On 6/4/20 4:50 PM, Chris Albertson wrote: > One more question. How do you post-process the printed parts? Do you use > a separate UV lamp or sunlight. Same with cleaning? Just use a bucket of > alcohol? I know they make SLA post-processing equipment, ultrasonic > cleaners, and UV booths.
I'm still experimenting with post processing. I'm fairly new at resin printing so probably not the best source of information. I want to be able to run limited production so I want to simplify the process as much as possible and automate it as much as I can. For cleaning the printed parts, I'm having the best results with isopropyl alcohol. I spray it on and scrub gently with my gloved hand and then spray the part again and let the IPA rinse drip off and allow the part to air dry. I had seen some encouraging videos and posts online from people getting good results with a detergent such as Simple Green in an ultrasonic cleaner so I bought a larger ultrasonic cleaner. The first parts out of the cleaner looked very good but every part after that was progressively worse. The part surfaces were increasingly cloudy and there was some gritty orange precipitate in the bottom of the ultrasonic tank that would settle on the parts. I don't want to drain the ultrasonic tank each time or I'd be better served by spraying IPA on the parts. Some resins apparently don't like aqueous cleaning. At the very least, the cleaned parts should be allowed to dry overnight before the UV post cure. I thought I'd be clever and UV post cure the parts in the final rinse tank. I was planning to ultrasonically wash the parts, rinse the parts in a tank of deionized water, then do a final rinse in another tank of DI water that's agitated with a submersed pump. After a minute of agitated rinsing, an Arduino would turn on the UV light in the lid of the rinse tank to UV cure the part underwater. I did some research and others were UV curing under water. I tried it and the results were OK but not great. Then I read where some resin manufacturer stated that the UV post cure should not be done under water and the parts should be thoroughly dry before they are post cured. I'm still experimenting. I bought several different resins to test but have only tried two resins. I need to do a lot more experimenting but I've been busy designing and printing parts on the FDM printers lately. The cost of the MSLA 3D printers is low, and the print resolution and part strength is high, so resin printers are going to be gaining popularity and these post processing issues will become much less hassle and mystery. I've looked at some post processing equipment and read reviews and so far I'm underwhelmed. Someone needs to make a Resin Printing Best Practices video or PDF. If it exists, I haven't seen it. There are some useful tips but much of the information is contradictory. I need to make a fixture to gently scrape the parts off the build plate in a controlled manner. That can be a treacherous process, fraught with peril. Maybe I'll devise something that washes the parts on the build plate by spraying everything with IPA to clean the build plate at the same time, then scrape the clean parts off the clean build plate to avoid gumming up the scraper mechanism. That would be better than slimy gooey parts flying across the room, or gouging a resin covered scraper 10mm into my hand. I bought an inexpensive but very nice 30W UV lamp, Amazon ASIN B07XCQ5C58. It does a good job of post curing the parts. I've seen where people build curing boxes with UV LEDs and line the box with mirrors, not realizing that glass blocks most of the UV. They'd have better results with polished stainless steel as a front surface mirror. _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
