O Ring Kits

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O Ring Kits

This topic has 13 replies, 8 voices, and was last updated 24 January 2023 at 16:41 by Vic.

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17 January 2023 at 18:48 #629887
Vic
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@vic
I’ve needed a number of different O Rings recently and without exception they’ve all had a 2mm C/S. I’ve got a couple of small boxes of mixed sizes and they’re all 1.5mm, 2.5mm or larger C/S! I have looked at other kits on the market and they all seem to omit 2mm. I’ve ordered what I need now from a supplier on the auction site and just in case I’ve ordered a few other sizes in the same C/S. anyone else come across this anomaly?!
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17 January 2023 at 18:48 #37115
Vic
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@vic
17 January 2023 at 18:59 #629890
Baz
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@baz89810
Yeah had the same problem myself late last year, thank goodness for eBay. I managed to get all I needed plus pares plus a few extra sizes just in case.
17 January 2023 at 19:41 #629896
noel shelley
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@noelshelley55608
For what the kits cost (£ 12) I bought both imperial and metric, gives me a huge choice of sizes and section. Then a few yards of various size cord and a pot of superglue and you can make your own. Noel.
21 January 2023 at 16:14 #630488
Vic
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@vic
I needed another size, once more not in any kits that I’ve seen – 12mm OD x 1.5 CS. Do the people that make up these kits do it on purpose?!
I’m so glad I didn’t lay out ten or fifteen quid for one of these kits as they never seem to have the size I need.
21 January 2023 at 17:12 #630500
Ian P
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@ianp
Posted by Vic on 21/01/2023 16:14:02:

I needed another size, once more not in any kits that I’ve seen – 12mm OD x 1.5 CS. Do the people that make up these kits do it on purpose?!
I’m so glad I didn’t lay out ten or fifteen quid for one of these kits as they never seem to have the size I need.

I use a fair number of O-rings is stuff that I design and make yet very rarely use an O-ring out of either the metric and imperial kits I have. Two reasons really, one is the seal material which is a bit of an unknown quality, secondly is whilst a kits look to cover a range of sizes, in reality its is a fraction of the standard size range.

I sometimes need to seal 1.5mm (and sometimes smaller) control spindles, and up to 250mm diameter bayonet joints so well outside what kits contain. For underwater use my preference is silicone rubber.

Ian P
21 January 2023 at 17:31 #630502
Oldiron
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@oldiron
Posted by Vic on 21/01/2023 16:14:02:

I needed another size, once more not in any kits that I’ve seen – 12mm OD x 1.5 CS. Do the people that make up these kits do it on purpose?!
I’m so glad I didn’t lay out ten or fifteen quid for one of these kits as they never seem to have the size I need.

In case anyone does not know. O rings are sized by Inside diameter and cross section. ie 18 x 3's are 24mm OD withh 3mm cross section. If you order 18mm x 3mm O ring what you actually get is an 24mm OD x 3mm CS. So when ordering make sure you order correctly.

regards
23 January 2023 at 07:17 #630667
michael howarth 1
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@michaelhowarth1
Not wishing to teach anyone to suck eggs, Imperial "O" rings are sized by ID x OD as opposed to the metric sizing above.

Mick
23 January 2023 at 09:39 #630671
noel shelley
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@noelshelley55608
Then there are several different materials, nitrile, Viton, silicone, Etc and a hardness – The shore number. 70 is normal. Noel
23 January 2023 at 10:57 #630686
Vic
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@vic
The Metric ones I’ve been getting from a specialist on eBay are clearly marked ID x CS. I think they even have a diagram for the hard of understanding!
23 January 2023 at 11:11 #630692
Ian P
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@ianp
Posted by mick H on 23/01/2023 07:17:44:

Not wishing to teach anyone to suck eggs, Imperial "O" rings are sized by ID x OD as opposed to the metric sizing above.

Mick

For the sake of clarity and avoidance of confusion

O-rings whether metric or imperial are referred to by the inside diameter followed by cross section

Ian P
23 January 2023 at 17:16 #630737
Georgineer
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@georgineer
Posted by mick H on 23/01/2023 07:17:44:

Not wishing to teach anyone to suck eggs,

Ah yes:

"Teach not thy parent's mother to extract /The embryonic juices of an egg by suction./That worthy lady can herself enact,/Quite irrespective of thy kind instruction." Boy's Own Paper, April 29, 1882.

The problem I have found with O-ring kits (along with other kits in compartmented plastic trays) is that they seldom list the dimensions of the parts in the compartments.

George
24 January 2023 at 12:55 #630835
Martin Johnson 1
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@martinjohnson1
I also have one of those O ring boxes, and it only rarely has the required item. Add in extra complication of material specs such as viton for higher temperatures then its a no brainer. Auction site all the way.

Martin
24 January 2023 at 16:41 #630852
Vic
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@vic
Obviously not as cheap as buying a plastic box of assorted sizes at Lidl but the prices I’ve seen so far on eBay don’t seem too bad. Strangely though I only seem to see one vendor on there. Perhaps my search term isn’t wide enough?! Service from them so far has been pretty good.
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