An upgrade

The last post showed the broken foot pedal on our bio garbage can. I managed to epoxy it back on, but because it was so cold where I did it, the epoxy didn't fully set (and ran over the support so I had to cut through it), and within a month of further stepping, it broke off again. No saving it this time.

My printer has mostly been standing still, partly due to my own carelessness, partly due to parts failure. I neglected to level properly before a big print and ended up with so much backpush that the filament stripped, then the rest of the filament in the hotend oozed out. This resulted in stuckness that couldn't be resolved with a cold pull, because there just wasn't enough heating up going on. In the end I took the cooling part of the hotend off and placed it on a toaster (flatbed style, known as "Deathtrap" to non-Danes) until the filament became soft enough to pull. This bought me a bit more printing time before the aforementioned cracks reappeared, and I'm not going to try to re-glue that piece. Fortunately, I had printed another extruder block, which I'm now cleaning of excessive elephant's foot before mounting. I also tried, for extra reinforcement, to apply some contact cement to the side of the block. I imagine it can seep in through tiny cracks and bind it together a bit. Would be interesting to compare epoxy and various glues not for bonding two parts, but for reinforcing one.

In the meanwhile, I have turned 50 (who'd have thunk?), and in that connection my wife arranged a Christmas and birthday gift conspiracy to get me a new printer. Enough money came in to get me a Prusa i3 mk3s, and maybe also the MMU. It should just barely fit in my workbench. While the Mendel90 has been good, it has also suffered from some build problems and limited upgradability. The rest of the world has moved on, and getting proper bed levelling, motor feedback, a large print volume, a better plate, and many more improvements will allow me to focus more on the design part than on maintaining the printer. I will probably still keep the old one around (somewhere) for when I need more printing done quickly, but my day-to-day printing should be easier with the Prusa.

Printer back online

After a long hiatus, my trusty printer is now back online. The hiatus has partly been due to a series of problems, partly due to me finally getting my shit together to do a proper workbench in my room (another post coming on that soon). Among other things, I replaced my Melzi with a new and slightly nicer one, though I'm not now sure that the old one was actually broken - turned out despite my testing the D-sub connection was done wrong. I was tempted to get one of the TronXY models which come with nicer connectors, as connecting raw wires in a cramped space is not easy and rather error-prone. I just don't know if they're truly compatible, and haven't been able to find any evidence one way or another. They seem to be Chinese knock-offs, and what I have seen about them doesn't sound encouraging, but then people only post when complaining, so I don't know.

After a number of rewirings - it seemed every time I fixed one wire another started having trouble - I now have it printing again, except the print fan is dead. That's not just a wire problem, I applied 12V straight to it, and it didn't react. So that needs to be replaced. It shows quite clearly on this McBenchy:

Ridges on the brow and drooping above the door - sign of a missing print fan

I have changed the hotend fan to take 12V from the hotend + on the breakout PCB. This is in preparation for putting in the probe, which should use the spare P pin as signal. However, I would need to put in either resistors or a voltage regulator to get the signal down to 5V, so I will probably need to redo the board to support that. Yes, I could make a tiny side board for this, but I have had it with messy setups. At the same time, I could change the connectors to some that are easier to plug in and out. This is the most informative thread on the current layout wrt probes. That thread says to not put too much current through the shared thermistor ground, this fan uses 150mA, which might be a problem for the thermistor, maybe. The probe wouldn't add much. If necessary, I could draw an X limit ground wire, but I would rather not. I think the lack of spare wires into the breakout board was somewhat of a false economy, it makes it hard to upgrade. There are also potentially good links on this thread.