Mountain Top missing

I have made two carvings in Carbide Create Pro using 3D rough and finish passes on an imported greyscale PNG file.

Then 3D rendering clearly shows the mountain top as well defined and all of the other contours showed up very well.

I was using a #201 .25" endmill with a .125" step over and .125" step down for rough, and a 0.03" step over for finish.

Any advice would be greatly appreciated.

Did you set zero at the bottom of your stock?

I zeroed it with my Bitzero from the top of the stock. I had no bit changes during the carve.

Did it cut the top or just ignore it?
Can you share the gcode?

It looks like the stock wasn’t thick enough for the entire model. Or if it should have been, maybe the model bottom wasn’t set at stock bottom. Either way, the carving did what it could but the top of the stock ended before the top of the model did.

Except he zeroed at the top.

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Did you measure the material to make sure it was as thick as you think it is? A 2" piece of lumber isn’t 2" thick…

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But even zeroing at the top, wouldn’t the model still “start” at the bottom and go up from there? I don’t really know CC, I use Vcarve and I’ve run into this using that. If the total model height is 1 1/2" and you set the bottom of the model at 1/2" meaning the stock needs to be at least 2". If the stock is actually 1 7/8", you measure from the top the bit will still go down as if the stock was 2". Or maybe I’m over thinking this

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Because he’s zeroing at the top, everything should be from that point down.
Assuming Gcode checks out…Maybe a workflow issue with zeroing or a mechanical issue that caused Z steps to be lost.

I don’t either, so maybe I’m missing something.

It looks like you’re using a square endmill — could you try again using a ball-nose?

Which version of Carbide Create are you using? I ask because, I think (uh-oh), the feature that shows modeled components that are above the surface of your stock in bright red wasn’t added until a few versions ago… it may just be the modeled component is slightly taller than the stock thickness you set and your version of CC isn’t notifying you of it.

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It cut the top off in the first pass. I was expecting it to go around on the rough pass. I was very surprised when it went clean over it.

jo mary2.nc (2.8 MB)

Since several people have asked, I will answer generically. It is my understanding that by zeroing that the top, all dimensions are done in the negative. The same direction as the cut. So, if my lumber were not as thick as I had set it to, the cut would have started at the same point with the lowest cuts going down into my spoilboard,

Alternatively, if it were a thickness issue, and I were zeroed from the bottom, it would have resulted in a phantom pass going over where the board was supposed to have been.

Everything cut exactly like it should have with the final cut being just as I expected it, with the exception of the mountain top. Which was cut clean off.

I should also mention that this was my second attempt, carving the same basic image at 7x11 rather than this one at 11x17 on the same thickness board, and it resulted in the same smooth top. So, I am doubly perplexed.

I’m currently running build 443. The simulation showed that the mountain top was not to be cut during the rough pass, and to be done in the finished pass. Unfortunately the rough pass did cut over it.

That is correct. I could if I had one. It is on my list of bits to order. I am curious as to how much cleaner a ball nose will cut. I was thinking, aside from the topless mountain, a little sanding would smooth this right out.

Here is a picture to show that the top was cut down below the surface of the material. on the right is where the cut didn’t quite reach the edge of my board, leaving the entire thickness.

I am really perplexed by this. The simulation shows that should be there, the rest of the topography cut as expected.

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How big is that flat area, in diameter?

not very, about the size of my finger tip.

Ok, it’s in the gcode then.
There is a peak about a cm in diameter that has a .002mm difference in Z across the top.

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