Here’s a 0.05mm layer print in grey and clear for comparison. No real cleanup done, just rinsed and dried. (The little nubs visible on the grey one are from the supports-- they’re no worse than on the clear, but *everything* is more visible on the grey.) :)
Overall, the only real differences I’ve noticed so far is that with the opaque resin you can’t see what’s going on sub-surface while printing-- so any “oops” are only evident once the object is out of the resin (or done completely if it’s a small part). Otherwise, the little nubs left by the support structure tend to leave a little white stress mark if you scrape them off with a fingernail, so clippers and/or X-acto blade are maybe preferable. It does seem to be slightly less pigmented than earlier prints FormLabs had shown, but that could also be attributed to the thin walls on my test.
Other than the fact that I think I spilled more clear resin cleaning out the tray than I actually printed with so far and the fact that I got resin on my mirror (which I didn’t notice until *after* it was cured by the laser and fogged the mirror when I tried to clean it off-- *sigh*) the switch to grey was pretty uneventful. I ordered another resin tray today (and opened a support ticket about getting a replacement mirror). Trying to make do with one resin tray if you plan on switching resins more than, say, once is definitely not recommended by me…
Looks cool! Thanks for sharing these pics.
Sorry hear about the spill. I got a second tray myself to avoid wasting or spilling resin–it just seems like the practical thing. I’m also considering getting a second platform to use with the Grey resin but will probably wait until our printer is up and running again.
G.
Ok-- wow. 0.025mm with grey is pretty impressive. This has some print issues along the center axis (thanks to my now damaged mirror *grrr*…), but the top surface is pretty much flawless with that material and setting.
Wow! I can see the subtle angles and edges–amazing at such tiny scale. Can’t wait to try this myself.
Was the robot tilted during the print? Looks like a slight angle to me.
Also, can you tell me which way the long axis of the figure was oriented relative to the peel direction? Along the X-axis? Y-Axis? Somewhere in between?
Thanks for posting the pictures!
Yes, I had it at a ~12 degree angle to see how visible the layer-stepping would be on the flat chest of the robot. (Answer: not very!) Looks like I had it oriented such that the long axis was parallel to the peel. (I would have done it the other way had I noticed that. It would make sense that the more narrow the perpendicular to the peel axis the easier it should lift…)
Let’s see the support side of that robot please.
The support side is a bit of a mess, but in fairness I was experimenting with how small I could push the supports and a bunch of them failed which lead to some peel problems and laser scatter (above and beyond my damaged mirror). It’s odd how some things work just fine even without supports-- half the robot’s head is unsupported and worked fine, but where it lost a support on a foot there was lamination/peel issues.
I’m printing another one now for a more fair comparison-- I’ll take some better shots of that front and back. The support touch points do seem prone to causing considerable distortion though (especially noticeable at small scale), but again I’ve got mine dialed way back from default. Not sure how much that affects things, but I would think a wider support with a better formed ‘cone’ at the top would be better. I didn’t like that my support structures were taking more resin than the object, so I shaved things way back (1.5mm base, 1.5mm supports, 5mm spacing, .055 touch point, tip relative length 0.9). Might have to go with the more conservative defaults.
There does seem to be much more of a ‘pucker’ around the touch point than I remember on the clear, but it’s hard to compare since the clear is so tricky see vs. the grey. I suspect that on the ‘trailing edge’, resin clinging to prior layers is being (erroneously) cured as the small support structure is drawn. I’ll have to try at 0.050 thickness and see if it makes a difference. (Actually, I’ll do that with these next prints and post the comparison.)
I agree with you about the supports and the support tips. It is very strange that they chose those shapes instead of a cylinder support with a cone tip. For a printer that has such hard time curing sharp edges, all the supports and their tips have sharp edges that translate into over-curing of anything around them.
Supports close to each other fuse together. Support tips cause resin around them to be cured…etc.
I make my own supports for some of the models and they come out much better because they are round and the tips are cones. I get relatively sharp transitions from the edge of the support tip to the model.
Makes you wonder if there’s some patent regarding “conic tipped support structures” that they’re trying to avoid. 
Next print (away from the center of the platform where my mirror issue is)… The support side certainly seems uneven compared to the ‘face’. I would assume that it’s resin clinging to that side of the print and being cured by over penetration of the laser from the ‘face’ side? Maybe orienting the part at a steeper angle would help with that. (Thicker layers might too since it would limit the penetration of the laser a tiny bit more.)
I wonder if they actually have a current control on the laser diode to adjust output power or if they just step the galvos faster to reduce the laser time per unit area…
I would try printing this with the Auto-Orient feature, or orient at an angle like you said. For now printing everything at an angle is our only option.
Also try printing on the 100 setting.
The problem is that laser penetrates too deep and over-cures the past layers again. That’s why the surface is always messed up on the other side, especially when the model is printed horizontally like that.
Even when you angle the model the same happens, but you end up with a better looking model. The back is still distorted a little bit, but instead of those uneven bumps of resin, you get somewhat even linear deposits of cured resin on top of the already cured surface. If you have details on that side, you are out of luck, because they get smoothed over.
The only solution I see is a resin with a higher pigment, that will stop the light from curing past the layer thickness, and printing at the 25 micron setting using that resin. Right now when you print at the 25 setting, all it seems to do is fire the laser less or use less intensity, that’s why the difference between the 25 and the 50 is not that big. But I think we need different resins for each layer thickness setting to optimize the output quality of the prints.
If you are worried about the lighter grey marks from sanding or picking off the supports just drop it in the IPA bath again and give the spots a good rubbing. I sanded a couple grey parts now with great results and almost no noticeable difference in color after a second wash.