I'd also like to point out that in many professional top-down systems, the built tank is flooded with an inert heavier gas such as Nitrogen or CO2 to displace the O2. This is so the top can cure better. I am working with several vendors who are doing this.
-S
Carbon 3D
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Re: Carbon 3D
Well tell them to focus their projectors at just below the surface and they can get this CLIP effect for free.
I just dislike immersion printers because your build volume requires a LOT of resin.
I just dislike immersion printers because your build volume requires a LOT of resin.
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Re: Carbon 3D
Last edited by Hugues on Sat Mar 21, 2015 2:09 am, edited 1 time in total.
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Re: Carbon 3D
If you are doing a top down vat, the resin at the surface is inhibited from curing by the presence of Oxygen (per CLIP/Carbn3D). So if you focus just underneath that layer, you would avoid defects caused by miniscus, and gain the benefits of the Carbon3D "CLIP" method.
get a fish tank and divide into thirds
Barrier between left most third and middle goes all the way to bottom, but not all the way to top. This is the overflow.
between middle and right most third, the barrier goes all the way to the top of the tank, but is open at the bottom so the reserve tank is connected to the resin float tank.
Fill with salt water denser than resin. On the right most third, float your layer of resin.
Focus your projector just under the surface of the resin on the right most third, just under the oxygen inhibition layer. Start printing. As the arm and platform submerges, it will continuously push salt water out into overflow, while the top of the resin and the inhibited boundary layer stay in the same place. You have to do this slowly and smoothly though, as you don't want to stir the resin. But no seperation force, no tacky surface.
This is all hypothetical, but its interesting enough I will probably go out and try it with what I already have built. Although I worry some resin will be wasted, potentially very fast print speed is too good to not try it!
get a fish tank and divide into thirds
Barrier between left most third and middle goes all the way to bottom, but not all the way to top. This is the overflow.
between middle and right most third, the barrier goes all the way to the top of the tank, but is open at the bottom so the reserve tank is connected to the resin float tank.
Fill with salt water denser than resin. On the right most third, float your layer of resin.
Focus your projector just under the surface of the resin on the right most third, just under the oxygen inhibition layer. Start printing. As the arm and platform submerges, it will continuously push salt water out into overflow, while the top of the resin and the inhibited boundary layer stay in the same place. You have to do this slowly and smoothly though, as you don't want to stir the resin. But no seperation force, no tacky surface.
This is all hypothetical, but its interesting enough I will probably go out and try it with what I already have built. Although I worry some resin will be wasted, potentially very fast print speed is too good to not try it!
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Re: Carbon 3D
I can imagine the following difficulties with focussing below the surface;
a Gaussian beam is in focus in a range known as the Rayleigh range; for a 20 micron spot, at 405 nm this is in the order of a couple of mm.
so for to be out of focus on the surface you would have to focuss 1 cm below the surface
there is refraction at the interfaces between liquids, you could calculate theirs angles and amplitudes using Snell's law and the Fresnell equations
The cool thing you can do with these Teflon AF sheets, is that they allow you to solidify parts below the surface of the vat. You could grab a laserdiode cover it with Teflon AF, submerge it into the vat and you would be be able to cure something, while being able to prevent that your laser diode gets stuck to the part.
Before Carbon 3D, I wouldn't know how to do it.
The problem with laserdiodes is that they distribute their laser power over a small area. A grating light valve or DMD chip would allow you to distribute the energy. A too high power would kill the deadzone and your laserdiode would still be stuck in the vat.
I would like to know what the thickest layers is you can make in one continous illumination without moving and without getting stuck to the part.
a Gaussian beam is in focus in a range known as the Rayleigh range; for a 20 micron spot, at 405 nm this is in the order of a couple of mm.
so for to be out of focus on the surface you would have to focuss 1 cm below the surface
there is refraction at the interfaces between liquids, you could calculate theirs angles and amplitudes using Snell's law and the Fresnell equations
The cool thing you can do with these Teflon AF sheets, is that they allow you to solidify parts below the surface of the vat. You could grab a laserdiode cover it with Teflon AF, submerge it into the vat and you would be be able to cure something, while being able to prevent that your laser diode gets stuck to the part.
Before Carbon 3D, I wouldn't know how to do it.
The problem with laserdiodes is that they distribute their laser power over a small area. A grating light valve or DMD chip would allow you to distribute the energy. A too high power would kill the deadzone and your laserdiode would still be stuck in the vat.
I would like to know what the thickest layers is you can make in one continous illumination without moving and without getting stuck to the part.
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Re: Carbon 3D
You don't care if its in focus at the surface because the surface cure is retarded due to O2 inhibition. The layer is approximately 150 microns thick, and does vary by light flux, O2 conc, and photoinitiator type.
So there is some maximum light intensity you can't got above because otherwise the O2 layer is overwhelmed. What this does give you is since you are curing just below the surface, you get no defects caused by meniscus. You need to submerge slowly to prevent disturbing the O2 inhibited layer, but per carbon3D and CLIP, this is still a LOT faster than curing against a vat film surface, having to lift to peel, then reversing direction.
So there is some maximum light intensity you can't got above because otherwise the O2 layer is overwhelmed. What this does give you is since you are curing just below the surface, you get no defects caused by meniscus. You need to submerge slowly to prevent disturbing the O2 inhibited layer, but per carbon3D and CLIP, this is still a LOT faster than curing against a vat film surface, having to lift to peel, then reversing direction.
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Re: Carbon 3D
Check out TPX from Mitsui Chemical, UV Transparent, Oxygen permeable, release force from Epoxy unmeasurable
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Re: Carbon 3D
Also available here $15 for a 12x12 sheet
Edit: never mind 1/3 that price on cshyde!
Edit: never mind 1/3 that price on cshyde!