How did the wine glass work out?
The compression layers are the ones that are ālostā so the resin can cure and over cure to the build platform. Since the cubes are .25 x .25 x .25, you have the Z measurement at .251" The printer has maintained the Z height properly with any built in compression. I will have to run off a set of the cubes to see what my Z measurement is. But I am using a Form 1+.
The sticking / suction you see is just the release of the resin from the PDMS layer. Depending on the surface area, it will be non-existent to really obvious.
Do you have an āover cureā line in the Z axis of the parts? On a Form 1 / 1+, it exists from the first layer to approx. 5mm. If you have this, I gather it is closer to .5mm or 1mm max.
Ah. So you noticedā¦ I made a very nice hockey puck thank you for asking 
lol. I used Clear V3 setting for some reason. I was getting a little cocky after all the successes last night, so I thought, if Clear is the lowest power profile on the Form2, then maybe using Clear V3 would be that last little tweak needed to get the dimensional stability we are looking for. Turns out the part dislodged from the build plate, I donāt think it could withstand the peel force of the circular base of the wine glass (angled would have worked Iām sure). So when I got in this morning, I tried it again with Grey V3. Identical result. I got the cubes going with actual FL Grey V3 right now.
I looked at the cube and I think I do see a different looking band at the base. Looks like 0.5mm tall to me. That is probably the over cure line you are referring to.
So, with your help, I was able to determine to correct orientation of the cubes, and I had everything backwards. The X and Y are very stable and accurate, however the Z height is the one that is off, which, as you pointed out, makes more sense due to the compression situation. I changed the numbers in the earlier posts, and added post cure measurements as well. It looks like everything got a little bigger after curing. What do you think?
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I like those results!!
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For reference:
FL Grey V3
01.mm
1/4 inch Cube Test
Uncured
Z: 5.53 mm (0.2177 inches)
X: 6.24 mm (0.2456 inches)
Y: 6.22 mm (0.2448 inches
I donāt know man, thatās probably as close as it will get without being able to tweek .ini settings.
Whatās the next test?
- We are able to print small parts with good detail
- The accuracy seems comparable to FL resins for the small cube test
- Final part mechanical properties seem >= FL resins (hard, not too brittle)
Go for a bigger print? Try a different pigment?
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I think printing something cool that can be measured to verify accuracy would be a great next print. Maybe that FL test piece with the screw holes and such.
Then print it again to verify the results are repeatable.
Then I say a different pigment.
Awesome results!
Try the formtest as I linked to earlier(yes, just do the repair!). It will tell you a LOT about detail.
Then the next printā¦ Something big, with a large cross section.
My little brain was going round in circles, then I realized that in clear resins there is no pigment to prevent the light from ābleedingā in the previous layer, but they use some UV inhibitors.
Now, to my knowledge there is only one resin with an open source formula and it is the Ember Clear resin, which is pretty high resolution for being clear. The formula is Open Source and can be downloaded form the Ember website, so, to save time and hoping Iām not infringing any law, here the formula
PR48 Formulation (all percentages are wt/wt):
ā¢ Oligomer: Allnex Ebecryl 8210 39.776%, Sartomer SR 494 39.776%
ā¢ Photoinitiator: Esstech TPO+ (2,4,6-Trimethylbenzoyl-diphenylphosphineoxide) 0.400%
ā¢ Reactive diluent: Rahn Genomer 1122 19.888%
ā¢ UV blocker: Mayzo OB+ (2,2ā-(2,5-thiophenediyl)bis(5-tertbutylbenzoxazole)) 0.160 %
If we could get hold of the UV blocker, then we could adapt many other resins that over-cureā¦ no?
Any thoughts?
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I believe all the resins should have some uv inhibitor which they use to keep nucleation in control and create an exposure shoulder. Without that the light would continue to spread and over expose underlying layers causing loss of detail as the print progresses. Pigments are added more for aesthetic reasons rather than function. Some pigments such as red- yellow spectrum will block uv and require higher output.
Key to this is speed, intensity and spectral response of the material. Some 3rd party resins donāt respond well or inadequately to the 405nm and lean towards the 365 side.
