Since people were curious what I would think down the road, and others were following with interest because their were thinking I getting one too, I'll add some more updates.
First, I want to retract one of the statements I made earlier, at least partially. The stock Prusa power supply isn't underpowered -- most of the time. Especially with the latest firmware (more on that later). During printing, both the bed and hot end are operating in PWM mode, which means the load on the power supply should be considered the time average, not the instantaneous load. A well designed power supply should be able to put out it full rated load for some period of time (usually in the specs). A well designed power supply should protect itself from damage, but otherwise be able to exceed its rated output for some (shorter) period of time. The Prusa supply does both just fine and the PWM control of the two heaters means that the average load over time is well within the power supply limits. I'd estimate that the worst case load when printing PLA is under 50%. Now, there is one point at which the supply is mildly overloaded for a significant period of time: initial warm up, especially for something that requires high bed temperatures, like ABS or polycarbonate. When the hot end and bed are both initially heating, the are one 100% so you are pulling at or slightly above the rated power supply capabilities. You can reduce the stress by heating them sequentially instead of in parallel. Is running the supply at 110% for a few minutes and print start a problem? Only time will tell there.
Prusa addressed on of the power supply issues with the latest firmware. The annoying click, in phase with the bed PWM has been fixed. The bed PWM frequency was raised to 62.5 Hz and given 128 levels. The PID algo is now a bit more gentle in ramping up PWM so the power supply doesn't go from nearly idle to 8A in microseconds.
As a last note on power supply stuff, it appears that some of the early Mk3 supplies did have an under spec part in them. The PTC themistor used for inrush limiting was to small and could go into thermal run away, resulting in spectacular failure. The power supply was updated to use a larger thermistor. My supply has the larger thermistor. I haven't put my stock supply back in service though. Mainly because I don't have a whole lot of reason to. The Meanwell is working just fine and I printed a new top panel and fan mount to an Arctic F8 Silent.
That change adresses the one problem I had with the Meanwell. The stock cooling fan was a small, noisy thing.
Now, on to further adventures in 3d printing.
My printer recently got a new home.
That's a Lack enclosure, based on the plans Prusa has on their site. The LED strips are drivin from a seperate 12V supply with a brightness control (you see it on the back left). The enclosure does very little for noise, but it helps stabilize the temperature for long running prints. It also, as important, helps keep dust and pet hair off the printer. It isn't in the above picture, but I have since dug out on of my Raspberry PI 3b's and camera. The camera is mounted in the front, top right. The Pi is just sitting on top of the enclosure for the time being. The Pi is running Octoprint. The Pi camera doesn't do the best for print pictures, but it's sufficient for monitoring the printer.
This weekend, I installed a 0.25mm nozzle to do some printing of highly detailed models. That eventually led to taking apart the extruder for the second time since I owned the printer. I was having issues with the extruder skipping for time to time, it was mainly just on the initial purge line. I got a print started and it looked to be running well before I for work. I got home to find the the printer had stopped extruding after about 3mm into the print and had been printing nothing for the next 10-15mm of Z height. The extruder was completely jammed. After much picking at it, I was able to get the filament out, but I went ahead and tore it down to check everything. The PTFE tube is showing the signs of abuse, but wasn't bad enough that I couldn't put it back together. I did order some new PTFE though. Right now, I'm blaming the skipping and blockage on the filament. Its Prusa white PLA. I had a spool of white PLA from 3D Solutech that I switched to and things are behaving much much better now.
The nozzle switch required resetting the Z offset and so I took the opportunity to re-level the bed, as the smaller layer heights will be more sensitive of variations in the bed. One thing to note, which I learned to hard way, the Mk3 has a firmware limit on the first layer of 0.15mm. You can't print with a 0.1mm first layer. Annoyingly, Slic3r PE won't give any warning if you try a 0.1mm first layer. It happily sets up the extruder flow for 0.1mm and tells the printer to print at 0.1mm. The printer happily ignores the layer height and prints at 0.15mm. The result is pretty much zero adhesion and very little hint as to why. I started out printing 0.15mm think calibration squares to set the Z offset and was very puzzled why they looked great, but the follow on 0.1mm squares were crap. Even worse, when you print multiple layers with the first layer at 0.1mm, the first layer is printed at 0.15mm Z, probably with no adhesion. If you get it to stick well enough to continue to the second layer, the second layer prints at 0.2mm, which is effectively a 0.05mm layer thickness, since the first layer was 0.15mm thick. Since the extruder is still trying to shove enough filament through for a 0.1mm layer, bad things happen. That may also have contributed some to my problems with the Prusa filament, but it certainly wasn't all of them.
I've got the first half of a very detailed Tie Fighter model printing at 0.1mm height.
That half of the model is a 47 hour print. It's about going for about 24 hours in those pictures. I'm going to have to get the DSLR out to actually get good pictures of the detail, when it's done. Just looking at it while it prints, it's pretty impressive. The printer has done an admirable job with the detail. It has only had problems with one area, which turns out to be a problem with the model and slicing and looks pretty much impossible to print correctly on an FDM printer. It is actually an error, as the back half that matches up with it is even worse and actually has holes and floating pieces in part of the model. That's what led be to actually start looking at the model and how the slicer was interpreting it. So, I've pretty well progressed to the point where I have to pay close attention to what the slicer is doing to ensure I'm not asking something impossible of the printer.
I'll spend some time, on occasion, browsing Thingiverse to see what neat new things people have created. Doing so, and looking at people's makes, has made me realize just how high the overall quality of the Mk3 prints are. Yes, there are some known issues with vertical artifacts on the surface, especially on faster prints, but when I look at the makes many people post, I can't help but think "man that's a crappy print". Now, to be fair, there are some spectacular makes posted, but I can make a pretty edjucated guess as to the "level" of printer that someone has from looking at their pictures. It certainly re-inforces my decision to get the Mk3. Yes, there is a fair amount of tinkering to get it dialed it, but once you do, it will turn out nice print after nice print (if you can avoid the desire to tinker and upgrade).
--SS
