Zero-Y backplate w cooling for Sprite extruder

thingiverse

Development and testing is done, but this description is incomplete, that's why this is marked as work-in-progress. This is a zero-Y backplate for sprite extruders with a volcano length hotend. It works great with the K1 hotend. It tries to keep the x-offset as small as possible by using the diagonal space. Partcooling fans and probe need to be on the left, so the right side stays accessible with the screws that fix the whole extruder assembly. The one thing it does differently to the other backplates I've seen is that it uses the backside of the heatsink for cooling as well. To achieve this, there's one M3 screw, that holds the bottom part of the PCB against the backplate, that I deemed unneccessary and that has to be replaced by a shorter one. You could also use the file "unneccessary spacer" to mount the stock screw, but it will obstruct airflow somewhat. It also features a guide to put PTFE tubing in, for reverse bowden setups. I find that it helps a lot with consistency in larger prints, especially vasemode. I run my 5015 fan at 12V with an inline 12V zener diode and a 200 Ohm resistor to reduce noise since cooling is more than sufficient that way. It needs to be a zener diode with a bigger power rating than usual, mine has 1.3W. There's a 12V drop across the Zener, so I use it to power 3 LEDs from a garbage find 12v ledstrip as a nozzle light. Free nozzle light from free energy! ;-) I'll add a little sketch of the wiring to make it more understandable. The one important thing to keep in mind is, the fan should draw more current than the LED, otherwise the circuit doesn't work as intended and the fan will see more than 12 Volts. (That's a problem on 4020 Noctua fans) If you don't feel sure about electronics, find someone who does, or don't do this mod, either way, I'm not responsible if your house burns down. I did two versions, one for 4020 axial fans, and another one for 5015 radial ones. Both have been tested and work fine. If you use a cr-touch, one corner of the mounting surface needs to be filed a tiny bit, bl-touch sensors fit right away. My bl-touch on the other hand is a tiny bit longer than my cr touch, which works well with the nozzle that came with the K1 hotend. If it's too long in your case and risks touching your prints, I'd try shortening it with a file, replacement pins are cheap, if you should ever need them. The holes are meant to be self-tapping. Instead of finetuning the print, I'll rather recommend printing them undersized and opening them with drills, if needed. Especially the 2mm holes for the two M2.5 screws are difficult to adjust for and very easy to drill to size. Print in PETG, PCTG, ABS ASA or other heat resistant filaments @ 0.2mm layer height. Tree supports, on buildplate only. You can block supports for the small part, where the 24pin ribbon connector is soldered, bridging works fine for that little distance. The fan placement and ducting was inspired by this [backplate by Lasse Lauesen](https://www.printables.com/model/438768-sprite-extruder-0-y-offset-and-5015-hotend-fan) So I'll cite him as a source, but it is based on my own ideas, drawings and measurements. Partcooling shroud is [this one](https://www.thingiverse.com/thing:6227632)