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Quite difficult to buy these chemicals in small quantities. 
http://www.apolloscientific.co.uk/display_item.php?id=33331
this is the cheapest I could find. If by weight it needs 0.16%, then it needs 1,6 g per kg of resin, resulting in Ā£2.56 per bottle ,considering you buy the 25 g packā¦ though I believe it excludes shipping and tax, and it should be enough for 10-15 bottles.
Makes sense?
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This stuff is a little over my head, so Iām just asking questions more than anything. Here is the description for Mayzo OB+:
āBenetex OB Plus (7128-64-5) is a heat resistant, solvent soluble, chemically stable fluorescent whitener that provides brighter looking colors. It is used to offset the yellowness of a polymer and to yield a whiter appearance. Optical brighteners create brilliance by absorbing UV light, modifying the wavelength of the light and then emitting the light in a fluorescent fashion.ā
Do you think this description is referring to the characteristics of the final cured resin, or the resin in itās liquid state. Does it then seem like the Mayzo OB+ is acting as both an aesthetic enhancement as well as functional change?
I did several test prints over the weekend with the Bucktown 40 Black (drops), and while the printed detail and final mechanical properties seem to be within normal limits, I am having a heck of a time with build plate adherence. For the Formlabs test print (generated from SCAD), I can see the part is printing/curing correctly, but at a certain point it always detaches from the build plate. If I try printing a normal part with supports, a portion of the raft stays adhered, but a small portion detaches (so it is kinda hanging from the build plate) and I get a successfully printed part, but with pretty severe banding when the part became detached.
I have a suspicion I put 5-10 too many drops in, and now I am getting a slight under cure.
I mixed some more Bucktown Clear with 10 drops of Green Pigment (Green PolyColor from Brick In the Yard Mold Supply), and the new color looks pretty awesome. With the Bucktown 40 Black, the pigment settles after about 24 hours, and you definitely have to shake thoroughly to get the proper consistency again. With the green polycolor, the resin looks like Tough V3, even after 24 hours. It looks like the polycolor actually changed the resin color, if that makes any sense - not settling at all.
Do you guys think I should start mixing in a little more clear with the black to see if I can get better base plate adherence? Or should I start the same process with the Bucktown Green 10? Or should I start lowering the Z-Offset with the Bucktown Black 40?
Try lowering the Z first.
My little brain started to go round in circles due to your little brain as well. 
We are talking mostly about under and over curing. But thinking about it, that might not be fully the case with the photocentric resin. Yes, the dimensions are too big and with adding pigment, they come much closer. But the support of the hard resin come out of the machine very flexible. After a few hours of fun, they are like youād expect them to be.
So what you are suggesting is probably right. The laser is penetrating too deeply into the resin(causing over exposure), but as the print deforms during printing, the resin might be under exposed making it too flexible. It is something we cannot control with pigment as that in itself would make it flexible and brittle after printing.
So much food for thought. 
I already spent so much money on all these resins that iām hoping someone else is willing to try the material suggested by @Polariz3D
Just sent an inquiry to purchase. Not too expensive actually. I also sent an inquiry to Mayzo for the OB plus quote.
Bucktown Green 10
0.1mm
Grey V3
Looks pretty good, I can even make out the āFormlabsā on the wing of the butterfly. Cross-linked supports still look a little thick, but this is only 10 drops.
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When testing I would think altering the z-height would add an unnecessary variable. Wouldnāt be better to correct the exposure? IE first compression layers should be exposed more if the part isnāt sticking.
Would that make more sense?
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I agree. The only slight problem is that I have fairly carefully measured the amount of pigment per tank, and now that I have slightly over pigmented, it might be difficult to accurately add clear resin back in.
You also might be referring to altering the .ini file to increase the laser power for those first layers, but unfortunately I have no way to do that with the Form2. To be honest, I have no idea what the order of resin profiles are from least to most exposure for the Form2. The only thing I have confirmed is that Clear V3 has the least exposure.
@HTL had a wonderful write up regarding pigments, layer height and cure depth, and also some ways to test those variables. I was a little confused on his method, but Iām wondering if I could try to apply those techniques to this particular resin with the Form2. For instance, putting a layer of the resin in the tank, printing an STL directly to build plate, only let it cure 1 layer, and then measure the thickness and so on.
@KenCitron Any ideas on how to correct the exposure within the limitations of the FOrm2?
I appreciate your help!