This build wasn’t a straight up kit so I ran into issues. Here are some of those issues that occurred after building my Prusa MK3x. From Prusa I had gotten all the steppers, the sensors, and various other parts. The frame pieces I got from Aliexpress. The controler board I got from Ultimaker, but it is the one that Prusa also uses. So this is sort of a Frankenstein build. This build has been in the making for quite a few years. I should have just gotten a complete kit from Prusa and built that.
Over the years Prusa has upgraded its MK3 printer line with the latest iteration being the MK3S+. After I finished the build I plugged it in and tried out the calibrations. While the stepper motors were functioning correctly, things weren’t working. The filament sensor didn’t seem to work. The wiring was correct, but it didn’t know if the filament was loaded or not. The printer kept going through its bed leveling routine before doing a print. So I had to turn off the filament sensor to continue. Another issue was that the extruder was not working. The stepper motor was turning, but no filament was extruding. The firmware does make you heat up the bed and the hotend before you attempt to do so. It seemed that filament didn’t go all the way to the hot end for some reason. So I took apart the hot end and I saw that the PTFE tube in the heatsink was deformed at the opening. I had another piece so I replaced it.
I reinstalled all the pieces and tried again. While I was able to insert the filament a little bit more, I still couldn’t extrude any filament. So I took apart the hotend again. I looked into the hotend and there was a little bit of plastic blocking the inside of the tube. The plastic bit had broken off of the retainer clip for the PTFE tube that fit into the heat sink. Not sure how that happened, but I replaced it.
After I reassembled the extruder, I tried again to extrude some filament and I was successful!
But I needed to check the tension on the gears in the extruder. There might be too much tension. I checked the tension on the belts and adjusted them to be with in the stated tolerances. I used the online app that Prusa had on their website to test the harmonics of the belts after you pluck them. It seems to work after a fashion.
I did a few test prints and I see that I still need to do some more adjustments to my prints up to par. One thing is that the bed surface probably should have been cleaned, but I just wanted to see if I could even print. Remember I said that the filament sensor didn’t see to work, I had to turn off the filament sensor in the settings to even get a print to start. Part of the printing process the printer does a bed leveling check and goes over like 9 different points on the heatbed taking measurements. Well after it did the check, it wanted me to unload the filament and then load it back in again. It went to do the test again. And after it finished the second time, it again wanted the filament to be unloaded/loaded. I did that again for a third time before I thought I would turn off the filament sensor in the settings. After that I was able to start printing. They weren’t very good prints but it was trying. But it is a work in progress! Need to make more adjustments.
My z offset set apparently is still too high. So I need to lower it. After trying a few different Z offsets, I was able to set the Z offset to -0.850mm and get a good first layer. After that I was able to get a nice print of the Batman logo.
The feeding of the filament just didn’t seem correct also. I believed that this was throwing things off. Since the extruder setup I have on the printer is a MK3/MK2.5 type, there were two allen screws that needed to be adjusted. Looking at the prusa site, it said that the top of the allen screw heads should be flush with the hole the went in. Previously I had each around 8 full turns in. I made it flush like the Prusa guide noted. Then I started over with the first layer test.
I decided to use an IR filament sensor instead of older type I initially installed. So one last thing I did was to print out a Bondtech IR filament sensor housing adapter that I found online. Due to the parts I have, the older non IR filament sensor fits my extruder housing, but not the newer IR filament sensor. While the print turned out great, I had to order a newer IR filament sensor since the rev I had was 1.1 and only rev 1.4 or above works with the firmware.
Until next time. Happy Printing!