UV leds, pwm and UV curing oven

3W Leds are bright little suckers, dont work around without eye protection. I brushed a 5v across a pair just to make sure they'd light and my eyes are still irritated an hour later.

I built a constant current LED driver source ala this instructable, I bread boarded circuit 1 just to test the led's and will connect it all together so I can do pwm of the power and vary the intensity.

I need 1 maybe 2 of these 3w LED's for the printer, and the rest will be turned into a UV curing oven for the finished prints. Memory suggests stippled aluminum sheet does a great job as a reflector shield it scatters light and has high reflectivity. A quick browse around online and I think I might go with a combination of thin wall material and cheap turkey roasting pans for a oven.

single motor printing and bootstrapping

I need to get z figured out first. Once I have a good z motion I can start trying to print small parts. If i can get either of my projectors to a size of 10cm x 7.5 cm I can get a .1 mm resolution and print my own connectors for xy motion and etc. if I have a long z motion already I can print larger parts so I am aiming for a specific bed size but will take whatever I end up finding at the second hand store to salvage. the z motion should be independent of the tank I use.

Ramblings on build chamber thoughts

Thoughts on the resin chamber;
light proof or uv proof min
simple interior I don't want resin able to harden anywhere critical
Must be resistant to salt water and plastic resins, I suspect this leaves stainless steel, glass (crock pot?), aluminum will oxide passivate so it will eventually stabilize in the salt water.
a method of managing resin level... like maybe the way a teapot is built with a narrow tube from the bottom, or since ardiuno can be a laser scanner build a rangefinder in to check the arbitrary level of resin.

a build platform with holes so resin can can flow through/around as the platform indexes maybe a chicken wire mesh

I think knowing exactly where the surface is isn't that important as long as its focused for the first pass. if I build a raft or support structure of some arbitrary height and start with an over cure then every pass after the over cure will be of a known z motion and the actual height could be calculated from cure volume shrinkage - z strut support structure displacement.

Haven't decided how to place the z screw for the platform but it will be outside the tank. some stability considerations... I should think about that more

Stuff I have ordered/assembled

I will add pics of it as it arrives, i mentioned earlier I bought too much stuff... lets say building a second printer shouldn't be hard...

1 Converted ATX power supply 5v at 35a, 12v at 23a max, I have spares to do this to as well

Power Supply I use for electro-etching

5 nema 17 steppers 78 ozin

10 stepsticks with heatsinks

1 aurdino mega2560 v3 + ramps + 5 matched stepsticks (that's 6 extra so far)

1 raspberry pi with too many goodies and a camera(octoprint path or just a hdmi interface)

5 3watt 400 nm leds

The lightpath and dlp from a 44nhm84 toshiba dlp television

 An acto dlp Projector the other option for a "printhead"

2 gt2 5mm gears

2m of gt2 belts

4 nema 17 steppers 58 ozin

1 9bulb 380 nm led flashight

Parts and pieces I gathered from a 20$ tv

Back of the Dlp with a Dvi-d(duallink) cable, power cable, lamp detect and color wheel cables

Optics

The light path just fire a uv LED in the little hole

The power supply for the tv

3.5 years later I'm considering this again with today's technologies

my current plans are;
I'm trying to mix the concepts of a sla device with plotter technology

Build a dlp printer with a mobile print head that moves on 4 axis xyz+ focus
The print head is to be a modified dlp projector or tv projection system with a base detail of minimum .1mm

Build area of 20.5cm*23cm*23cm
if I can focus in I can get better resolution, absolute minimum spotsize for 400nm and crappy optics with a numerical aperture of .54 is 770nm .77micron .00077mm or damn small... I remember reading achieving minimum spot size is very difficult, but dropping a zero makes it achievable. .0077mm or a little under 1000'th of a mm at this level of detail the print head is 1mm across I dont think this is achievable with my optics setup.At 100th of a mm resolution the image is 1cm across, this is my goal, but I will consider this project a sucess if I can get a full sheet print area. at .1mm resolution thats 10 pixels per mm or a 2x3 grid of 1024+768 pixels like in the tv I am parting out.

Like a standard SLA machine I will be lowering a platform in resin. the resin I am planning on using is makerjuice which is supposedly VOC free and will float on salt water. I think this is brilliant since the proposed build volume is about 3 gallons or ~400 but I can float a liter on salt water and print for 25$

To maintain a constant surface I think I will try with an overflow pipe attached to the bottom of the build chamber. with the Z platform in the top position I fill the chamber to some mark with super salty water and then add at least enough resin it oveflows from the pipe, then lower the platform to its start position. The salt water overflow should keep the surface of the build tank the same the entire time as the platform supports continue to be lowered in. I'm doing it this way to keep from having to build anything super complex inside of a tank that's under assault from salt water and resin could harden in.

I've ordered too many parts I'm not sure what all I will need I have a Pi and camera on the way to run octoprint with... using the hdmi output of the pi I plan on driving the video of the projector.

It seems from reading in #reprap I might want to use an arduino, the support of users makes problem solving seem easyier the pi is just newer.

I am planning on a variable print resolution as defined by the z axis print head, change size. I see some real challenges to anything involving software more  complex than printing images serially like  an inkjet does.
        I would like (not planning on pursuing yet) for the printhead size to optimize printing. for example back out and print a large area, zoom in and detail, type of thing.