Topic: How to increase UV light output from 4K DLP projector
Hello fellow stereolitographers, I have a problem with home-built DLP 3D printer, and I would appreciate any feedback. I've built DLP 3D printer with following specs:
-Benq TK800M 4K DLP projector (colorwheel removed).
-2x Genuine linear 15mm rails
-Genuine 1605 ballscrew
-Nema 23 closed loop stepper
-nanoDLP + RPI 4
-Aluminum FEP vat.
Print area of this printer is 500x281mm (cca 20s exposure for 100um), but when I tried projecting on this large area, I got really bad results. It seemed like the projector was lacking UV power. So logically, next step was moving projector closer to the vat to get more UV power.
So, after moving projector closer, projecting 250x150mm image (cca 6s exposure for 100um layer), it improved the results drastically. I could get solid print quality, but I know this is not the maximum quality I can get with this type of printer. It seems like I am still lacking on UV power..
I always get some kind of 'Z lines' on my print. I have vacuum holes in 3D model.
I've tried different lift speeds (from 30 up to 2mm/min), and slower speeds do seem to improve the results, but Z lines are still present.
I think the problem is that normal spectrum of projector heats up exposed layer too much, and it does not solidify enough to hold It's shape during peeling event.
I just for the life of me can not get solid print results.
I just need to increase UV output from projector.
I've tried following:
-removing color wheel (decreased curing times by about 40%, but still not enough UV).
-tried replacing lamp UV filter with regular borosilicate glass (after about 10 mins running, I've cracked 1 lens inside DLP assembly, so after about 2 months of searching for replacement, and successfully replacing the cracked lens, I'm at the beginning again..)
-I've experimented with creating focused UV light beam from 50 and 100W LED module. (Tried creating 3 lens assembly in order to focus the light, tried installing it in the projector, and displaying image: result: the lenses inside projector filter a lot UV themselves, so the image was kind of dim... Than I tried using normal 10W 460nm LED (royal blue) with the same lenses, and the image was much more brighter (indicating the loss of UV light inside projector light pathway.)
So FINALLY, my question is: - how can I increase UV light output from projector? I'm kind of out of ideas..
I've found some industrial 4K UV DLP projectors, but they retail at about 6.000-10.000€.
Pictures can be found in the following 4 links:
Sincerely,
Jonathan
