3D printing Bayonet Rings

[salmon]

I have been playing with making a 3D bayonet ring. So far I am to this point:





It will fit into a 2.5" diameter polycarbonate tube that has a 1/16" wall. Very tight fit, so hoping that molding and casting will shrink just enough for it to go in a little smoother into the tube. Now working on putting in a o-ring. How much of the o-ring should be proud over the contact surface?

Then other questions come to mind. Will resin casting work for this? is it durable enough to use in a sub?

For sure I will test and see!

[thor]

Nicely done, Tom!!! I am so happy to see modelers grab onto the new technology with both hands and not shun it. I really believe the hobby will be much better off when modeling skills and capabilities like this rest in the hands or every modeler, not just in the hands of few individuals. It opens this hobby up to anyone who can master some basic CAD and programming skills. With this, the individual modeler's creativity is the only limit to what can be achieved. 3D printing levels the playing field and opens up endless creative horizons.

There are some resins that would be appropriate for this. A few of the slow cure polyurethanes would be suitable and then, also, some of the high quality, unfilled epoxies would serve well too. Check out BJB for the slow cure polys.

Bravo Zulu, Tom!

[Ralph --- SSBN 598]

I never considered this for models but I have made several quick connectors using PVC threaded pipe fitting where I would mark and cut the threads in several sections and then cut the opposing threads in the other.

Then I could cut most of the threads off leaving two or three to engage.
Worked like a cannon or rifle breech bolt. Just with less threads.

[Guest]

Where is the o-ring meant to go, Tom?

[salmon]

Andy,
I am going to use axial type seal. Later, I may try to come up with a radial seal.
So, I am looking at the 1.2mm o-ring with a 42.4mm OD. This size fits nicely on the flat surfaces I created on the female portion of the bayonet rings. I could go larger diameter, but the OD sizes becomes an issue for this 2.5" tube.
Any advice is welcome!
Thank you Matt!
Peace,
Tom

[bigdave]

Looking good so far Tom.

And resin is fine for the assemblies.
That's how Engel does it in thier new smaller subs like the 212. BD

[salmon]

Thank you BD!

[Guest]

I would use a radial seal. Axial sealing is worthwhile sometimes, if you're trying to seal a large tube and the inside finish isn't that great, but when making a custom two part seal, I would go radial every time.

[Guest]

Why a bayonet ring, btw?

[bigdave]

I would use radial seal too.
If anything it would be easier to open and close.
The axial is not as forgiving with uneven sealing pressure either.
I had axial seals in my Delphin sub but they usually leaked as I could not get equal pressure without overtightening.
My Tadpole uses axial as well and is prone to leaking if not adjusted correctly.
The seal compression is automatically adjusted with radial.
When I cut my seal groves I like to run about .020 compression.
Some like less some like more.
A lot of guys mold in the groves but I cut all mine to depth on the lathe as Lexan varies so much in ID.
But this is something you can't do with the bayonet assembly. BD

[salmon]

Why a bayonet ring? It began as a conversation on a site and then an excercise to see if it can be done. Now that I am working on it, it might have a use in our hobby.
Radial seal = 2
Axial seal = 0
I will continue playing.
Thank you!

[bigdave]

Never stop playing.
That's where the run is.
If it works, that's a plus! BD

[Guest]

Okay. Well I'd consider the following.

The bayonet latching points can be on the inside or the outside, depending on whether they show, get in the way etc. Two or three latching points is generally enough.

Unreinforced plastics have very poor strength compared with metals like aluminium or brass, so any parts that have to take a load should be generously proportioned.

[scott t]

Very cool Tom. So Axial gasket would be like what I see on a water cup with lid and radial is the typical O-ring found on WTC?
So this would be axial on this rv hose connector?
So what if you size it to glue to the outside of your tube?

[salmon]

Andy, Thank you.
Scott, you are correct about what axial and radial is. Yes the photo looks like it is axial. I was playing with inside for a smooth look, but if that does not work, outside could be next.
So, I have been asked by a couple of people what is this made out of. It is a powder based (gypsum) process. There is a post cure that I need to do to give it strength. The two I use are a thinned CA or the epoxy. The thinned CA is great for things like this (the small bust in his hand):

The printer does print in color.
If you are doing something with a little more stress. Epoxy works for strength. That being said, it is not something that you would normally use directly in production and is a messy step. I am testing a mount in the walrus to see if it will hold up. It was soaked in epoxy.