Monoprice Select Mini V1 upgrade for E3D-V6 HotEnd

thingiverse

The stock hot-end on the MPSM-iiiP V1 is a nice cheat, but it's very clunky and difficult to service. My iiiP-v1 printed well, but leaked molton PLA out of the heater block... so it's not great for the long haul and needs to be replaced by the E3D-V6 style hot-end & bearing holder similar to that used on the Select Mini V2. Background: The V2 and V3(pro) use some variant of the E3D-V6 hot-end. The hot-end bearing assembly used on the V2 & V3 do not appear to be available. As a result I downloaded and printed several alternative mounts currently on Thinigiverse to handle E3D-V6 hot-ends and found each to be lacking in some manner. In my opinion, the best overall redo on this is based on the design by justinschmitt. It makes the most sense to replace the original hot-end and bearing holder with a design that's zero offset so you don't lose build volume. It also seems silly to go with a replacement that has screw or nut hardware that's hidden by the drive belt. The basics of the justinschmitt design resulted in no significant change in nozzle location when homed. In fact, the offset following the completed installation was within a half turn (clockwise) of the four bed leveling screws !!! Preparation and Installation: Prior to any disassembly, buy a silver or gold Sharpe and mark the belt where it locks into the bearing "truck" on both the toothed and smooth sides. I did not want to figure out the proper belt & tension spring position after the fact. The sight window helped to make sure I centered it just like it was from the factory. **** The finished and printed models - installed using the original heater, thermistor, and fan with NO need to change ANY wiring if you're careful with your existing heater, probe, and fan. !!! **** READ-ON... **** Treat the thermistor with respect. **** It's a tiny glass ball with stiff wires coming out of it. Be very careful bending those wires to accommodate a screw between the two legs. I created a tiny Kapton-tape washer to go under the head of the screw for added wire insulation. I watched many videos on the upgrade of the Select Mini v1, and feared the day I would actually change out the original E3D holder. As it turns out, you do NOT have remove anything but the two end cap screws and the socket head screw that holds the end tension wheel. The X-Axis cover pivots out of the way just enough to use the x-end-puller and swap the parts. The puller design by **** Kadah **** is excellent. You do NOT have to remove the tension spring from the belt. The hex head screw in the end cap releases the belt and gives you the slack to unhook the old bearing holder and easily re-installs with the new one on the rails with the belt slid in place. You can add the zip ties and belt lock later when the whole unit is reassembled. Using the pullers, you should be able to remove the older assembly and install the new one in 20 to 40 minutes depending on your comfort with these kind of upgrades. Kadah also gets a high-five for his AMAZING & accurate rendering of the entire Select Mini. It was nice to be able to check my dimensions against his rendering. **** Kadah's pullers saved me the trouble of making my own pullers from scratch and more importantly reminded me that the x-End Cap is a bitch to remove and his tool kept me from going animal on my MPSMiiiPv1. **** Before using the pullers: MAKE SURE to REMOVE the SOCKET HEAD SCREW THAT MOUNTS THE BELT END-ROLLER otherwise you could ruin the belt and have a new adventure. While using the remover (repeatedly tighten top, then bottom one turn each) I heard a loud SNAP and surely thought I'd broken something.... Turns out it was just the superglue on the rods ends letting go. After removal, I used a folded up tissue soaked in nail-polish remover (acetone) wrapped around the rod ends to soften the glue and remove it so as not to jam up the internals of the old bearings on removal and the new bearings on installation. I left these tissues on for a while to soak into the glue, then scratched off the remainder with my finger nail and wiped them clean. You do NOT have to use superglue for re-assembly... as long as the end block feels snug on the shafts. The bearings in the original V1 assembly can be reused and are easily pushed out by hand using the corner of a piece of wood to push against the outer barrel of the bearing. Once you move them 1/4" or so they will almost fall out on their own. Notes about the files: 1. there are five (5) versions of the bearing holder with different hole sizes. They are in series where each is 0.006" larger. Print a slice of each and check the bearing fit before printing the entire assembly 2. The design will work without the belt lock. Using the belt lock with a pair of zips ties means the assembly will never move its position on the belt. 3. the spacer clip-on for 3mm (0.121") Borosilicate Glass sheet with cropped corners (for level screw access) in conjunction with 0.5mm (0.018") silicone thermal transfer mat. Total offset is 3.5mm (0.1367"). The hole in the top is for a set screw to lock it to the plastic z/x mount. You have to remove the rear column cover to install this clip-on shim. 4. I uploaded STEP & STL files for just the mating block that clamps the top of the E3D-V6 so you can model your own fan holder it you have a better idea. I may upload improved fan holders in the future. I used heatsink paste that's sold for computer processor chips to install the heater cartridge and thermistor. This helps with heat transfer and makes sure the thermistor reads dead on. I also used this on the throat threads where it threads into the heatsink. The heatsink of the E3D-V6 runs stone cold while printing with my parts. The original stock heater cartridge from MPSMiiip V1 fit loosely in the cheap $12 (delivered) E3D-V6 hot-end I bought on eBay from a U.S. seller. So, I wrapped it 358 degrees (to avoid a thick overlap) of it with aluminum foil from the kitchen to close the gap. I painted a little heatsink paste on the heater cartridge to transfer heat better, and also to act as an adhesive to keep the foil in place during assembly. This may seem like a bush-fix, but remember the hot-end block is also aluminum, so using foil as a shim is safe. I painted the hole inside the heater block where the heater cartridge slides into with the same heatsink paste. This makes sure it conducts heat well on both sides of the foil shim. The $12 eBay assembly included a fan, a blue fan clip-on, the heatsink, heater-block, throat, nozzle, two tubing connectors, a thermistor, a heater cartridge, and more than two feet of Teflon filament tubing. WOW, what a deal ! It was less problematic to use the existing heater and thermistor that shipped with the MPSMiiip. I was concerned about the behavior of the thermistor - and bought a spare from Gigdigit just in case the original crumbled in handling. Gigdigit appears to have their finger on the pulse of Monoprice printers and is a recommended parts source by the support agents at Monoprice. I feel that using the original thermistor or a proper replacement is key. Perhaps one day I'll try the thermistor and heater that came with the cheap E3D and report back. Glass Bed Experience: Following the installation of the E3D-V6 and a glass bed I realized that the aluminum bed on my V1 was bent and acting poorly. I removed the glass plate and its silicone pad and used a straight edge steel-ruler diagonal from corner to corner showed the bend was more than 1/16" of an inch. I removed the bed while still wired and flexed it a bit to remove the bend. I was successful and the glass plate now sits flat enough that the printing is reliable. The flatness error is small enough that I could shim it with spare scraps of the silicone mat if needed. The real fix for this is buying a custom cut 3/16 aluminum bed and use longer corner screws along with heat sink paste to slap it on top of the existing heated bed and get good heat transfer. ((just leave the original bed in place and add a thicker flat bed on top... you'll loose a few millimeters of build height and the bed will take a bit long to come up to temperature, but the issue will be solved. if you add to the bed you'll also have to shim the z-limit switch to match its thickness.)) Also worth noting it that the thermal heat sink mat is sticky enough (like saran wrap) that I print without the need for any type of clip or bracket to hold the glass. If you're new to 3D Printing, glass beds are used in conjunction with a purple Elmers Glue Stick and is one of the best and most popular methods as a replacement for painters tape, and the like. It's nice to now have a 3D Printer with a hotend that's now sooooo easy to service. The Select Mini is a secondary machine for me and is very compact and quiet.