Build Your Own SLA/SLS

Hello there guys, I'm sorry to barge in like this, it's been a while since I last posted anything.

Anyway, I had a broken DLP projector (the color wheel started scraping) and I thought to make a printer out of it, so I ordered a printer from the kitprinter3d guys.

So I open the projector, an Optoma EP739H, eliminate the glass from the colour wheel, fix it to the printer (a standard bottom up, fexible vat job) and off I go.

Unfortunately, when I try to print something the background radiation is so strong that it polymerises a solid layer right off the bat, so the only "prints" I get are thin rectangular plastic wafers.

Can you tell me if you encountered a similar problem and how to fix it? I've been thinking about adding a filter, but I'm not sure what to get.

As always, thanks for the help!

How long between turning your monitor on and starting the print? You might need to look at installing a shutter to block the projector when not actively projecting a layer. It's fairly easy with a small servo. Ramps has spots specifically for this and the Marlin frimware makes them quite easy to use with the M280 command.

I use creation workshop as a host, so i have to manually block the beam until the last moment.

The shutter would help a lot indeed, but i still fear that the light coming out of the projector when "dark" would still polymerise the resin where it should not.

Could it be that the removal of the colour wheel caused this excessive lightning? Is there a way to augment the contrast?