# Making o ring tool for lathe



## FTlatheworks (Aug 31, 2021)

Anyone know how to make o-ring grooving tool?


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## Nutfarmer (Aug 31, 2021)

I would grind one out of a high speed steel blank tool bit. Just make sure to to have some front and side clearance. With a little care and time one should be able to grind it by hand while checking the width frequently to hit size


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## benmychree (Aug 31, 2021)

Look in machinery's handbook for specs.  They are not straight sided, but slightly angled and with a nose corner radius and are wider than the actual O ring width.


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## Jimsehr (Aug 31, 2021)

I have hand ground many o ring groove tools. And the grooves I made were all straight sided. I have done thousands of parts with them. Also done o ring face groove tools.  I have many special groove micrometers and depth gages to check them. And also have gages to check dia of grooves. 
Jimsehr


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## RJSakowski (Aug 31, 2021)

Ideally, an O ring groove has a cross sectional area slightly less than the cross sectional area of the O ring.  The amount of the difference depends upon whether the design is for a static or dynamic seal and runs around 10 - 15 %.  O rings are incompressible but deformable so the actual geometry of the gland is less important than the actual volume of the gland.  The actual dimensions of the standard O rings are given in McMaster Carr's catalog as well as those of manufacturers.

I have ground my own tools out of HSS.  I generally grind a straight walled cutter with a width to match the design width of the groove.  Internal grooves require some special attention as to depth as it is difficult to accurately measure depth without special tools.


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## benmychree (Aug 31, 2021)

I would encourage others to "look at the book" so far as O ring groove specs; I still have a spec sheet form Kaiser Steel of O ring groove specs, and they are not straight sided and are wider than the O ring itself.  We made our own hydraulic cylinders and other hydraulic appauratus there, I still have a drawing of their hydraulic cylinder standards that they used, of the Ortman- Miller design.


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## Illinoyance (Aug 31, 2021)

+ 1 on going to the book, specifically the Parker O ring book, available on line.


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## Jimsehr (Sep 1, 2021)




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## FTlatheworks (Sep 1, 2021)

I have seen the Parker o ring book, but don’t understand it. I am in calculus 2 right now, but I still find it hard to understand the machinist handbook o ring tables. I am making a pressure to force gauge, so I believe it is a static seal. I have tested it with a buna n  O ring and I got 8,000 psi with a 1/2 inch with a 1/2 inch press ram. The bore is 1 square inch, so I get 1 psi per lb of force on the gauge. I used a parting blade to make the groove. The whole unit is made out of aluminum. This was for prototyping, but I’m not sure it will hold up for very long. The tolerances are not great and the finish is poor compared to what a professionally manufactured hydraulic cylinder would be. If I was far enough in my engineering degree I probably wouldn’t need to ask if aluminum is ok to be making this unit out of, but it was the cheapest option for prototyping. I wish my skills were high enough to do the math to see if the metal could handle the pressures and all the other calculations needed to make the right part the first time out of the right materials.

Does anyone have a diagram of the degrees the tool should be? I will look in the machinist handbook tomorrow for the rest in between work and class.


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## FTlatheworks (Sep 1, 2021)

Jimsehr said:


> I have hand ground many o ring groove tools. And the grooves I made were all straight sided. I have done thousands of parts with them. Also done o ring face groove tools.  I have many special groove micrometers and depth gages to check them. And also have gages to check dia of grooves.
> Jimsehr


Sounds pricey.


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## FTlatheworks (Sep 1, 2021)

Nutfarmer said:


> I would grind one out of a high speed steel blank tool bit. Just make sure to to have some front and side clearance. With a little care and time one should be able to grind it by hand while checking the width frequently to hit size


I have some 5/8 hss and 3/8 hss blanks I can use up.


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## Jimsehr (Sep 1, 2021)

FTlatheworks said:


> Sounds pricey.


It is and was. I have a micrometer that just checks groove width. I have some special depth mic rods to check groove width and location. And have some gages to check id groove diameters. And I have some blade mics to fit into od grooves to check dia.
Jim Sehr
 In production I have run tens of thousands of o ring grooves.


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## Jimsehr (Sep 1, 2021)

Groove sides.


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## Jimsehr (Sep 1, 2021)

FTlatheworks said:


> I have some 5/8 hss and 3/8 hss blanks I can use up.


What size is the groove. Is it od or Id ?
3/8 tool bit should work fine. Need to grind radius at bottom of tool.
I have cut grooves wider by moving tool sideways if you grind it too narrow.
Jim Sehr 
also what lathe do you have?


