Vivtek DH913 Retrofit
My Draken has been working well, so I bought another one from 3D Facture so I can do some experimentation with different configurations, etc. I was one of the ultimate backers, so I have the first revision of the Draken design. It was nice to get one of the new ones that has all of the enhancements made so far.
The first modification I made was to use a Vivitek DH913 projector. This projector comes from the same line up that is used in the B9Creator printers. It is known to have good light uniformity and its optics are better than the ones that are in the Acer H6510BD. I found a used one on eBay for $750 with reported little lamp use. Brand new these projectors are $950-$1000.
The DH913 manual had the measurements for the mounting holes on the bottom of the projector housing. Using some CAD software, I created a paper template and used that to mark on the existing projector mounting plate two holes to help secure the projector to the plate. These two holes along with the three rubber bumpers helped stabilize the projector. I purchased two aluminum standoffs ($1.34 each at McMaster-Carr) to provide more rigidity as well as some M4 screws ($9.63 for a bag of 100 at McMaster-Carr) (the Acer requires M3 screws).
The projector is larger than the Acer, so fitment is a concern. Luckily based on where I positioned everything, it cleared the side wall.
I did not modify the lens at all in this projector, so when I mounted it into slot 3, I was not able to get the lens to focus onto the bottom of the vat. The only add-on solution I could come up with was the use of close up lens filters, typically used in photography to allow longer focal length lenses to act more like macro lenses for close up photography. While the actual lens diameter is smaller, the outer ring was very similar to a 77 mm diameter filter. I picked up a set of Tiffen close up lenses ($75.95 at Amazon) to try to reduce the focus area. The outer ring is not threaded, so I needed to use some painters tape to hold it on top of the ring so it wouldn't shift.
I needed all three close up lenses (+7 total) in order to get the image to focus at slot 5. The build size is similar to what you'd get in slot 1 and after calibration, I was able to get a 30 micron XY print.
The Vivitek pours out a lot of heat. So much that the metal shelf where the vat is installed was very hot to the touch. I added an exhaust fan to the right side to help get rid of some of the heat, but I think I need something larger. The 120 mm case fan I do have doesn't line up with the holes on the side of the chassis, so I will need to think of something else.
Here is an example print that is used by the Reify Solus guys to test their printer (props to them!) at pre-calibrated settings. It is 50 micron Z with a reported XY value of 28 micron. ;-) I apologize for the photos, I used my Sony point and shoot camera instead of my nice DSLR.