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Sil_x
05-18-2012, 04:12 PM
I have been thinking about this project and gathering parts for some time and I think I am ready to start building. Up until now the biggest road block was software but Printrun has a projector mode that works with skeinforge's craft output.

DLP Engine:
I plan on using a dlp engine from a dlp tv that was broken on craigs list. This should give me a larger print area than with a projector.

Electonics:
I am using an Arduino nano with teacup firmware loaded and a hobbycnc steper driver. The stepper driver has a blown X and Y but the Z and A still works which is all I need.

Materials:
1/2-10 acme lead screw
2x 18" 20mm linear rail
I am using corian since i have a ton laying around but plywood or MDF should work.

The opening in the base is 12"x9" and the frame is 18" tall so I should get 14"-15" of z.

Sil_x
05-18-2012, 05:17 PM
I had some 20mm linear rails left from an early router attempt. I tapped the ends for mounting. For the lead screw, I turned down both ends to 8mm and tapped one end. The other end I used a cir-clip and I used 2 608 bearings for mounting.

rpovey
05-18-2012, 09:57 PM
Interesting, what sort of epoxy are you intending to use?

Sil_x
05-19-2012, 12:20 PM
I plan on trying the solarez lovoc polyester resin. At 44$ a gallon its decently priced.

I did lot of testing on using a non stick surface on the bottom of the vat. I tested touch screen protectors and mylar which did not work and . I settled with adheasive backed FEP film from mcmastar carr. McMaster-Carr (http://www.mcmaster.com/#5805T11). Applying the adhesive back sheet without any wrinkles is extremely hard since the adhesive is supper sticky and you only get one shot.

I am also investigating into polyethylene plastic. Test curing on a freezer storage bag worked beautifully however I have not been able to find a clear adhesive backed source.

The bottom is made from 1/4" inch plate glass and the sides are 1/4" plexiglass. I used glass etch around the edges of the plate to help the plexiglass stick better. Its all glued together with gorilla glue and silicone.

Sil_x
05-21-2012, 11:06 AM
New progress, built the stage. The part extending into the vat will be 2 pieces of 3/4 corian. The rest is aluminum plate and a delrin lead screw nut

rpovey
05-21-2012, 11:14 AM
Have you thought about how your going to break the layers adhesion to the tank bottom?
I've seen a couple of mechanisms including tilting the build platform and more recently sliding the tank.

Sil_x
05-21-2012, 11:35 AM
Have you thought about how your going to break the layers adhesion to the tank bottom?
I've seen a couple of mechanisms including tilting the build platform and more recently sliding the tank.

I have seen some of those mechanisms as well, one that pushes down on the vat to pop the layer off and another that slides it back and forth. I am hopping that the FEP film will be non-stick enough that it will not be need. I did some adhesion tests before I started building and I think it worked out well.
I do have concerns about the cure depth. I might have to look into a UV blocker to mix into the resin.

BobWarfield
05-21-2012, 12:51 PM
Been very interested in seeing a build log for this style of machine. Thanks for posting.

Best,

BW

rpovey
05-21-2012, 12:52 PM
My concern would be that even with a nonstick base, you'll still have two mated flat surfaces, so I think you'll need some mechanism to "break" seal.
Either way I'm interested to see how it works out.

Phife
05-23-2012, 01:25 PM
Im building one of these next, im currently building a large format reprap style 3D printer.

A couple of things I have learned from the various groups and forums about the 3D DLP method is that the vacuum force that exists when you print a part on the VAT floor is very high, Your FEP film will not help release the vacuum, you need something to break the seal, I think the Sliding method along with some PDMS silicone on the VAT bottom is the best so far.

Also, from my research, I think that the Solarez stuff is not really suitable for this type of printing, too slow to cure. You'll want to go with one of the DLP 3d Printing resins that are now available from places like http://www.spotamaterials.com/ or Bucktown Polymers - The Future of Polymers (http://bucktownpolymers.com/)

They are made for this specific application and should work well with your setup.

Also, ive heard that the Castin Craft Resin dyes work well for coloring and for reducing the cure depth.


I have a few questions, you mentioned you were using the DLP from a TV, have you figured out the optics and light source?

Good luck with your build, check out the yahoo group on 3D printing for a ton of info on this method. I look forward to watching your progress!

Sil_x
07-04-2012, 01:44 PM
I have been busy with a different project so I have not gotten much done lately. Here are a few pics of my first attempt to print. Cure times and UV permeation is definitely something I have to dig into