Three Layers of Liquids for Higher Quality Prints

[jstrack2]

The vibrations cause the fluid to move only at the surface where the resin is. Obviously the resin can not be at the bottom since there will be no way to raise the level of the resin. However what about having three layers of fluid? Salt water would be on the bottom as before, resin in the middle and some liquid lighter than water at the top. A tube could have one end at the bottom of the container to directly inject salt water without disturbing the middle and bottom layers, and so that way everything would work as normal. Of course this lighter than water liquid would need to not mix or react with the resin and it must be totally transparent to the laser.

I tried mixing soap (bottom layer), dyed blue water (middle layer) and olive oil (top layer) to try it out and it definitely stops the middle layer from shaking unless the glass is really vibrated hard (like slapping my hand hard against the table right next to it). Here is a hardcore version of several layers: http://img.wonderhowto.com/img/origi...8232920665.jpg

20140520_140753.jpg

[Feign]

I would worry about refraction/diffraction of the laser through the top layer as its surface ripples. Also it's possible that resin is oil soluble, what with most monomers being oil-based, which would mess up the whole thing.

[jstrack2]

I would worry about refraction/diffraction of the laser through the top layer as its surface ripples. Also it's possible that resin is oil soluble, what with most monomers being oil-based, which would mess up the whole thing.

To deal with the ripples the laser could hit the bottom of the container and shine up.

As for compatibility of the resin and third liquid I don't know much about this at all, but it seems some combination could probably be found. I don't think that it has to be totally insoluble to work though. In my example picture I had dish soap and water and they stayed pretty separate. If the resin isn't significantly reacting with the third resin I think that it might be okay.

There might be a another option I can think of as well. If the density of the resin is greater than pure water (but less than salt water), then maybe pure water could be carefully added on top of the resin, and have the salt water below the resin as before. More and more salt water would then be added just like before to raise the water level. Of course plenty of resin would have to be used to prevent mixing of the salt and fresh water. Then again it is probably always good practice to make sure there is enough resin.

There is the issue of refraction though. If the laser is sent through the bottom of the container the container's bottom thickness will need to also be known. Also the thickness of the saltwater will be needed, but this is already going to be known. The refraction indexes will also need to be known, but this is probably easy to look up. After that this information will need to be entered in so that the software can do the simple trigonometry to correct for the refraction.

I agree that this makes the Peachy less simple, but it might be worth it. Maybe as an option. It would eliminate any ripple problem. This would allow for better prints, even in slightly shaky environments.

[jstrack2]

I found out that the density of the resin that was used before (and maybe still now I don't know) was 1.052 g/cm3 (at 25 C). I don't know what the densities of the flexible resins are, but this would work as it is greater than water without salt and less than salt water.

Am I missing something that would prevent this from working (or make it not worth it)?

[Feign]

If you shine the laser up through the bottom of the tank, you would need to have the water level drop rather than rise and have your anchor mesh suspended from the highest point of the water level. At that point, the third layer is superfluous.

Also, salt water attenuates UV rays much more than air (if not outright blocking them), meaning your laser strength would be much higher at the end of the print than it was at the start.

[Anuvin]

I have had fairly large bubbles come through my hose, and I am never even remotely careful about hitting my desk, and I believe that not one single problem has arisen because of it. I do not believe ripples will be a problem in the long run. A very thin top layer might help though, and is certainly worth a try! All someone needs to test this is a laser in the 350-420nm range.

[Feign]

All someone needs to test this is a laser in the 350-420nm range.

I just so happen to have gotten one of those in the mail yesterday! I'm still waiting for my MakerJuice order to come in the mail though. Once that does, I'll be doing much testing. I wonder if a thin layer would still deflect the laser significantly and if so, would that would be more or less destructive than the vibration dampening properties on the resin's surface.

Despite those questions, fixing the software is definitely the priority right now, I agree.

[jstrack2]

Feign, good point about the water level dropping instead of rising. This may be a bit easier since salt water won't have to be elevated above the already elevated container. Hopefully having the mesh near the top won't be too difficult to set up.

I disagree with the other two points though. A third layer of liquid will still be desirable since as the level falls the resin would still ripple without the third liquid layer. It is no different in that regard to the normal way of having the water level rise.

As for light attenuation this is not true. I think the laser being used operates at 405 nm. This is actually very close to the wavelength where the salt water is most transparent.

http://www.obs-vlfr.fr/LOV/OMT/fichi...t_al_LO_07.pdf

If you scroll down to eighth page, you can see that in salt water (at typical ocean concentrations of 36g/kg and 20 degrees C) the attenuation coefficient is 0.0046/m from the water and 0.0065/m from the salt. Since light falls according to the Beer-Lambert law, Iz = I0*e^( αz), 20cm would only attenuate about e^(.2*.0046) + e^(.2*.0065) = 0.22 percent. I don't know how salty the water being used here is, but as you can see it won't make much difference. If the laser went through a large amount of water then this effect could be corrected for by having the laser move faster and then turning off briefly for each layer when the water level got close to the bottom. But honestly I don't think it is an issue for normal use.

[jstrack2]

I definitely agree that water ripples are very far from the biggest problem currently, but I think that eventually it could limit the print quality. I am very excited to hear the results of the testing!

[Feign]

As the level falls, the resin would ripple, but it would ripple along the top surface, while you would be printing from the bottom surface.

As for attenuation in water, I clearly have been told. With math! And a good point about being able to adjust the exposure time from the software, I didn't really think of that.