Backlash Compensation: Test and gcode Compensation Program

thingiverse

tldr; Backlash Test i made and a program to get rid of it when slicer, firmware and printer won't do the job. <b>USE AT YOUR OWN RISK</b> <b>Uneven circles, crappy Infill and gaps between walls.</b> Thats what i dealt with. After some time i realised: My printer suffers from Backlash (when the direction of an axis changes, the movement of the stepper isn't transfered to the nozzle directly and it loses some movement). This caused that, when the angle of return on a 100% infill was "proper", the nozzle would extrude over the same line twice, then "skip" the next one. Circles didn't have uniform diameters and walls didn't bond in specific angles which caused airgaps. There are already some good backlash tests here (i first used: thing:2256550 ) But when tightening all belts, pulleys and steppers won't help anymore, there has to be another option. Cura and marlin don't have the answer afaik so i looked out for another option: altering the gcode itself. thing:979377 already tried this. But since it displays the gcode, it. takes. for. ever. (>1h to load a normal sized print) It also has a problem with long straight extrusions (e.g. 100% infill lines). They still suffer from backlash (gaps between lines) and only get shiftet a bit in their angle. Furthermore Start-/End-codes get messed up. If you want to try it, be warned that the nozzle doesn't run into your print when it is finished ;-) <b>Thats why i came up with my own code.</b> After a lot of testing it works for me like a charm and i built in some safety options so i can share it. But still: As they say, the devil never sleeps. So be careful and visualize the new .gcode files befor uploading to your printer. (I use www.gcode.ws) <b>How to use it and how it works:</b> Your start code needs to contain G90 to signal Absolute Positioning, otherwise nothing will be altered. Put the .exe in the same folder of your .gcode file. Copy the name. Start the .exe Enter the desired backlash compensation for x and y, paste the name of the .gcode and watch it convert (takes a few seconds). You will get a new file, so it won't alter the original one. Antibacklash analyses the gcode and whenever X or Y makes a positiv movement it adjusts the coordinates with the selected backlash-value. When the nozzle makes a turn (from positiv movement to negativ or reversed) it adds an additional empty travel move to add/remove the backlash befor performing the actual move. The nozzle won't move in reality, it just compensates the backlash. That way even long parallel lines (100% Infill) get handled. Only G0 or G1 movements get changed. The program will alert you if you have any G91 (Relative Positioning) moves in your code until it switches back to G90. These parts won't get touched. But since they are usual in the end-gcode for moving the nozzle away from the bed and retracting after the print finished, this won't affect us at all. After that you should be good to go. To check the gcode i simply use gcode.ws to visualize and notepad++ to compare the old with the new version of the files. Try it first with any backlash test to get the right values. My workflow is displayed in the pictures. The first two are without and with too much backlash compensation to see if it works. After that i trimmed the settings until i got to the right values. How to print my test and interpret the results is explained later on. I didn't have any problems with Antibacklash so far and don't expect it. If you come across any unexpected issues, feel free to share it. But keep in mind, Antibacklash is a free program and it comes without any warranty. <b>Use at your own risk!</b>