3D printed internal valve trial

[mmk8283]

Hi Everyone, I'm relatively new here, and previously posed this to the bleacher-reacher thread. I thought it might be more appropriate to make a new thread dedicated to my experimentation with a 3D printed internal valve. I'm open to everyone's thoughts and suggestions, and I will answer as many questions as I can. I will post updates as I go along.

Some Notes so far:

1. I'm using PLA (its all I have right now)
2. The rear port will lead to a 1/4" npt bulkhead fitting through the side of the 3" PVC chamber. and then into a manifold for filling/exhausting/pressure relief/gauge....etc.
3. Piston face is currently adhesive backed neoprene, I plan on switching this to silicone rubber.

[Moonbogg]

I think the valve looks great. That looks like the kind of thing I would design myself and I like it. I haven't studied the valve closely, but it just looks good generally. I wonder how strong the plastic will be where those small screws are. The only real concern I have is you mentioned something going through the wall of the PVC chamber. I'd just worry about the hole weakening the chamber. How much pressure?

[mrfoo]

Bearing in mind that I know bugger all about 3d printing apart from what Ive read on line, I think I'd probably be a bit worried about the housing splitting along the lines between layers. Otherwise, it looks proper good and very much the kind of thing I'd machine.

[mmk8283]

I'm only going to be dealing with about 40psi max.. which puts me around 280lbs of pressure on this. At this point I'm still testing concept, and it could likely be made from aluminum if need be. With the piston itself being 3D printed, it has very low mass and hopefully will not create too much impact to destroy the carrier or end cap.

I attempted assembly this past weekend... unfortunately the inside of the PVC is much more out of round than I anticipated... which resulted in the O-ring not creating an airtight seal. I'm going to be changing the design to accept a cup seal for my next attempt. I may also play around with a heat gun and a mandrel to form the PVC to be more concentric in the mean time.

[jackssmirkingrevenge]

Looks good, but I'd be really concerned about PLA both in terms of strength and impermeability. Perhaps saturating it with epoxy would be a good idea, or printing a hollow shape that would accept an epoxy pour.

[mmk8283]

Looks good, but I'd be really concerned about PLA both in terms of strength and impermeability. Perhaps saturating it with epoxy would be a good idea, or printing a hollow shape that would accept an epoxy pour.

an epoxy pour is a great idea... I will keep that in mind. My biggest roadblock right now is that my PVC is far from concentric, its giving me grief on the o-ring seals. I'm waiting to test a cup seal design... I'm just a little short on time at the moment

[Moonbogg]

A cup seal might work, or you could use an oversized X-shaped o-ring and have it compress more than normal. It might fill in the gaps. Have you tried a different piece of PVC pipe? Another option might be to use a hose clamp around the PVC pipe to force it to conform to the piston housing. If the pipe is egg-shaped, maybe it can be made cylindrical by clamping around it?

[mark.f]

Perhaps saturating it with epoxy would be a good idea, or printing a hollow shape that would accept an epoxy pour.

*buys 3d printer*
*uses it to make epoxy molds*
Typical.