Looking for a big o-ring

Billy Boy · Sep 17, 2007

I'm putting together an order for a new full set of viton o-rings for my vacuum chamber restoration project. I've got all the o-ring dash numbers except one. This o-ring has a 3/8" diameter cross section and a 24 1/8" ID!! Not an o-ring with a dash number as far as I can tell.

Is there a source for a large o-ring like this, or do I have to fab it out of cord stock ( which is available through normal channels).

If I do need to fab this, what sort of glue should I use?

Thanks,

B

toolmakerjim · Sep 17, 2007

get ahold of Morton~Thikhol i think they have a bunch of left over solid rocket booster O-Rings for the space shuttle...jim

George Hodge · Sep 17, 2007

That sounds just like the sealing 'O'ring on an off road loader or grader tire.They are used to seal the bead on some rims.Should be very close to the same size.Heavy equipment tire shops have them.

Jon Bohlander · Sep 17, 2007

You could try one of these splicing kits I've used them before to make a seal for a homebrew vacuum chamber door at work.

Edit: I just saw the 3/8" part. Here's the
cordstock
All the kit has is a razor blade, super glue, a jig to help cut square and glue the cord straight

surplusjohn · Sep 17, 2007

loctite used to sell a kit with the adhesive and o ring stock and a slpicing jig

JST · Sep 17, 2007

LOL
TMJ..... you have the same type evil mind I do..... I had that same thought when I saw the thread title......

toolmakerjim · Sep 17, 2007

i resemble that statement...jim

RDL · Sep 18, 2007

Splicing kits are a solution. I have also used Devcon to make my own Freeze Drier Seals. I believe that Devcon has more hardness choices.

Raymond

jims · Sep 18, 2007

Try National o-rings
Downey ca
800 421-3837

Jim

Fasto · Sep 18, 2007

I have used Quick Cut Gasket for all sorts of custom O-rings, square section O-rings, quad seal O-rings...
Quick Cut Gasket Or 1-877-606-5778.

You'd be surprised at how little a custom O-ring or square section gasket costs.
--
Aaron

Butcher · Sep 18, 2007

Try
A. C. DePUYDT
5843 Sheila St.
Los Angeles Ca. 90040
(323) 721-4800
(323) 721-4892 Fax.

Billy Boy · Sep 18, 2007

Thanks guys,

Called all those guys and a couple others... except National as their phone doesn't seem to be working.

Seems that my o ring is a custom part for all these guys. So, it is going to be a 4-8 week lead time and is not going to cost any less than if I buy the cord stock and glue and fab it myself.

So, my plan is to by some cord stock, bore out a tube to .3750. Make a little jig to cut the stock straight, cut with a sharp razor, glue together, and clamp the ends together in that .3750 tube.

Seems like there may be a bit of an inconsistency at the seam, so I guess I will put a thin film of vacuum grease at that point to plug up any potential leaks.

Does this sound like a plan? Any suggestions?

B

toolmakerjim · Sep 18, 2007

i would cut the material on the bias rather than straight. you'll have more surface area to glue and the vacuum will be spread over a larger area...jim

Charles Dolan · Sep 18, 2007

I make all sorts of 'O' ring all the time and I am afraid that depending on how high a vacuum you wish to pull you may be SOL with a home fabricated ring. The joint in thr ring
invariably has some misalignment in it and because of the very low pressure diference of 1 bar there is insufficient mechanical force to seal. Try to buy one made up, but if you must make it use Loctite super- glue.

Charles

MetalMelter · Sep 18, 2007

You might try contacting Varian or Veeco. They deal with high vac equipment on a big scale and may be able to help you. Is it going into something like this? That's an 18" ID jar. If your using a split ring on a high vacuum application your probably headed for problems holding a proper vacuum. There should be plenty of places that make viton o-rings to custom size. You might pay a bit more but definitely worth every penny.

I'll see if I can locate a source for ya.

Billy Boy · Sep 18, 2007

Diverse,

Yep. That's the ticket. Your's has got a lot more fancy dials on it than mine. Mine is an old sputter chamber that I'm rigging up other purposes.

Hmmm... I'm hoping to be hitting 10^-6 torr with this rig.

The guys who fab them must have some way to make them line up right.

B

macona · Sep 18, 2007

Make sure you get Viton, not Buna-N

eKretz · Sep 19, 2007

BillyBoy, they do...they make them one piece. And I would cut the o-ring straight if your going to cut it. If you cut it on an angle, you will NEVER get it lined up right. With o-rings and super glue you don't have to worry about the surface area, once they're stuck, they're NOT coming apart at the glue joint. Whether it will hold at that kind of vacuum level I don't know. I think someone makes an o-ring splicer that vulcanizes the joint...I think I saw it in the McMaster-Carr catalog. However, if you don't make a lot of o-rings and only need the one...you'd be better off just having it made...the thing is close to a grand if I remember correctly.

MetalMelter · Sep 19, 2007

BillyBoy,

The real problem your facing with using any glue to splice an o-ring is outgasing of the glue during vacuum which can prevent you from getting to the level of vacuum your after. Plus if your sputtering you may end up with trapped gases below the layer of sputtered material. Try and stay away from a cut o-ring as much as possible. You will find the size you need. Just keep looking in google. Viton o-rings appear to be the best bang for your money.

So.... making a fusor chamber are we?

LOL

That machine in the picture I saved from the scrap man along with a helium leak detector and a bunch of other precision equipment. It was the holy grail for me that day. The deposition unit is a dual 500 amp model. The pump is a tad tired but aside from that I re-wired the unit almost completely and boy does it make a tungsten element glow

I got some cool pictures on my site. Take a look if your into it: http://www.glowhound.com/sales/equipmentsales/page2/index.html

MarkL · Sep 19, 2007

I everyone...Apple Rubber products in Lancaster NY manufactures any size o-ring possible and in any rubber formula. Use them all the time. Check them out. They sell in small quantities also. Mark in Buffalo

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