Glad you were able to find a solution simpler than rebuilding the hot end! - rdoby rdomunky - Mendel90
Hi all, Finally getting around to posting a summary of my fix for a problem I had with my M90, in which the thermistor sporadically gave wildly varying readings. This is what my hotend temp looked like after heating it up and then turning it off to let it cool: Nophead suspected a short at the thermistor. When I disassembled the hotend, I found that black ABS had seeped between the red thermaby rdomunky - Mendel90
Jens I experienced exactly the same problem with my Mendel90. As I understand it, the problem was that the thermistor cement had crumbled and/or been permeated by wayward plastic, causing the sensor to short out. I fixed it a couple weeks ago and was just about to post a summary of the fix. Stay tuned. Thanks - rdoby rdomunky - Mendel90
Great summary Neil. Bookmarked. Just curious, what PLA do you use with these settings? Thanks - rdoby rdomunky - Mendel90
Thanks Neil, that looks promising. I'll order some and post my results. BTW I did try baking the moisture out of the Blue Steel stuff, but it didn't seem to help. Now that I've poked around a bit with it I'm almost sure it's conductive when cured. - rdoby rdomunky - Mendel90
Hi all, Following up from a previous thread in which I was having trouble with my hotend thermistor. I am pretty sure that some plastic got into the cement that was holding the thermistor in place, and caused or contributed to a partial short and bad readings. I have a couple replacement thermistors (EPCOS B57560G104F THERMISTOR, 100K, 1%, NTC, RAD) but have not yet found a working high temp cby rdomunky - Mendel90
Actually, it looks like I probably need to take the red tape off and clean off the thermistor element. This is the temperature graph I just got when heating up the hotend (removed from the x-axis assembly, nothing touching the thermistor through the insulation hole) - rdoby rdomunky - Mendel90
Thanks Neil & Chris I took the hotend out and discovered that the thermistor had been rubbing up against the mount, making a small hole in the insulating tape: In this disassembled state, the thermistor reads a correct room temperature value. What material is the red insulation tape, and/or any other suggestions for fixing the hole? Thanks - rdoby rdomunky - Mendel90
Hi all, Pretty sure this is just a matter of a thermistor having gone bad, but the way in which it happened is puzzling. See the temperature graph here: The print was going fine until the temperature drop (195 to 190 after first layer) at which point the thermistor gave wildly varying readings for a period, then got "stuck" at around 190C even with the power turned off. I verified this byby rdomunky - Mendel90
Thanks Neil and dawa I think I've got everything set up pretty close to level (X axis assembly w/ respect to the frame, and the bed with respect to the X and Y axes). Agreed that the documentation is extremely comprehensive but every sentence counts! NOT a complaint by the way -- I'm reminding my students and coworkers to RTFM all the time :-) - rdoby rdomunky - Mendel90
Hi all New Mendel90 user here. So far I'm extremely impressed with the quality of the kit and its documentation. I was able to assemble everything and integrate a North American ATX power supply and got very nice print quality from the included pre-sliced Android robot. One thing that I'm wondering about is the process for leveling not the bed itself, but the X axis assembly. I understand thatby rdomunky - Mendel90