3D Printing improves degassing

So, Degassing is the process of getting all the air out of the mixed resin. This leads to stronger parts with a better cosmetic finish – you aren’t fighting tiny bubbles that appear in the resin, or that start to appear as the resin warms through the exotherm and the gas expands.

It’s simple to do – you put the resin in a chamber – evacuate it and watch the resin bubble up as the air comes out. As the bubbles near the surface, you let a little air in to equalise the pressure, the bubbles subside and you continue until under full vacuum, no bubbles appear.

However, it’s NOT SIMPLE TO DO: I lied. There are subtleties to this, and if you just open the tap carelessly,it’s easy to let the air in too fast and get resin everywhere. Also, you end up shooting air into the resin you were trying to clear of the damn stuff. This is also how you trash a degassing chamber, and they aren’t cheap.

The following youtube video I made illustrates this with water. Read on to see how I fixed this with a simple 3D Printed part.

So, I designed and printed a part that moved the air and vacuum over to where it was needed:

So, using some gum-tape to fix the air-guide in place, I now have a degassing chamber that lets air in without worrying about shooting it back into the resin.

Making a vacuum manifold

I suppose your first question is “what are you even on?”,  and your second question, is “why bother?” If you need a vacuum manifold. Well, to answer them in order:

  1. I am on a chair, in my office.
  2. If you want to double bag, or hold down vacuum whist you degas, isolate a catch-pot or pat your head whilst rubbing your tummy, you need a vacuum manifold.

I mentioned making this in the infusion stations post and showed how I’d connected it to my vacuum reservoir, also known as “my old compressor tank”.

Basically, I’d hoped this doodad that I’d wombled off eBay would work (it’s a CO2 gas splitter with valves for the unclicking) and hoped it would fly straight out of the packaging, but it turns out it has non-return valves in, which means it won’t work for vacuum. 

I tested it against my vacuum gauge and it’s great – seals well and holds vacuum both ways.

Here it is, in the vice after I’ve taken it apart to see what gives with the valves, and can I somehow get them out.
They were only turned in with PTFE tape, so were an easy extraction. It’s worth noting that the steel is either polished stainless (probably) or chromed. Either way, the finish was great.

If you look at t’photo ont’ right, you can see the on-return valve, and as I hoped (but didn’t have a clue about before I dismantled it), the housing for the valve (ball on a spring) is a press fit. All I then did was get the right sized drill in there, and started drilling it out. Sure enough, it went pop, and the whole thing turned out.

Here it is, open and ready to go. You can easily see through to the white foam I used as a backing material for the shot.

 And the the detail-obsessed amongst you, here is the spring, cap, o-ring and ball to seal it. Very neat and simple.