Last cutting pass is above the stock

Hello, I have a simple 2D contour created in Fusion, with a -0.2mm from model bottom set. To ensure it cuts through.

When I simulate in Fusion it looks great, but when I run it, the last pass seems to run above the stock. It should be cutting the final depth.

Any idea why this is happening?


Can you share the Fusion file?

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Here it is, thanks for taking a look!

square (87.4 KB)

I think it might be doing the whole operation in the wrong place. I have zero’d twice to the top of the stock. As per the fusion file.

Is it possible, that the whole operation is being reversed? It seems to do the lowest pass first and goes up. All above the stock.

ok so i have a few observations :slight_smile: F360 can behave a bit wierd some times depending on how you set your stock up, so try this

first your stock is really small as in 15mm x 15mm .6mm thick? is this a pcb or something. is this meant to be like this ?


In your file your origin and drawing are odd (to me at least) and i know when i deviate from this F360 at times does not like it. i notice that your file you have aligned to the top left instead of object origin, and then i notice your drawing direction is reversed by this i mean (brace for paint awsomeness)

i normally have my drawings goign in the direction on the dotted arrow

i also notice when i edit your file that it seems like the extrude is behaving badly making it minus - yet f360 is clearly saying it is a plus so that is odd

so what i suggest is this to try and if it still behaves the same come back to us please

create a new file and redraw the shape so that it runs from the origin to the right (arrow number 2) them make your 0.0 bottom left as per arrow 1.

Instead of it being on the top of the stock if you do it to the bottom you can then zero your machine xy normally but for the Z if you do it to the surface of your spoilbord (bottom of model as per screenshot) it will always go through your stock without the need for that negative offset (make sure you do not put ofset in or it will cut your spoilboard)

Important note your stock hight must be correct or you will either AIR CUT or CRASH, for more info on how to do this see this post spoil board

let me know if that helps, i know other people may say popycock! but F360 is tempramental - or at least it is for me :slight_smile: if i stick to the above works a treat!

EDIT ** forgot to ask what post processor are you using to output the gcode? should be image


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I don’t disagree with anything @Sherpa said, but it doesn’t really explain what you’re seeing. Sounds like there might be a mechanical issue. When I generate gcode for your file, it looks good, cutting from top to bottom. The machine will do what the gcode tells it unless you have mechanical/electrical issues.
Can you share the gcode (.nc file) you ran?

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Thanks both for your replies! Very helpful.

I kept playing with it, and I think I found the issue, maybe someone can confirm this behaviour.

I didn’t have my end mill long enough so it was unable to cut through to the spoil board. So it seemed it reached the lowest it could and then cut the final pass higher up. Not sure why that would happen, but either way I’ve fixed it now.

Yes I’m cutting 0.3mm brass.

I also think because it’s 0.3mm I was not zeroing with enough accuracy. So it was air cutting above the stock in a few of my test.

Thanks again for the fast replies.
I will use a more standard stock setup next to try and rule out errors.

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