My N4Max build plate setup process for reliable printing
I bought a N4Max a couple months ago and upgraded it with X & Y linear rails. I did not want to adjust the POM wheels but the following procedures are applicable without upgrading.
I replaced all screw springs and center standoff's with urethane spacers. I mod'd a dial indicator mount model to fit the X linear carriage and my dial indicator (I put my model on Printables.com). I believe you can find a dial ind mount for a standard POM configuration. I compressed the two center mount spacers to ~50%, tightening the same number of turns for each. I then used the dial indicator to get the center area zeroed and worked my way out to tram in the rest of the plate. Takes maybe 10 minutes to get within a couple thousands of an inch everywhere the dial ind can reach. The bed was heated to 60C during the process. IF YOU DO THIS, YOU'RE GOLDEN until the bed slinging shakes the screws loose; it's been running a LOT and I haven't had to go back to the bed plate screws tramming yet.** After this you just have to do the next steps as described.
Before printing I soak the bed at the print temp for 20-30 minutes (longer is better); it is interesting to run screws_tilt_calculate a few times while soaking, it gives a good indication how much the plate changes from heating, it gets all taco'd then levels out. If screws_tilt_calculate requires adjusting after heat soaking, check Z-offset, set if necessary then run auto leveling to probe and create a mesh. I find I only need to run screws_tilt_calculate & reset Z-height when changing bed/nozzle printing temperatures drastically, ie. it's been printing PETG at 260C/80C for however many days or weeks, then I switch to TPU at 225C/35C or vice-versa.
I could NEVER get good 1st layer/adhesion with a little N4Pro until I started doing this, after success with this I was not intimidated with buying my used Max and I am consistently getting good prints.
** This has worked so well that if I ever need to re-tram the plate, I'm going to Loctite the two center screws and will likely never have to re-tram, just screws_tilt_calculate.
