Custom CP40-Capable SMT Nozzles for Lumen PNP

prusaprinters

Hi all!I struggled with OpenPNP vision pipelines with the standard black-oxide coated CP40 nozzles. With the bore being low contrast, even runout calibration could sometimes prove difficult.The way I resolved this was by developing a replacement nozzle that was resin printable in any color! By using a bright color like green or blue, you can easily remove the nozzle and background using OpenPNP and Chroma Keying. These nozzles are compatible with the brass CP40 Nozzle Holders you see everywhere, and those specifically included with the LumenPNP. https://www.aliexpress.us/item/2251832292952501.htmlFor printing, I used a Elegoo Mars 4 Ultra, with Elegoo's Mint Green ABS-like resin. https://www.amazon.com/ELEGOO-UV-Curing-Standard-Photopolymer-Printing/dp/B08S74VFYL?ref_=ast_sto_dp&th=1I used the following print layout and settings with the standard 0.01mm layer height.After printing comes the hard part: Post processing. Wet resin will get stuck due to surface tension on the inside of the nozzle after printing. Soaking them in an ultrasonic cleaner of 90+% IPA for a few minutes will loosen some of it, but you really have to force IPA through the nozzle a few times to clean it all out. This is critical, because if you cure the nozzle with any wet resin still stuck inside, you will get a clogged nozzle.To force IPA through the inner bore, I use a small syringe without the needle. This is the exact syringe pack I used: https://www.amazon.com/gp/product/B0BV67Q46L. There are other syringes that might work better, this is just what I had on hand. The ones I would try next are the needleless irrigation syringes meant for dentistry.Remove the needle and use the syringe to pump/force IPA through the nozzle. I found the best way of doing this quickly is to wear a good pair of nitrile gloves, dunking your hand, the nozzle, and the syringe in a bath of IPA, placing the head of the syringe into the bottom of the nozzle, and using the syringe to push and suck IPA through the nozzle while it is all submerged. You only have to do this a few times for each nozzle. Once the wet resin is cleaned out, cure with a UV lamp for 2-5 minutes until hardened.As a bonus, I also include an FDM printable nozzle holder for the lumenpnp specifically designed for these nozzles. Nothing special here, but I really like the recessed nozzle base design which keeps the nozzle somewhat loose in the holder without it falling out.