MP Select Mini 3D Printer

Disassembled MP hot-end, $10 

In 2016, I got my first 3D printer for $230. Now that I've been through several spools of filament, I'm starting to understand how deep this hole goes. The journey that began with a test-print, then learning some software, designing stuff, has eventually led to tearing into the machine and replacing broken parts.

First the $2 fan stopped. To replace that I found it was a 12v 30mm fan, which is interesting because some expensive printers have 24v, big heaters, larger dual fans. My MP Select Mini is fine for PLA printed slowly (20mm/s), but not for speed or exotic plastics.

I've replaced the painters-tape print bed. The expensive machines have self-leveling, but on this machine I have to remember to do it. It's easy to forget and, not set correctly, the painters-tape got damaged. Painters-tape isn't great at holding prints either; I usually get lift around the edges. The expensive machines use something nicer like removable PEI-steel build plates.

The $2 heat-break clogged. The PTFE tube inside the hot-end bonded with melted PLA and to replace that part is a bit of a hassle; the hot-end disassembles into a dozen tiny parts and the heat-break is in the middle of all that. There shouldn't be melted PLA inside the heat-break. Here the expensive printers do a better job regulating heat, and also at being easy to service and clear.

And it was tricky to align and load filament through all these parts. I'd use sandpaper to round the end of the filament, otherwise it would catch on things. Something like the nicer E3D V6 Lite has a one-piece throat to solve this problem.

E3D V6 Lite in mount adapter, $60

Since the MP Select Mini has some non-standard parts, it's work to find perfect replacements. I find myself measuring parts with dial calipers before ordering. It's a precision machine, and if a nozzle is too big, then it could hit the bed. Monoprice doesn't have much in parts. The expensive machines have name-brand parts, in-stock.

The heat-bed stopped working when it's $1 thermistor quit. Things like nozzles, belts and heater-cartridges, do wear out and will need to be replaced. But in my case, it was these wires under the bed coming apart, so I re-routed new wire through a new 1/2" hole. I've never seen these beds in-stock, so the next fix might mean cutting a custom aluminum plate, with standard heater and standard thermistor.

MP Mini bed re-wire, $0

During the previous events, I discovered a stripped sheetmetal screw. This printer generally has ok hardware where you will see it, and cheap hardware where you won't. Since I don't have a welder, I'll glue-in a twenty-cent threaded insert from HK.

All of this is a long way to understand why something like the Prusa i3 MK3 is $750. I understand there are people that hot-rod their MP Select Mini - I salute them. My plan is only to see how long I can keep this thing printing.

Not everybody is ready for this level of tinkering. I'd recommend this inexpensive printer to folks that own wrenches and screwdrivers and aren't afraid to use them. Consider it part of the entertainment.