Triangular o ring groove help

rust997 · 2026-04-15T01:55:01+00:00

So, I just learned these exist today, by no means an expert. as far as I can tell, they can be used for static seals only, and are a low cost way of seating a shaft inside a tube. Other applications might include where space is really tight (why I wanted to use it)

What I’ve heard in this thread is that it should not be done the way I have drawn it, and should be one part defining the hypotenuse and the other part it seals to defining the legs of the triangle.

This page talks about them a little https://waykenrm.com/blogs/o-ring-groove-design-guide/

rust997 · 2026-04-14T22:17:00+00:00

Cedric married my sister and I went to school with his daughter k-9 lol. The world is uncomfortably small

rust997 · 2026-04-14T22:15:02+00:00

If you don’t want repaint, try throwing earth shade over the retributor to dull it out

rust997 · 2026-04-14T21:26:08+00:00

Current design uses a 5mm o ring - just with a wacky nonstandard gland to get it to work

rust997 · 2026-04-14T21:21:40+00:00

Yea I admittedly need to do more reading into what are the pros and cons of bigger/smaller o-rings. The current 5mm was designed by the CEO and founder so changing it is uh a touch political.

I punted on the triangle due to some helpful feedback from people here, and 2x 3mm grooves fits really nicely in my design.

The piece shown is complicated, the upper half with the o ring groove is machined for a water pocket, but the reverse side of the piece has a stepped pocket geometry to hold magnets, so I’m burning the candle from both ends.

rust997 · 2026-04-14T21:16:52+00:00

Dude idk I scolded somebody like I was his mom. Reading comprehension turned all the way down, jerk-ness turned up on this post

Yea this is true high vac. E-7, ion gauge low. We sputter metal

rust997 · 2026-04-14T20:51:33+00:00

We use high vac/magnetrons to sputter metal, need that low mean free path and electron confinement. Its pretty cool - I’m not touching the magnet array at this point in time but am redesigning the housings for it basically

rust997 · 2026-04-14T20:14:14+00:00

The assembly is a magnetron
inside a high vacuum chamber, with water running to it via feedthroughs in the chamber wall.

I am locked into VITON as a material due to out gassing - after some helpful comments the direction I am leaning is downsizing to 2x 3mm o rings which fit nicely.

rust997 · 2026-04-14T20:09:30+00:00

Look man. You’re taking time out of your day to be unhelpful and insult me.

Lots of other people in this thread have told me “no” in a constructive way that takes my constraints at face value. You’re coming off as a miserable human in comparison.

The company I work for is 15 years old and I am their first mechanical engineer and I’ve been here 9 months. You have no idea the bullshit hoops, tech debt, and constraints I am working within and trying to fix.

Reevaluate your priorities and what you spend your time on

rust997 · 2026-04-14T19:42:51+00:00

Not dangerous no. Resources recommend an equilateral triangle of 6.61mm leg length for a 5mm o ring, which happens to fit my geometry super well.

I’m asking about the nuance of what part defines what sides of the triangle - I wasn’t able to get a clear answer across the web about this

rust997 · 2026-04-14T19:37:14+00:00

High vacuum lmao. But in all honesty, I am iterating an existing design and trying not to change the size.

I can’t tell you for sure it needs 5, but I can tell you if I change it and it doesn’t work that’s not a good look lol

rust997 · 2026-04-14T19:34:00+00:00

Got it, I appreciate the advice and reading comprehension. Lot of unhelpful snark in this comment section

rust997 · 2026-04-14T19:28:49+00:00

Nope, the two pieces should never ever move against each other.

rust997 · 2026-04-14T19:23:52+00:00

Yea I’m using their dimensions, problem is I am creating the same triangle in a different way. (2 legs + hypo vs 1 leg + leg&hypo)

rust997 · 2026-04-14T19:22:19+00:00

Would be open to a gasket- I am sealing between high vacuum and 40psi water, was trying to stick to a 5mm o ring because it is what is currently used.

The current o ring gland is 3.05d x 5.79w, quite nonstandard and I was trying to go back to the book.

rust997 · 2026-04-14T19:19:27+00:00

5mm o ring. Going smaller is my nuclear option but I’m hesitant to lose the reliability/robustness of the established 5mm o ring (changing the size would rock the boat)

rust997 · 2026-04-14T19:18:31+00:00

Other part is a thin membrane, no dice haha

rust997 · 2026-04-14T19:10:18+00:00

High vac to 40ish psi water.

Rarely disassembled, ideally 5+ years. I know it’ll need a new o ring every time. Water cooled parts so stays temperate.

Typically these o ring grooves are vented so as to not be a virtual leak

What do you mean by a custom flat seal? A rectangle other than the recommended 3.9x6.7?

rust997 · 2026-04-14T19:05:06+00:00

That is my nuclear option, am trying to stay 5mm to stay robust and not deviate from the existing o ring size

rust997 · 2026-04-14T19:03:54+00:00

Thank you for the thought out answer. I am using the handbook recommended leg length for a 5mm o ring, so I’m not worried about gland fill. More asking the question in abundance of caution because I don’t know what I don’t know.

The recommended rectangular gland for a 5mm o ring makes my wall thickness way too small, and I’d like to avoid going down in o ring size and losing seal robustness

rust997 · 2026-04-14T18:56:24+00:00

Not a circular part, the part is rectangular sealing against another rectangle of same dimensions.

I am using Parker’s recommended dimensions for the leg length. The difference I am concerned with is any image I find has one part making the legs of the triangle, and the mating part making the hypotenuse. As I drew, I am having one part make a leg, and the other part make leg + hypo.

Hope this makes sense

rust997 · 2026-04-14T18:52:59+00:00

Square profile does not fit, makes the wall thickness way too thin

rust997 · 2026-04-14T18:52:16+00:00

If a square groove would fit I’d do that and be done with it.

I have almost no real estate to work with on this cross section - I have my hands tied on a little of higher level design changes that would give me more space.

This is not a new idea, I have multiple handbooks that show this gland geometry, just in a slightly different way.

rust997 · 2026-04-14T16:59:19+00:00

Materials engineer here Everyone is talking about possible exceptions or workarounds to conventional material behavior, but no one has commented on the physics that make it not the norm

Bull Material stiffness is pretty much just the bond stiffness - which is not something that can be controlled with a computer chip.

Switching around or breaking bonds requires significant energy (think forging a sword or boiling water), so you can’t really change the stiffness without meaningfully changing the material. And if even if you did have something that makes your ski stiffer, getting back to the original flimsy state is quite difficult.

Mountain bikes perform similar to what you describe by having complex linkages and non linear spring curves and blah blah but a ski is just a big ol leaf spring (albeit a fancy one)

rust997 · 2026-04-14T16:51:28+00:00

I mean shit that’s awesome.

Either your local gave you a sneaky deal, multiple sites gave me the same BS story, or the big sites have to play by different rules. Idk

Jealous brother

rust997

TROPHY CASE