Build Your Own SLA/SLS

Looking great!

How does the stainless steel compare to the solid AL buildplate? I'm still hesitant which solution I should try first. Did you roughen the steel plate?

Greetings from Berlin

Hi Kilh,

From my experience you have to have holes in the build plate if you use a flexvat (Solidator seems to be the exception). Otherwise the pressure of the buildplatform to the flexvat floor is too high and the floor starts to bend.
Also if you use a very thin build platform very little resin can stick to it. I had a aluminum build plate 10mm width before and half the vat resin sticked to it Stainless steel with 3mm holes is perfect from my point of view. I sanded it
and the models are sticking very well to it.

Greetings from Cologne

Interesting.

I have a 10mm thick build plate, and yes the resin goes on top and i need to clean it. But as the surface is smooth on all sides, i "scrape" the resin away with a silicon spatula, like the one we use in the kitchen.

With holes, how do you clean it when finished printing ? Don't you have some resin sticking a bit inside the holes ? Just curious.

Hi Hugues, most of the resin simply drops by itself. Most of the leftover resin can be removed by simply blowing through the holes.

Hi,

just a quick update, since I'm at a point where 99% of all the print attempts succeed. There was a lot of trial and error involve and of course a lot of resin Couple of things that I'm sure a lot of you know already, but I wanted to summarize my experience anyways. Maybe it helps somebody in the future.


FlexVat:

1. Since I'm using a relatively big FlexVat (24x16cm) the tention of the film is crutial to avoid sagging (having a printout with "bend" layers). As many members mentioned before. The sound of the foil has to be like a high pitched drum.

2. It's very well possible to use white PTFE foil (0.1mm) instead of the much more expensive transparent FEP-film. Don't use more that 0.1mm thinkness. The details get lost.


Building:

1. Check if your projector projects "straight". I think that most projectors (at least my BenQ TH681 and an very old Acer I had) project a little bit "up". I didn't notice while building and had to reconstruct the projector mount

2. I thought I could construct my printer as a "final" product. But at least for me I had to change quiet a bit. So I think that you shouldn't spend too much money on the first build


Printing:

1. With an build area of 19.20x 10.80cm (100 microns x/y resolution) I have an distance of ~20cm between the projector and the vat bottom. That means that the exposure time is quite high. I had to try out many settings, till I got it working. As a reference: using Fun To Do resin Standart red (which is awesome btw.) I use an exposure time of 5000ms (12500ms for the first 3 layers).

2. I had to add an extra waiting second between the build plattform coming down and the projector starting to project. The time is needed for the resin to "move out of the way". Otherwise it can easily happen that by accident the layer width is too think or air bubbles appear that cause the print to fail.

3. Take care of the z lift and retract speed. There's great potential of saving time there. Currently I printing at 300mm/m lift and 400mm/m retract speed. I had to put the lift distance to 6-10mm though (specially with larger prints).
For now I can print a 0.1mm layer in ~10 seconds (36mm/hour) with good results at 100 microns x/y.

4. I had to learn the hard way that the exposure time increases the more color pigment the resin contains. Printing black FTD resin with a layer height of 0.2mm took 15000ms per layer! Transparent and white resin tend to overcure if the exposure time is too high. All details will vanish.


Misc:

1. Specially with large and high prints (long printing time) it's very important to include a shutter into the printer from my experience. At least my DLP projector still projects some light to the black areas. Meaning that there will be a thin hardend layer at the bottom of the vat. And this layer can destoy the print. I used a regular servo (SG90) and attached it to the Ramps. I had to switch from Sprinter firmware to Marlin, which supports servo G-Code (M280). In Creation Workshop I added the commands to the G-Code and now I don't have any problems with unwanted curing.

2. I made very good experiences using a stainless steel build platform (sanded the surface for good sticking) 2mm thickness with 3 mm holes in it. Of course you see the hole pattern of your print, but it can be easily sanded away. The big pro is that the bottom of the vat doesnt get stretched by the force the build platform produces moving up and down. Also very little resin sticks to the platform after the build.

I hope that helps and please correct me if I told something wrong, or if anyone has made different experiences.

best regards,
Matthias

Thanks for sharing your experience.

Am I correct that your vat is fixed (no tilt, no movement) and your FEP film does not lay on a glass plate or anything else ?

Yes, exactly. Just a tentioned film.

That is one good looking printer! Do you mind sharing where you got the stainless steel net?

Thanks, I bought it at a local shop (Bauhaus, Germany)...

Awesome summary Very much appreciated.

kind regards from cologne