I had a notion today about how, on your next printer, you could enhance the life of your expendable tanks (good for consumer, ??? for the company).
If the resin tank is positioned on a 2 axis motorized system, you could conceivably allow the tray to relocate (or circle, or twist, or change quadrant, etc.) after each print layer to a different spot on the PDMS. When that layer is done, it would move to another location to start the next layer. I would imagine this would allow for a more even usage of the tray (and less unnecessary waste!) Once the part is finished, you could then have the tray start at a different location for the next part and prevent single spot wear from occurring on the silicone window.
I also just realized (after reading another post about orientating the axis of parts with respect to the peel motion) that the 2 axis setup could also allow the peel process to automatically change the angle of peel to maximize print capability and even out the stress direction on the part!
Perhaps a simpler feature that could be added to current machines is that the the Dashboard could keep track of where you have printed parts so far on each resin tray. That information should be attainable. Then you will at least know where you have worn areas and where they are not worn and can layout your next prints appropriately.
That’s a great idea as well. Even could program the auto-position feature to move the part to a place least likely to fail. Doing it from the software side of things would help the current printers.
Adding the moving feature with the 2 axes would spread the layering evenly across the bed and my guess would be that it would greatly extend life. Doing that would basically print 1 layer in one spot, and not return to that spot for another many layers. In the meantime, the silicone could breathe and result in less clouding.
That would have some issues though, since the layers can go down to 25 microns, that’s a very very small amount and any variance in the level of the bottom of the tray or slight differences in the X/Y motors would possibly cause a print failure.
One idea I had that might help in a number of areas–you could have a wiper that extends from one side of the tray to the other, and as it goes across it pushes away all of the resin but it is a little bit higher than the bottom of the tray so it leaves behind a very thin layer of resin. The layer prints using this thin layer, and then the wiper clears the bottom and then lets the resin fill the print area again and it wipes across to leave another thin layer.
This would probably increase the life of the tray but also would improve print results because the print would not be submerged into the resin all of the way so it would reduce the chance for the light to bleed through the resin and cure material on the underside.
Another method is the one that is used on the Carbon3D printer–an oxygen-permeable material is stretched across a hole in the bottom of the tray, oxygen goes through the material and goes into liquid resin on the bottom of the tray. Oxygen prevents the resin from curing, so that creates a thin layer of resin on the bottom that won’t cure. Since there’s a layer of liquid resin between the print layer and the bottom of the tray it means the print will not stick to the bottom and there’s no suction. The printer then can print continuously. That means the tray will also last forever pretty much since the resin isn’t curing on the bottom. Only issue is that the Carbon3D printer has a really really terrible pricing scheme, and I think their technique is patented.
The carbon is really cool and does have an incredulous pricing scheme.
The problem I see with the wiper is that due to convection currents and other flow issues, the thickness of the small resin layer is unknown and probably inconsistent across point to point. Also, where does all of the resin get pushed to and held? It would have to be hermetically sealed wiping, which isn’t impossible.
What if the silicone layer were more rigid and ground, such as a gas-permeable glass? The variance in height at that point would likely be negligible, since the surface grinding should maintain a sub .001" flatness tolerance. Hardest part there is probably finding a permeable rigid material.
It doesn’t matter if the thin layer of resin is uneven, you can’t make it the thickness of a layer due to the viscosity of the resin and surface tension, but having a thin layer will be of great benefit anyway. The main purpose is to avoid the print getting submerged in the resin over and over again. I wonder if it might also be possible to have some fans blow on the print to maybe get more excess resin to drip off.
The wiper wouldn’t need to have a perfect seal, if a little bit of resin slips around the edges it most likely won’t flow fast enough to mess up the print. The tray would have to be big enough to push the resin to the side.
I think with some testing, someone will be able to find an optically clear material that won’t go cloudy and wear out like the PDMS. Ideally we would get a solution like Carbon3D where it wouldn’t need a layer separation process and could just print continuously.
You could use something like an optical glass or fused silica. Those are very transmissive to the wavelength of the laser and would not degrade.
The only concern would be the wetting angle for the resins.
The difficulty in implementation would be figuring out how to match the geometry of the existing tank and designing the rest of the tank to seal around the optical glass.
My Form 2 is supposed to show up today. I’ll have to think about whether it makes enough sense for me to try and design a replacement tank or just keep buying the consumable.
Sounds like a good idea for material change.
I wonder if the refractive index of the optical glass and/or silica would affect the laser path…
I am curious if the tray coated with a PTFE spray would work. Or a Silicone based Mold release (Parifilm or Ease Release) I use it on my Milling Bits to help prevent sticking when when milling soft Alum… May try it directly on an old tray once I have a worn out one, The only issue I can see is how to compensate for the difference in layer height once the silicone is removed…
The $60 tray doesn’t hurt my feelings on production as my time is more important the the few $ I will save on recoating/pouring a replacement Silicone Layer, (Cost of doing business and I just to pass it on to the client or the cost of the kit. I design and Produce Scale Models for the hobby industry)
it is more of a curiosity.
