Automatic (semi) platform calibration checker

by eried, published

Automatic (semi) platform calibration checker by eried Aug 7, 2012


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In almost a year using a 3d printer, I have learned that platform calibration is probably the most important factor to get nice prints.

This "method" uses a digital depth meter, a webcam, a macro, a spreadsheet app and a OCR application to get a matrix of the current heights in the platform. My adjustment will be based on a primitive approach (almost by hand).


1) Print http://www.thingiverse.com/thing:14174 (or similar) for your digital gauge

2) Set a webcam (or better link your meter via serial port) to look into the meter screen, in this case with http://www.webcamlaboratory.com is easy to do an OCR and get the data (too bad that app is now exclusive for Intel learning pcs)

3) Use the attached macro in Vtask (or use your prefered macro app, or better direct link with the printer via serial). The macro should do this: http://screencast.com/t/6SduKMZ5Q

4) Use the attached excel and replace your values. Of course the "stress" deformations per screw are very dumb values I guessed by hand, no 2D interpolation or something fancy (I am not sure yet how the platform bends, so it maybe much harder than I guess, but I just wanted a quick test to help me)

5) Rinse and repeat! until the flatness on your platform is TOO DAMN HIGH!

PS: In my excel graph, height is dramatized (all values are less than 0,3 mm, so my platform is quite flat)

Here is a video :)

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Does your macros interface with the printer? It doesn't sound like it, so here's a suggestions: what if you told the printer to move to each corner/screw location, then home Z and read the "depth," record it, repeat for all screws. Then suggest amount of change per screw?

My platform is slightly bended in one side without screws :P I think I have to take it appart

Not sure why I pluralized "macros" and "suggestions".... DONT_KNOW

Well, the macro just interface with RepG. What you say is possible for the back screws but in the front the wooden bezel don't allow the platform to reach the 2 frontal ones.

Maybe with a smaller gauge, or replacing the exturder with the gauge what you say will be possible. I will try that soon! sounds like a great idea! I hope my platform isn't bended :D

This is a great approach. I think the same thing could be done with an analog gauge and a hough transform (instead of OCR)

in marlin, z_ajustment branch, you can enter things like your array for firmaware-based correction.

I guess this will work for rafted prints? otherwise what the firmware fixes? sounds very cool anyway!