Finally got around to trying out the sample project with the CNC head! First thing I did was let it home itself and move to the start position. Snapped the bit off dramatically! Lesson learned!
Several days later, after receiving new bits from Amazon, I tried again! After loading the project in Luban, processing it per the instructions and sending it to the printer, I manually positioned the head in the starting position, acquired the correct starting point using the calibration paper and running the perimeter to ensure I was within the bounds of the provided slab of acrylic. Then I started the job and watched the first few levels cut, happily tending to the waste with my shop-vac. After a few levels of cutting, I decided to let it work and stopped watching. Yeah, maybe not such a great idea. I returned to find the machine had carved the pieces of the project into unrecognizable (and unusable!) scrap, and had continued to carve several millimeters into the bed. Kinda seems like providing a sample project and step by step instructions wasn’t so great, when these are the results.
Now I’m back to the drawing board, minus an acrylic slab to make something cool from. I would welcome an actual tutorial if anyone has a suggestion, as the sample projects don’t really teach anything - especially when they go to shit.
But, hey! What a neat way to introduce someone to CNC! Thanks, Snapmaker!
I feel your pain. I knew absolutely nothing about CNC and it is clear that Fusion 360 has a quite steep learning curve. I had imagine that getting the drawing right and plugging in the dimensions would be sufficient to start the cutter doing its thing. I guess the theory of that is ok but the practice is different. I found some of the settings in Luban to be somewhat opaque to me initially and the settings required seemed to be difficult to follow. In an ideal world I would have been sent a file by Snapmaker that was a known dimension and it would have come with an explanation of the settings required to duplicate the file. This would have shortened the learning curve and the messing around with trial and error to discover simple things, like the bit size affecting the final result size, which may seem obvious but not when you don’t understand the processes required to run a CNC machine.
My first project (SM1) was to cut a 10mm deep x 40mm square hole in a solid piece of maple. Because I had used the method of saving the generated G-code file to a USB stick when laser etching, I felt that CNC carving would be usable with that method too. I was wrong because the computer connection permits you to run operations such as the ‘run boundary’ command, which could not be done from the USB stick.
Another problem that was caused by me was not understanding that the dimensions of the cutting bit would be added to the dimension of the shape to be carved. This meant that my first attempt at cutting a 40mm square that was 10mm deep ended up with me carving a 43mm square that was 10 mm deep. I feel that the Luban software should compensate for this by noting the size of the shape that has to be carved and adjusting the head to produce that specified size once the software has the bit size input into the equation.
When first using CNC carving, I noted that the cutting operation took a very long time (10 hours for my 43mm 10mm deep square) to complete. In one way that was good because it prevented me from damaging the end mill bit by forcing it through some very dense wood. What i had failed to recognise was that the movement in the ‘X’ axis was not exactly half of the bit diameter so that it was moving just one tenth of a millimetre in the ‘X’ direction with each pass. The CNC carving tool was doing exactly the same 0.1mm plunge in the ‘Z’ axis so that it carved beautifully smoothly but very slowly (and incredibly noisily). As far as I can tell, the carving speed is also influenced by setting the work speed to get the bit to move a bit quicker in the ‘Y’ axis.
I have lots more work to do to get up to speed with the use of Luban because I want to be able to use the software easily to achieve the projects I have in my mind. Luban does not permit easy visualisation of a project and I hope to be able to utilise something like the web based Easel (Inventables) for its very visual approach. I am looking at other software and have extended my examination of other software methods including CURA & Inkscape, to opening the G-Code file and seeing what is required to edit it directly so that the machine follows my instructions closely.
I am just about to produce a surface clamping jig, specific to the work I want to do with it and it is going to be made from American walnut. I hope to be able to carve it and drill it with a lot more understanding of the process now. I am also making a new T6 6061 aluminium table because the current model supplied does not facilitate clamping from many different points and the clamps were soft and bent under moderate clamping forces. Both projects should be completed by the end of this week. I will keep the forum posted.