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Glass bed and heater rewire mods to Monoprice Select Mini v2 3D printer
by snm, December 7th, 2019
I wrote about the Monoprice Select Mini v2 3D printer after extensively using it early last year:
- 3D Printing with 3D MARS white PLA: pass-through wallplate, paper towel holder, right-angle spool holder, shower curtain rings, and a prototype case
- 3D printing with the Monoprice Select Mini v2: first impressions and prints: a saddle, knob, guard, guide, spinner; a cube and clip; squeezer, holder, dish; case, stand, fingers, and carousel
but since then, prints have started failing, causing the printer to fall into disuse.
What went wrong? The common cause of the print failures can be traced to the bed. The MPSM comes with a BuildTak surface, but it doesn’t last forever. Even after carefully re-leveling the bed, there was only a small area of the surface I could reliably successfully print on, a frustrating and limiting experience.
To revive this printer, it is some to perform some much-needed upgrades.
Glass bed
The first upgrade I’ll perform is replacing the aging BuildTak surface with a fresh new and glass bed. This is quite a common upgrade for the MPSM, because glass is much flatter than BuildTak, making it easier to consistently level and successfully print on.
Ordered this borosilicate glass bed from Amazon:
It is cut specifically to fit the MPSM bed, conveniently. Using a suitably sized picture frame or mirror or having a piece of glass cut to the required dimensions is another option, but I went with this precut piece.
For bed adhesion, ordered these gluesticks:
Lastly I bought this these thermal pads, though I didn’t end up using them:
Now that ordering the parts is out of the way, time to prepare the bed. You’ll need a Z spacer to adjust the Z limit upwards so the extruder nozzle doesn’t hit the glass. I printed this one, the last print on the dreaded BuildTak:
This Z spacer took 3.02 meters of filament, 8 grams, and completed in 1 hour 10 minutes, for an estimated cost of 15¢.
Now to install the glass bed. First remove the BuildTak with dental floss:
Some other guides recommended removing the adhesive with acetone and attaching the glass to the bed with binder clips. I didn’t have either, but fortunately, the Buildtak came all off in one piece, leaving the adhesive mostly remaining on the heater block:
So I stuck the glass bed directly on top of it, with the previous adhesive, and it stuck just fine!
No tedious removal or buying extra clips needed. Easier than expected.
Your mileage may vary, but with the bed stuck on top of the original adhesive, and after applying a thin layer of purple gluestick on top of the glass, I was able to print without any problems (and without any build plate adhesion techniques (brims, skirts, or rafts)):
Bed rewire
A necessary upgrade for reliablity according to /r/MPSelectMiniOwners, this upgrade involves rerouting the bed heater and thermistor wires so they don’t rub against the housing as the bed slides along the axes. My favorite guide describing this procedure:
Printed the models linked in the YouTube video, http://bitchen.com/kb9rlw/bed_heater_cable_mod.zip:
| Model | Est filament (m) | Est filament (g) | Actual time (hh:mm) | Estimated cost |
|---|---|---|---|---|
| cable_brace_2.stl | 0.93m | 2 | 31min | 3¢ |
| MPSM_Passive_Cooling_Panel_NO_DRILL_REMIX_-_Part_2.stl | 4.65 | 13 | 2h 32min | 21¢ |
| MPSM_Passive_Cooling_Panel_Split_-_Part_1.stl | 4.58 | 13 | 2h 56min | 21¢ |
Here’s the stock sheet metal panel compared the to printed two-part panel:
Opening up the case to reveal the control board:
Unplug the heater and thermistor cables:
Unrouting the cables from the heated bed, sure eonough, they were nicked:
Should have performed this upgrade earlier, but better late than never. Could have been worse. 🔥
For the cable cover, there were cable chains you could print, or cable sleeves to buy, but I used an old enamaled wire I had lying around, which was wound around a pencil. This fit all the cables perfectly, and snugly attached through the cable brace:
After completing the rewiring, here is the final result:
Much better! The cable now has room to safely flex without damage.
With these two upgrades, the printer is now ready for some serious business.