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PixelCNC: CAM For Artists

CAM software developed by artists for artists to create unique and original works on a 3-axis CNC router or mill. · By Deftware

Random crashes while calculating operations

A topic by fordytes created May 05, 2021 Views: 115 Replies: 9
Viewing posts 1 to 7


I am looking for the right software to carve 3d topographic map projects with my CNC, and am testing PixelCNC v1.46a (trial).

After having imported a PNG with height data as a raster layer, I created a tool and then an operation using that tool. The software randomly crashes during the calculation of the operation, typically after a few seconds. 

The PNG is not particulary large (276 kB). Sometimes the first operation succeeds, but then it still crashes on the second or third operation. The operations I experimented with were all parallel carvings.

The logs typically end with ‘r_shaderuniformfloat: INVALID OPERATION’, if that helps. They occur frequently in each log.

Although PixelCNC looks promising and, based on what I've seen, would probably be my preferred CAM software choice, random crashes like these would make the software unworkable for me … quick feedback would be appreciated!

NB: I also tested 1.45a, which crashes as well on the same test, although it typically takes a bit longer.


Hi there, thanks for checking out PixelCNC :)

Could you paste your log file to and reply with the link that it generates so I can take a look?

It sounds like it might be a graphics hardware compatibility issue, but we may be able to adjust some things and get it running properly.


Hi Charlie,

Here is the link:

Let me know if you need any additional information on the hardware. Thanks for having a look at it!


Developer (2 edits)

After looking at your log file there's an error when compiling a graphics shader. I'll figure out a fix and have something for you to try out ASAP :)

EDIT: In the meantime I'd suggest trying updating your drivers as there may be an issue with the older version you're currently running that's causing problems too:

Hi Charlie,

Thanks for having a look at the issue! I've updated the graphics drivers already, but that doesn't seem to affect the issue. Looking forward very much to your fix :-)

Meanwhile, if there's any setting I could try or feature I can disable to circumvent the issue for now, let me know!


Developer (2 edits)

Alright, you can download a custom build here:

Go ahead and place the EXE in your existing PixelCNC folder and run it instead of the existing "PixelCNC Trial.exe" file.

There's no guarantee that it will solve the problem but I made some changes that might fix the issue you're seeing. I also included some extra information output to the log file during startup that might help narrow things down, worst-case scenario, so if you're still seeing the INVALID OPERATION in the log file (or the console, just press the tilde '~' key to see the log output while in PixelCNC) then go ahead and pastebin the log file it produced so I can take another look.


EDIT: I did some more digging and I think that this will solve the issue you were seeing! There's an issue with Intel's shader compiler that prevents it from supporting a certain math operation and the custom build above removes it.

EDIT2: If everything works for you as intended I'll get a public v1.47a hotfix update out today.

Hi Charlie,

Thanks for looking into the issue! I tried with the 1.47a build (placed the EXE in the existing 1.46a distribution as suggested), but unfortunately still got a crash using the same scenario, at the same moment, when the toolpath is being computed and shown.

Here is the new log: PixelCNC 1.47 test -

I hope this helps ! Let me know if you need any additional information.


Developer (1 edit)

Ah, it looks like your cut depth is set very very tiny, which is OK for horizontal finishing passes (i.e. horizontal milling operation with a cut stepover of zero) but for a parallel carving operation you'll want something more substantial. It looks like it's overflowing the Intel graphics  chipset with too many cutpath move geometry and crashing it. Try a larger cut depth. If your cutter and machine are rigid enough you should be able to use the entire flute length of your cutter for your cutting depth. For a 1.5mm diameter cutter I would use at least half of the flute length as a cutting depth here.

Another strategy is to use a roughing pass with a larger cutter that has a Leave Stock of a millimeter or two, a stepover about 30-40% of the cutter's diameter, and then come in with a parallel carving operation and the smaller tool for finishing - and you can set your cutting depth to the full depth of the project's canvas (or at least the cutter's flute length).



Hi Charlie,

Thanks for your feedback! My parameters were indeed too small, my mistake. I’m new to CNC and getting a good understanding of all settings is part of the learning process, I guess. I’ve been experimenting yesterday, and once I started to get a feeling for the reasonable range of each parameter, the software didn’t crash anymore.

It would have been helpful though if PixelCNC would show a warning when you try to create a path that is of unreasonable length, rather than crashing (even though it might be a graphics driver error in the first place). Especially when you’re still working with the trial version and can’t save your project, it is quite frustrating having to start over and over again …

The crashes made me even hesitate whether PixelCNC would be mature enough to spend my money on, but in the end your swift support and help convinced me :-) I’ve bough the full version yesterday, so I hope to start carving some nice projects in the coming weeks … 

Thanks for you help, keep up the good work!


Developer (1 edit)

Glad to hear it, and thanks for the sale :)

I figure that the best I can do as an independent developer is provide top-notch support for users, especially while I'm still working on producing learning materials - tutorials and walkthroughs that explain everything. I'm just about to release the v1.48a update, which incorporates some fixes, including the one for the INVALID OPERATION error you were seeing in the log file. PixelCNC should let you know that an update is available the next time you launch it after I've pushed the updates to the web.

I'll be sending out a customer-wide email about tutorial videos that are released as I put them up, so keep an eye out for those.

In the meantime feel free to post any questions, even if they're only CNC related and not PixelCNC-specific, or provide any feedback you may have on the software, however big or small. A number of PixelCNC's features are the direct result of user suggestions.

Share your projects here on the forum for others to see! I just did one the other day that I should post, a V-carving on an ebony-stained board with gold-painted cuts. It came out really nice.


EDIT: I did fix the crash that occurs if a user creates an operation that produces too many cutpaths, right now it just outputs to the logfile that the toolpath is being overflowed with cuts. It's a bit of a placeholder that will prevent PixelCNC from crashing for now. I will add in a prompt soon that warns users that their parameters are creating excessive numbers of cuts for v1.49a.