Deciding Size of Oring

Titan · 12-27-2003, 04:40 AM

Need a little help on how to choose an Oring. For example this groove here should the diameter of the oring be the Length X or Y. Or should the longer length be taken if any other shapes were to be used for example a rectangle.

Teus · 12-27-2003, 05:13 AM

I think (X+Y)/2

Dieter@be · 12-28-2003, 03:52 PM

ellips:
(x^2/a^2)^2 + (y^2/b^2)^2 = 1

an ellips doesnt have "a" diameter.
it does have a "long diameter" and a short one, which are 2a and 2b (on your drawing x and y)

i dont understand your 2nd question.

btw:
http://forums.procooling.com/vbb/att...=&postid=97151
this pic i found in the sticky

Titan · 12-31-2003, 01:47 AM

Hmmm... I think i should rephrase my question again......here we go....
How should i select O rings for irregular shapes such as an eclipse. Should i take the "Diameter" or the Length of the longer side or the shorter one. Hope my question is clear enough. Pardon my english, I know it suxs

Teus · 12-31-2003, 03:34 AM

a regular O-ring will do, you can stretch them. the D-Tek WW that I've fixed also had a circular O-ring. it fitted perfectly in the milled grooves of the block

Gooserider · 01-02-2004, 09:48 PM

I am not an expert on O-rings, so you will need to double check this - I am certainly open to corrections.

There are two numbers in the size of an O-ring, one is the diameter of the rubber the ring is made out of, and that is a function of the groove dimension. (if designing a block, there is a spec for groove size in the hole spacing sticky in the design forum.) The second number is the diameter of the circle formed by the ring itself. I believe it's the average between the OD and ID, but I could be wrong.

If the O-ring groove isn't circular, then one needs to find the length of the groove, (either by measurement or calculation) then calculate the equivalent diameter of a circle with the same length, then get an O-ring with the same or slightly smaller diameter.
(ie if length = 3.14" then get a 1" diameter O-ring) O-rings can easily be shaped to fit into irregular grooves. They can be stretched SLIGHTLY to do this, but don't like being squished into a shorter length.

If designing a block, it is necessary to design the groove so that it has a length that is the same as an available part. While it is possible to custom make O-rings in any size, this is generally considered a less than optimal approach.

(BTW, if I needed to find the size of an unknown irregular shaped O-ring, groove, I would probably do it by getting a peice of non-stretchy string approx the right diameter and wrapping it into the groove, cutting it to the right length and measuring the result. This would probably be easier, faster and more acurate than any calculation)

Gooserider

jaydee · 01-03-2004, 10:56 AM

You can also get some O-ring material and make your own O-ring to fit. That's what I do. Use super glue to connect the ends. If you are thinking about doing this commercially and can't find a pre-made one to fit then you can custom order them to any size you need but they will have to be in quantity.

Also if your using a CAD program click on the O-ring groove and select properties and it should (I think)tell you how long it is. There is other ways in ACAD2000 but I can't remember them off the top of my head.

siavash_s_s · 01-03-2004, 07:43 PM

this is a bit further off from o rings, but u may want to try a gasket? no milling involved atleast

12-28-2003, 03:52 PM	#3
Dieter@be Cooling Neophyte Join Date: Nov 2003 Location: Belgium\Wetteren Posts: 94	ellips: (x^2/a^2)^2 + (y^2/b^2)^2 = 1 an ellips doesnt have "a" diameter. it does have a "long diameter" and a short one, which are 2a and 2b (on your drawing x and y) i dont understand your 2nd question. btw: http://forums.procooling.com/vbb/att...=&postid=97151 this pic i found in the sticky Last edited by Dieter@be; 12-28-2003 at 03:59 PM.

01-02-2004, 09:48 PM	#6
Gooserider Cooling Savant Join Date: Jun 2003 Location: North Billerica, MA, USA Posts: 451	I am not an expert on O-rings, so you will need to double check this - I am certainly open to corrections. There are two numbers in the size of an O-ring, one is the diameter of the rubber the ring is made out of, and that is a function of the groove dimension. (if designing a block, there is a spec for groove size in the hole spacing sticky in the design forum.) The second number is the diameter of the circle formed by the ring itself. I believe it's the average between the OD and ID, but I could be wrong. If the O-ring groove isn't circular, then one needs to find the length of the groove, (either by measurement or calculation) then calculate the equivalent diameter of a circle with the same length, then get an O-ring with the same or slightly smaller diameter. (ie if length = 3.14" then get a 1" diameter O-ring) O-rings can easily be shaped to fit into irregular grooves. They can be stretched SLIGHTLY to do this, but don't like being squished into a shorter length. If designing a block, it is necessary to design the groove so that it has a length that is the same as an available part. While it is possible to custom make O-rings in any size, this is generally considered a less than optimal approach. (BTW, if I needed to find the size of an unknown irregular shaped O-ring, groove, I would probably do it by getting a peice of non-stretchy string approx the right diameter and wrapping it into the groove, cutting it to the right length and measuring the result. This would probably be easier, faster and more acurate than any calculation) Gooserider __________________ Designing system, will have Tyan S2468UGN Dual Athlon MOBO, SCSI HDDS, other goodies. Will run LINUX only. Want to have silent running, minimal fans, and water cooled. Probably not OC'c

01-03-2004, 07:43 PM	#8
siavash_s_s Cooling Savant Join Date: Aug 2003 Location: here n there Posts: 194	this is a bit further off from o rings, but u may want to try a gasket? no milling involved atleast __________________ buy me a mill

12-27-2003, 05:13 AM	#2
Teus Cooling Neophyte Join Date: Jun 2003 Location: Belgium\Ieper Posts: 65	I think (X+Y)/2

12-31-2003, 01:47 AM	#4
Titan Cooling Neophyte Join Date: Sep 2003 Location: CPU world Posts: 15	Hmmm... I think i should rephrase my question again......here we go.... How should i select O rings for irregular shapes such as an eclipse. Should i take the "Diameter" or the Length of the longer side or the shorter one. Hope my question is clear enough. Pardon my english, I know it suxs

12-31-2003, 03:34 AM	#5
Teus Cooling Neophyte Join Date: Jun 2003 Location: Belgium\Ieper Posts: 65	a regular O-ring will do, you can stretch them. the D-Tek WW that I've fixed also had a circular O-ring. it fitted perfectly in the milled grooves of the block

01-03-2004, 10:56 AM	#7
jaydee Put up or Shut Up Join Date: Dec 2001 Location: Spokane WA Posts: 6,506	You can also get some O-ring material and make your own O-ring to fit. That's what I do. Use super glue to connect the ends. If you are thinking about doing this commercially and can't find a pre-made one to fit then you can custom order them to any size you need but they will have to be in quantity. Also if your using a CAD program click on the O-ring groove and select properties and it should (I think)tell you how long it is. There is other ways in ACAD2000 but I can't remember them off the top of my head.

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