I know there are lots of ways to create a post-curing UV chamber and there is even a main thread for it. However, I want to target one specific feature of UV post-curing: oxygen greatly slows the post-curing process, some people even dip the part in water to avoid oxygen, but what if our UV chamber also has a volume free of oxygen, or at least with very low levels?
A watertight UV chamber would be one way of doing it. You insert the part, fill it with water and turn it on. However it does not seem to me like a very elegant solution. I was thinking of doing an equally watertight UV chamber, but maybe with a flame to consume the oxygen inside? I did not do the calculations with ambient air to know how much of a flame you would need to greatly decrease the level of oxygen and you would probably not do it with the UV lamps or the part inside… Or would you? Maybe something cheap like a can with UV led strips and a lit candle inside to consume a bit of oxygen would be enough. What do you think of it?
Probably not cost-effective, but what about the vacuum sealers that come with vacuum chambers? Stick your part in that, line the inside with UV leds (like in the paint can UV chamber design), suck out the air and cure away…
No, you don’t want to draw a vacuum. That’s crazy. You want a cheap, inert gas. Nitrogen or CO2 would work well and ought to be readily available. Take the UV Curing Jar I posted about making, and leave the over-center toggle latch, hinge and gasket on the lid. Add an inlet nipple and an outlet nipple.
Insert model, turn on LEDs, close and latch lid. Open inlet and outlet nipples. Inject gas of choice through inlet and let it run for a minute, then close both nipples.
Is there a chance that CO₂ or Nitrogen also have a slowing effect on the curing reaction? If not, your idea is a really good one. What about dry ice? It is a cheap way to get a good flow of CO₂. A CO₂-based extinguisher too but it is too big and not easily reusable.
you can get oxygen free nitrogen gas in cylinders from welding companies. you can also get argon gas which is completely inert and won’t react with anything. i would try that. you get it from tig welding suppliers and it can be purchased in small disposable cylinders as well as large ones.
I just dangle a reptile lamp over one of the Form supplied containers full of water with a little detergent added so it doesn’t grow any algae. If I’m in a rush I use my laser pointer over the surface while it’s in the water, cures up in a couple of minutes.
How much faster do you need it to be? We used to water cure with our old UV system. But now that we have upgraded to a 54 watt UV source, we just rinse the part of alcohol, and cure. Its dry to the touch in a few minutes, and fully cured in about 30.
The biggest issue is not oxygen or the UV, but the alcohol. The longer you leave it in alcohol, the harder it is to cure, so it requires a more elaborate system. Keep it short - use FormLabs recommendations as the absolute longest.
CO2 has 2 advantages over Argon and Nitrogen. It’s much heavier than air, and it can be liquified at room temperature. The first means you can have a container that doesn’t have an airtight top and still keep much of the oxygen out. In fact you will need to have a way for the oxygen to get out when you fill with the inert gas, CO2 will tend to stay on the bottom of the container while the air leaks out the top.
Being able to be liquified at room temperature means it’s much cheaper to store it. Common paintball tanks are CO2 tanks and are pretty inexpensive. A new small tank for compressed Argon or Nitrogen is $100+. I think CO2 gas itself is a bit cheaper as well.
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