Yes, well they got this problem with deapth of cure with transparent resins, meaning that the laser/projector light will cure resin as far as it can penetrate it, so we need to use pigments and make the resins opaque to get good accuracy. But I have a plan fo that… I’ll “burn” the surface of the VAT coating with long overexposures, making a very thin milky surface wich will act like pigments and diffuse light so that it’s only strong enough within ~100um.
Next comes warping: gotta be careful how we orient and support the parts in the Layout, warping comes from shrinkage, it happens near the Build Table because polymerization creates tension between particles that pull on eachother from all around, the particles near the build table have nothing to hold on to and they are pulled away. We have to place support Base about 0.15mm to 0.5mm thick all around the model and avoid having thick and massive features near the Table. Try to use FunToDo resins on the Form1, they only shrink 0.5% cause they contain no solvant.
Next, holes from thermal expansion: polymerization gives up about 60℃ heat and inside closed cavities the expanding resin tries to find a way out so it pops a hole on a thin side and flows out pushing the resin that’s trying to cure there, so a breathing hole is formed and the rest of the print will be fine.
Next, you have limitations like you can’t print a solid object hollow inside like on FDM printers, you need to be able to empty the liquid resin inside and rince it with alcohol and water; print size, the B9 can be calibrated for more precision and with that we adjust some parameters but the max printable area is about the size of your palm… The B9 can shoot 30um pixels but that’s too thin to cure and stand so the smallest feature should be at least 2 rows of pixels, 60um. The new Form1 has a 70um beam diameter, non variable.
Then you have a gradient light, stronger in the middle and weaker around the corners of the printable area. In the Form1 you have the laser hitting straight up in the middle and in an icreasing angle around the edges and corners. This causes for distorsions and warping on the sides so the printable area is not 100% usable for precision parts, at least in the first 5mm of the Build.
The advantage of the B9 over all other SLA printers is its sliding VAT and the wiper. The VAT has a doubble bottom, higher on the printing (Open) side and lower on the Closed side so after each layer the Vat slides to the Closed side and the model slides off the High bottom and thowards the low bottom thus the Build Table goes up for the next layer without any succion. Each time the Vat slides, the wiper cleans the High bottom of any half-cured resin that might cause shadows on subsequent layers, it pushes the resin and exposes the PDMS coating to Oxygen wich prevents polymerization on the very surface and does not allow the model to stick down to the Vat, it mixes the solvants wich would otherwise accumulate in the same spots and polymerisation would suffer incresingly, it mixes pigments wich would otherwise settle down with time. So the B9 produces consistent precision throughout the Build. That’s all I can think of for now, bring up some more issues and we’ll compare.
Thanks!
