Build Your Own SLA/SLS

Two weeks ago I stumbled across an Instructable about building a dirt-cheap SLA printer using a DLP projector, DVD Laser gantry and Legos and Kenects.
After poking around here and a few other sites, which all pointed me back here, I decided I could jump into this at that price range.

So, I've ordered an Ask Proxima A1200EP projector, which seems to just be a re-branded IN2104. Should be arriving on Monday.
From what I've read here, at the very least I need to remove the UV filter from the bulb.
Not positive the color wheel needs to go?
And I need to shorten the focal distance to get my resin to cure? or is that only for resolution?

I have a scanner I'm hoping to use for the Z axis. This gives me a potential of nearly 300mm build height. With a resolution of 4800, I calculate that to be nearly 0.06mm steps, but I'm new to this.
The down sides I see is the scanner only has 1 linear bearing and a rail as well as a belt drive. I'll need to find a way to keep it from twisting around the rail when I stand it upright.

I've seen a few projects that used a flat build platform, but most seem to be perforated. I've even seen at least one project using copper-clad perf board. I'm planning to use that for my first platform. Hopefully I'll make progress on this and share some photos as I go.

Cheers,

John Gay

I'm not afraid of opening the projector, just more interested in how much I need to mod it.
1) Not sure the color wheel needs to go from what I've read. I know there's a UV filter glass on the bulb assembly, but from a few comments, the color wheel might be fine left in. Unless someone had particular experience that says otherwise.
2) Adjusting the focus closer. From what I've read, this is partly to get the X-Y resolution smaller, and partly to improve exposure times. Since I'm going for top-down, sitting another lens onto the existing lens conflicts with gravity (-= Adding a spacer seems easier without much hacking on this model from what I've read. It arrives today, so I'll get a chance to see tonight.
3) Another thing I haven't given much thought to: a shutter? Is it necessary? I do have a few solenoids lying around if I really need one. However, I've also got the RS-232 commands for this projector. Not sure if there's any help in there yet. Something else to poke around at.

And these are just a few of the projector questions I'm tossing around.

Just got my projector. Bought it on eBay for ~$50, now I know why. It's got quite a few dead pixels )-=
Now to see if I can work around those, or get another projector or replace the DMD chip in this one.

1) Removing UV filter and color wheel depends on lumen output (I've heard 2,000 lumen thrown out as a benchmark for unmodded projector use), projector design (removing the UV filter can cause cooling issues, but some projectors run fine), lamp type, resin type. I think you'll need to get some real world empirical evidence/data curing your specific resin with your projector to know since I'm guessing you bought a projector that's slightly off the beaten path for this application.

3) Found an old Sony video tape recorder at Goodwill. Lots of nice stuff in there including a shutter driven by a little 4-wire motor. Food for thought, I suppose.

Actually, it's an Ask Proxima A1200EP which is just a rebranded InFocus IN2104EP.
Got the UV filter off because I've heard the IN2104 won't cure Makerjuice with it on. Haven't touched the color wheel. Just hoping I don't need to.

I can get the projector to focus sharply down to approximately 6-7 inches wide without modifying anything else. Guess I need to get some Makerjuice now and start testing exposure times and resolutions?

Had a good look in the scanner I'm hoping to use.

The stepper is 12V 5 Ohm with 3.75 step angle with two reduction gears for the belt drive. There is one round shaft that attached to the molded plastic case of the scanner. The scanner claims a resolution of 4800 over the nearly 300mm length of the scan area. I calculate that to be about 0.06mm per step but that's using the scanner. Haven't tried driving it directly yet.

Now that I know my stepper motor, I need to drive it.
I'm thinking of using grbl on an arduino and a pololu TB6612FNG Dual motor driver. The specs say this can also drive a bipolor stepper, but I'm having a little difficulty finding info about connecting things correctly?

In other news, I just ordered some blue makerjuice G+ Because I LIKE blue (-=
So I can start testing exposure times with my projector. I'm hoping I can get by without mod'ing the optics. I'm willing to take longer to print if I can get larger prints, but I'll see what develops.

Now that I realise the Dual Motor driver WON'T work, I've ordered an A4988 stepper motor driver instead.
Should be here next week. That also gives me the option of down to 1/16th steps on the stepper. Once I get that, next week, I can measure the actual steps available with my scanner.

I started using a IN2104EP. I took out the UV glass from the bulb assembly, broke off the color wheel and added spacers to lens assembly to shorten the focus distance. I knew I needed to shorten the focus distance since I'm going for smaller prints. During the mods I stripped the projector down further than I needed to, all the way back to the DLP chip. The projector worked great on my bottom up setup, I was able to get decent resolution and cure times and ran several multi hour prints.

Then one day I turn the projector on and I get a LOT of stuck pixels. I'm not sure it was just the projector, me stripping it down the the DLP chip which could have effected cooling or removing the UV glass and color wheel. I'm doing this on a thin budget, so I've ordered another 2104 and will have it tomorrow. I'll do the same, remove the UV glass, color wheel and add the spacers. I may leave off the cover and add a fan to help cooling.

As a note, after the 2104 failed I got a Dell 1409x. I did the same process and after running for about 5 minutes smoke started coming from the projector. It started to melt and burn the plastic in the assembly behind the lens assembly. In the trash with that one. Giving the 2104 one last shot, otherwise I'll need to save for a proven projector.