UM3 All Metal Hot End for UM2+

youmagine

If you don't have an extra UM3 print core setting around, I suggest using a 3D Solex HardCore PVA Print Core BB (Support Core). It gives the ability to change nozzles. They have another version with several sizes/types of nozzles, but it is more expensive and I prefer to choose my own nozzles. The BB comes with two 0.4 mm coated brass nozzles, which are limited to 260 C, just like the UM2+. The Solex nozzles have a finer thread pitch than the common M6x1. This is the same thread as the UM3 nozzles. Wrong voltage! The UM2 requires 2 12V fans connected in series (24 V). The correct blower is Delta p/n BFB0312HA-A116, which comes with two blowers and the new fan shroud takes 2 blowers and the stock print core cooling fan. Again, sorry for jumping the gun. I left some of the original pictures because my printers are in use and I can't shut them down right now. You also need eight #2 x 3/8 (or M2 x 10mm) self-tapping screws. Remove the heatsink/heater block/nozzle assembly from a UM3 print core. Don't try to disassemble the heater block from the print head, as the thermal break is very easy to bend and there isn't good space within the plastic structure to hold things well. Remove the screw from the top, cut the plastic webs just below the cooling fins, and throw away the plastic. Hold the heat sink with a pair of pliers and remove the long tube at the top. Throw away the plastic. Loosen the screw on the bottom of the heater block that holds the cartridge heater and thermocouple. Remove and discard the CH, TC, and circuit board. Disassemble the print head (aluminum stuff on the bottom) on the UM2. Save the print head cooling fan and the lower aluminum plate with threaded holes. Counterbore the aluminum plate as shown in the drawing to allow the tall SS piece to fit below the bearing in the upper part of the print head and for the nut part to have plenty of thread engagement on the heatsink. The 3D Solex print head has a little longer thread on the end of the heat sink. Counterbore the plate a little shallower. I've changed the drawing to show both depths. You'll need to cut two of the long screws as they will hit the print core cooling fan and the other will hit the plastic by the part cooling blower. One should be 1.82 inches (46.2 mm) and the other 2.05 inches (52 mm). Cutting the other two to 46.2 mm will make the assembly look better. Put everything back together. Insert the heatsink into the mounting plate, thread on the long entry tube, align the heater block so that the holes for the cartridge heater and thermocouple are facing to the back, mount the fan and blowers to the fan duct (two screws each), cut the plugs from the original part cooling fans and solder them to the blowers, and mount the fan duct to the mounting plate (two screws). Insert the cartridge heater and thermocouple into the heater block and tighten the clamp. Feed wires and mount the whole mess back to the print head plastic bearing housing. Plug in the blowers and fan. Convince Ultimaker to remove or raise the temperature restriction in the firmware, as there is no PTFE bushing to be damaged (or wear out). Convince 3D Solex to package their print core without all the parts you don't need, and maybe a mounting plate bored correctly. A kit with blowers, fan, and screws would make this a five-ten minute change-out. Happy Printing!