Build Your Own SLA/SLS

Hey all,

After many many hours of testing my new bottom up LCD/LED based printer I have decided its just too much trouble dealing with part release from the VAT. I cannot get a successful complete print, part detaches from the build platform and this is with small parts and a FEP flex vat. I can only imagine how much harder it will be once I get to 400x300mm prints.

I will be switching to top down with floating resin. My concerns are with the wiper, is this needed? Im already using the low viscosity resin from Spot-A, its almost like water. Im wondering if I will have issues with layer control if I do not use a wiper.

Can people who have experience with top down chime in and tell me what they think? My assumption is that with the large vat I have, The problem with resin leveling will be greatly reduced. Perhaps just waiting a few seconds between layers is enough for it to level off?

Let me know what you guys think.

From what I've read and understand, there are several important factors in top-down printers to ensure consistent thickness of the layers. A heater in the vat can be used to raise the viscosity of the resin so it flows better. A wiper mechanism can be used in conjunction with dipping the object in the vat and raising it up to a level to wipe off the excess resin from the current level. After that, the projector exposes another layer and the process repeats. I have actually just received a prototype top-down unit from a vendor that I'm going to be working with over the next few weeks. I'll report my findings.

The problem I face is that my LCD needs to be close to the resin for it to work right. I dont have a projection lens so I cant project the image onto the resin. I only have a few mm of space between the LCD and resin surface so using a wiper will be difficult. I hate to have to change the system to be able to project the image a longer distance and still be in focus, that would make the machine much larger and much more complicated/costly.

Im hoping the large area, low viscosity resin and maybe a little heat will be enough to maintain proper layer thickness.

I've just started testing my top down and have been very happy with the Z behavior so far, no wiper. Just letting the resin self level works great

The wiper also helps to calm turbulence after the build plate has dipped.