# O-ring placeholders... Figuring out
**URL:** https://foil.zone/t/o-ring-placeholders-figuring-out/1826
**Category:** Props & Ducts
**Created:** [May 28, 2018, 6:56am UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826 "2018-05-28T06:56:27Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@philgib](https://foil.zone/u/philgib)
#### Post date: [May 28, 2018, 6:56am UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826/1 "2018-05-28T06:56:27Z")
Hello guys,
Any o’ring specialist here ?
- is it better to choose an o’ring slightly smaller than the space where it would sit into, so that it spreads a bit when being installed ? Or should it be the exact same diameter as the channel width ?
- what width for the channel it sits into compare to the thickness of the o’ring, knowing that it will squeeze even more when you press-fit the tube ?
- how deep should the channel be ? 1/3 of the o’ring thickness ? 1/2 ?
- should the channel shape profile be a square or rectangle ?
- what o’ring shape would do you prefer ? Round, cut square, quad ?
Thank you
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### Author:  [@pacificmeister](https://foil.zone/u/pacificmeister)
#### Post date: [May 28, 2018, 7:04am UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826/2 "2018-05-28T07:04:00Z")
There is quite some science behind Orings. The Parker Oring handbook helped me a lot: [https://www.parker.com/literature/ORD%205700%20Parker\_O-Ring\_Handbook.pdf](https://www.parker.com/literature/ORD%205700%20Parker_O-Ring_Handbook.pdf)
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### Author:  [@MaxMaker](https://foil.zone/u/MaxMaker)
#### Post date: [May 28, 2018, 7:10am UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826/3 "2018-05-28T07:10:42Z")
O-rings are a thing that engineers don’t know by heart. You typically let o-ring manufacturers advise you on that. They all have PDF guidebooks or even online calculators where you input your parameters.
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### Author:  [@Toto44](https://foil.zone/u/Toto44)
#### Post date: [May 28, 2018, 7:36am UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826/4 "2018-05-28T07:36:06Z")
maybe this helps you
> **[O-Ring Groove Design Guides | Engineering Quick Reference](https://www.marcorubber.com/o-ring-groove-design-directory.htm)**
>
> View basic o-ring design guides for grooves, glands, depth, width, clearance, stretch, squeeze and more from Marco Rubber O-Ring specialists and buy online
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### Author:  [@philgib](https://foil.zone/u/philgib)
#### Post date: [May 28, 2018, 11:57am UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826/6 "2018-05-28T11:57:48Z")
Found this excellent guide explaining with basic words what to look for :
> **[Nothing Gets In: Waterproof Enclosure Design 101 (and IP68) - Fictiv](https://www.fictiv.com/articles/nothing-gets-in-waterproof-enclosure-design-101-and-ip68)**
>
> Read more about the design guidelines for waterproof enclosure design, as well as IP68 waterproof rating design.
I did not realize that there should be some angle (alpha on the below graph) along the groove depth. It does make sense.
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### Author:  [@NLS](https://foil.zone/u/NLS)
#### Post date: [June 2, 2018, 6:53pm UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826/7 "2018-06-02T18:53:30Z")
Its true you should have some angle and radii in the corners and probably the most important factor is the extrusion gap. However, keep in mind that o-rings are capable of sealing pressures up to 5,000psi. So in this application its ok to cut corners and simplify things. The parker o-ring handbook is a great resource.
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### Author:  [@g.gregory8](https://foil.zone/u/g.gregory8)
#### Post date: [January 2, 2019, 11:52pm UTC](https://foil.zone/t/o-ring-placeholders-figuring-out/1826/8 "2019-01-02T23:52:21Z")
Nice article, I wasn’t aware of the alpha angle either. I don’t believe I saw this in the parker handbook so my grooves are square.
That article doesn’t appear to mention how to calculate the parameters on the screenshot. Is this information elsewhere?