Stepper Calibration Indicator Mount Universal (FreeCAD)

thingiverse

Have you calibrated your stepper motors for accurate parts? Well get ready to do it again, the proper way this time. Nearly everyone online is passing on terrible information about calibrating steps-per-mm for XYZ based on cubes or calibration prints. Think about this for a second, would you think a machinist would zero out a tool based off of a machined part, of course not, so why would you do that on a printer? When you calibrate based on printed parts you waste time and filament. Not to mention that different filaments shrink at different amounts and you don't want that factored into your calibration. Most indicators measure down to .01mm. This is good enough for general machine shops so this is good enough for our printers. You've probably seen mounts for indicators for every printer that exists and those are great for bed leveling. But for some reason everyone keeps accepting this bad information of how to calibrate and so no one has designed a mount for stepper calibration which is insane. I designed a simple mount that should work with most indicators. I designed it so that I could remove my mirror bed and use the binder clips to hold it in place. Then you simply ride the point on something that will move while testing. Be sure to put at least a little travel on the shaft before testing so that you get an accurate measurement. Move the axes 20mm and use the same formula that everyone uses to calibrate the wrong way with cubes. (expected distance/measured distance) x (current steps/mm)=new steps/mm. Repeat this until you get 20mm on repeated checks. It may take 2 or 3 calculations to get it dead on. This mount is pretty generic and should work with nearly any printer. I used a clamp on the vertical extrusion to check my Z axes. I almost modified my design to allow for Z axes calibration mounting but you would have to read it upside down and that's a bit goofy. How accurate is this calibration? Well if an indicator is accurate within .01mm and my Ender 3 Pro bed size is roughly 220mm, then 220mm/20mm=11. 11 is the number of times the margin of error repeats across the bed. 11 x .01mm=0.11mm. So basically if I printed something that filled the whole bed then the farthest that the accuracy should be off is by only .11mm. In the USA here we call that .004" and I would say that's pretty darn good. Print the mount laying on its back and then you only need supports for the bolt hole.