird part in it. I like to use ncviewer.com

If the gcode previews correctly, then it is something mechanical. I can’t tell from your picture what the orientation is ? (which axis is X and which is Y). It’s probably either lost steps due to too aggressive cutting (i.e. what Will is referring too, slotting too deep) or a pulley slipping on the motor shaft (and then double check the setscrews on the axis that slips)