I’m wondering if the PTFE spray coat would repel the acrylic resin to a relatively set height as well as resist the laser wear. If so, it could be similar to the effect given by Carbon3D’s oxygen permeable layer. That could also really enhance print speed if it worked!
Please test it out and come back with the results if you can!
I wonder if a suspended sheet of transparent graphene on the bottom of the tray would work? Expensive probably.
areffelt If the Carbon3d had a cast-able finished product I would have bought it instead of the Form2. And yes that price is crazy but for what I do it would be worth it to get models that fast and smooth ready to cast.
If you’re willing to spend $40,000 rent for the Carbon3D printer, you would be better off just paying $50,000 for one of the wax printers that uses a support material, then you wouldn’t have any cleanup required and you would own the printer.
When I first got into 3D printing, I was under the impression that the resin was cured when lasers of 2 different frequencies intersected. At least that’s what the videos seemed to be showing, and possibly even saying. Maybe non-techies were just guessing, or they were talking about the year 2050.
But that’s not how Form 3D printer works, and I don’t know if any of them do work that way, actually.
But doing it that way would eliminate the peel or wipe though. In fact, you could eliminate a lot of the support structure too, if the lasers were on a multi-axis rack (like the CNC subtractive racks), so it would more similar to a person walking around a structure adding clay, instead of everything being done one layer at a time from the bottom. That’s where the horizontal stuff become impossible without supports. Ah well, maybe for the Form 5 …
I’ve also wondered why PTFE isn’t used. Is the silicon better somehow?
If the lasers intersecting was a thing, then that could possibly work to make an object in the resin, though it would possibly have some issues due to the print blocking the laser as it gets built. In any case, I don’t think that’s a thing.
An alternative is to reverse the print process, have the laser point down and move the print down into a vat of resin and print on the top surface. Faster, but has many other issues. That’s how that one printer–Peachy was going to work, but that was probably the worst implementation of that method I’ve seen.
If my PTFE idea doesn’t work(which I don’t think it will due to it wearing off after a few prints then having to clean and reapply is way to much of a pain in the rear) I may give this a try also. Might be nice to be able to just peel and replace…
Will try a smaller sheet if it works then buy a larger sheet then just cut multiple replacements… May cut the tank costs in 1/2 anyway.
Maybe The FEP could go right over the existing layer of silicone in a new tank to just preserve the life.
I was under the impression that preform did this (auto-repositioning of the part to increase tank life), but then I discovered it does not. Also, I can’t move the printed part. There’s no translate feature, which is super lame, and pretty ridiculous that it was never implemented. It’s one of the simplest features they could add.
You can move parts around, off-course. Go to the “Layout” menu, choose the part and drag it around.
It says the FEP has a low tensile strength, just a heads up. It probably won’t matter considering the low force the machine actually applies along the shear plane, but still.
Why wouldn’t regular old glass work?
There was a guy making some tanks with glass but now he is not responding to requests or emails so I don’t know what happened there,
But I have a feeling the resin was not releasing from the glass properly… I know this isn’t a good comparison as it is comparing apples to oranges but I use a lot of Plate glass for mold boxes,bases and flat castings to keep my molds perfectly flat and dimensionally stable when using polyurethane resins and after a few uses the resin will really stick to the glass as to where I have use a razor scraper to get off with a fair amount of force. So when I use the glass for the flat cast I have spray it with a release agent or coat them with Canuba Wax to aid in release which in the printing world would first be a major pain to clean the tank out every 3 or 4 prints to re-coat and I could see the coating or any micro imperfections in the glass causing the Laser/Light to diffract making the prints soft or fail and buying a true optically clear perfectly flat piece of glass is not a cost effective option as the glass would cost more then what we pay for a replacement tank now.
I saw the FEP has a low tensile strength my line of thinking (Like you said) if the resin does not stick to it it won’t matter.
All these ideas are just that, Ideas… and will play with them in the spare time (Like I have a lot of that ) It is just out of more curiosity. I am one of those people that looks at something and thinks… Hey I can make that vs buying it and will spend $200 to make a $60 part…
Then you’re the best kind of person! No progress without risk and attempts.
It’s too bad we can’t add a super viscous liquid that the resin would just sit on top of. Pretty sure that would have the same effect as the carbon 3D. I was trying (briefly in my lunch break) to find a clear material that acrylic dislikes, but came up short. I did stumble across transparent aluminum however!
Ah well, maybe someone else has another idea!