X/Y dimensional accuracy

Hi Folks, Trying to identify options for improving the dimensional accuracy of printed parts on my vc3.0. I'm printing some test squares and finding the following: modeled x-y vs actual x-y 20 x 10 -> 19.89 x 9.93 30 x 10 -> 29.83 x 9.95 50 x 10 -> 49.73 x 9.93 80 x 10 -> 79.66 x 9.93 40 x 40 -> 39.70 x 39.71 Short of scaling every part in x & y in the slicer, is there a more universal fix that can be applied? Thinking about tweaking stepper rotation_distance for x & y steppers but want to open some discussion on it to see what others think might be a solution. I have another printer that results in much more accurate sizes without scaling in the slicer so I feel like this can be done, just not sure what the right approach would be.
7 Replies
ptegler
ptegler2y ago
do search for skew compensation . there are prints you make, measure them and set offsets in printer.cffg
sherbs
sherbs2y ago
I've done this. This is not a skew problem.
blacksmithforlife
The fact that even though you change the X, the error is about the same each time suggests it is a slicing thing. If it was rotation issue it should scale proportionally
ptegler
ptegler2y ago
As blacksmithforlife just stated ,was my reason for stating skew correction. It's 'supposed' to be a ratio size correction, but I've found it seems to work better as a sizing correction. Looking at the numbers you posted shrebs, skew fixed it for me. Then again, i have to ask.... is this the same for ALL filaments you print or just one particular filament?
sherbs
sherbs2y ago
The error is not the same - it seems to increase as the dimension increases. As of now, I'm only testing with various brands/colors of pla... I can try other plastics at some point but don't want to introduce too many variables I did have some success tweaking stepper rotation distance... Going from 40 to 39.85 for the x & y steppers has me at 79.97mm on an 80mm dimension and 9.99 on a 10mm dimension I'll try skew also... But I'm not quite sure why skew would fix it when there is nothing telling skew that my AD measurement of 79.66mm should really be 80mm...
ptegler
ptegler2y ago
how tight are your belts? too tight (stretched) will move less for a given rotation distance.
sherbs
sherbs2y ago
peak tension at 1.75x10^6... x @74.2hz, y @ 49.4hz... this is on a 300... I think those are reasonable - or at least not indicative of belts being stretched...
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