Alternative method for bottom-up curing - oxygen as curing inhibitor...

[taugusti]

Hi Rylan and Co,

I just found this page: http://carbon3d.com/
They present a technology that looks like SLA. They cure from the bottom which has been discussed in this forum also.
As I understand it, the really interessting part is that they use oxygen molecules to create a liquid resin layer between the bottom and the build object. Somehow this makes layes get integrated better (they claim).
It seems that they avoid the ripple and layering issues in this way.
They also present it as ground breaking :-) A tiny bit of over-selling perhaps :-)

I don't know if this is in any way something useable for the Peachy - but maybe it can inspire alternative solutions.

Best regards
Thomas Augustinus

[quertz]

Hey Taugusti,

Actually that method already gets used in a few different ways:
While normal bottom-up SLA printers have to move the whole print up and down again for each new layer, you can avoid this by not curing the bottom Layer completely.
To do this one can either make the bottom layer of the container from a special material that lets oxygen pass through or one can have a special kind of oil put onto the surface that you have to reapply before every print.
By doing this, they can print really fast, sometimes even in under 5 minutes
https://www.ted.com/talks/joe_desimo...was_25x_faster

As they have only halfly cured layers, they can bond together way better than with normal printers and have almost no difference in strength along the layers vs perpendicular.
But all of this still needs all the expensive parts the Peachy got rid of.

The ripple problem on thy Peachy rather comes from the sensitive mechanics and the fact that we print top-down onto a maybe moving surface.
But on the other hand the Peachy already uses the "half-curing-technique" because it is necessary as we can't move the surface of the fluid up and back down for the next layer.
Considering the Peachy can print in 20mins, they already are really close to those incredible print speeds!

Have a nice day,
quertz

[rylangrayston]

This might be an interesting read:
http://peachyprinter.ipbhost.com/ind...yers-are-made/

like querts said ... we are already using some of the techniques that carbon 3d talks about, to add to what querts said Ill take a shot at explaining the situation too:

thoughts on oxygen and its effects with peachy and carbon3d:

1. The earths atmosphere has oxygen in it so all of peachy printer prints from the very beginning have been taking advantage of having a layer of thin layer of originated resin that dose not cure as readily as the resin below it. In the case of the carbon3d the oxygen layer prevents the cured resin from sticking to the window... peachy dosent have that problem in the first place, but the oxygen layer we have on the surface still helps a peachy printer, because it helps the surface of the printed wall stay wet, which is good because the resin flows over a wet wall much quicker and with a thinner coating than it dose a dry wall.

2. One pass of our laser dose not fully cure a layer, each pass is more or less doing the work of curing the last 10 layers. Each pass dose add a layer but the newest layer is like gel, it needs more passes to cure it fully... the laser light penetrates many layers deep into the resin and so after many passes the layers are cured gradually. we think Oxigen helps this process as well. So this is a feature of oxygen that peachy printer and carbon3d type printers do share. ... but this is not new, all top down printers would have this feature.

The carbon3d might be novel and new because as they say they figured out how to get oxygen through a window. but with peachy we don't need to do that because we print on the surface where oxygen from the atmosphere is already present.

Every thing Ive said above it just what I think is true... I could be incorrect, and if so I would love to find out

[taugusti]

Hi Rylan
Thanks for the explanation - I did not think of the surface/air and the following easier "flow over"...
One question though - what happens if you are printing a horisontal part of an object? the top layer will only be cured once... Will the finished part have a soaking / soft / semi-cured surface on the horisontal parts?
/th

[CescoAiel]

First off, you need more than a single layer for a reliable horizontal plane, so the bottom layer will be cured a few times... Secondly, the model will continue curing once printing is done from natural UV, which you can speed up further by putting UV lights around it...

[harpo99999]

taugusti, the lower layers of the horizontal part will get additional uv exposure due to the partly cured layers above still allowing uv through while the fully cured blocks uv(from one of rylans previous posts

[taugusti]

Hi All,
Thanks for the explanation.
Looking forward to see it in the real world :-)