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## FTlatheworks (Sep 1, 2021)

Jimsehr said:


> What size is the groove. Is it od or Id ?
> 3/8 tool bit should work fine. Need to grind radius at bottom of tool.
> I have cut grooves wider by moving tool sideways if you grind it too narrow.
> Jim Sehr
> also what lathe do you have?


I have a pm1236. The o rings are 1 inch id and 1 1/8 inch od and I have 1/16 inch thick and 1/8 inch thick rings. I also have back up rings because it needs to be able to measure up to 10,000 psi with a 1 inch rammer, piston, and bore.


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## FTlatheworks (Sep 1, 2021)

FTlatheworks said:


> I have a pm1236. The o rings are 1 inch id and 1 1/8 inch od and I have 1/16 inch thick and 1/8 inch thick rings. I also have back up rings because it needs to be able to measure up to 10,000 psi with a 1 inch rammer, piston, and bore.


I don’t like using my parting tool because they don’t sharpen well after they get dull, so they flex and cause an oblong groove. It doesn’t matter how much time I spend honing and cleaning the parting blade and how close into the holder I get. The holder I have also can’t hold blades straight as they should be. The top of the blade is thicker so no matter what when it is tightened down it is at a small angle, so it draws, or grabs one side more than the other.

where is the info about how to grind specific lathe tools in the machinist handbook. I have looked through the he tooling section and find no mention of angles, or methods to grind specific tools. I don’t think I understand how to fully utilize this book yet.


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## Janderso (Sep 1, 2021)

benmychree said:


> I would encourage others to "look at the book" so far as O ring groove specs; I still have a spec sheet form Kaiser Steel of O ring groove specs, and they are not straight sided and are wider than the O ring itself.  We made our own hydraulic cylinders and other hydraulic appauratus there, I still have a drawing of their hydraulic cylinder standards that they used, of the Ortman- Miller design.


I was flipping pages last week, I saw the section on Orings. That book has everything and then some.


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## Jimsehr (Sep 1, 2021)

I used to make stuff for a company that made O rings. And I became a fan of quad rings. It is like putting 2 rings in 1 groove.


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## Jimsehr (Sep 1, 2021)




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## macd55 (Sep 1, 2021)

Note the sides of an o ring grove is 0 degrees to +5 degrees hence the easiest  way to get the required 62 finish on the sides is to grind a tool undersize on the width and face the sides after you plunge the required depth. I worked in aircraft machine shops making parts for Boeing for 45 years and we always machined them that way.


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## Jimsehr (Sep 1, 2021)

FTlatheworks said:


> I don’t like using my parting tool because they don’t sharpen well after they get dull, so they flex and cause an oblong groove. It doesn’t matter how much time I spend honing and cleaning the parting blade and how close into the holder I get. The holder I have also can’t hold blades straight as they should be. The top of the blade is thicker so no matter what when it is tightened down it is at a small angle, so it draws, or grabs one side more than the other.
> 
> where is the info about how to grind specific lathe tools in the machinist handbook. I have looked through the he tooling section and find no mention of angles, or methods to grind specific tools. I don’t think I understand how to fully utilize this book yet.


I think you should look up the Benefits of using a quad ring In place of a O ring.
If I recall it right an O ring twists and the rubber moves more and breaks down guicker than a quad ring. 
As far as grinding tools go I am so old school I just learned by trial and error. I have never believed that the angles were that important. My hand ground tools seem to work for me and I never have checked the angles on them.
In fact I made a ball turner tool that has a cutting tool with zero clearance. I was told it would not work. But it works fine for me. True it will not face but does what I made it for. 
Jim Sehr


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## Jimsehr (Sep 1, 2021)

Here are some tools I have that are for checking O ring grooves.


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## FTlatheworks (Sep 1, 2021)

Jimsehr said:


> Here are some tools I have that are for checking O ring grooves.


Never seen tools like that. That’s pretty cool.


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## Mitch Alsup (Sep 1, 2021)

The cross section of the O-ring is essentially round, and thus has an area of pi×d.
The cross section of the hole an o-ring sits in is narrower than the o-ring and shallower, creating a 30% squish.
Notice that 4/pi = 1.2732..... or 27%
The 30% squish means there is 30%-27% = 3% of the o-ring that does not fit in the grove. This part of the o-ring will fit into the ID versus OD tolerance, fit into surface finish, and is preventing the gas or liquid from entering or leaving.


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## hman (Sep 1, 2021)

OK, this ain't "making" a tool.  But you can buy a wide variety of grooving tools from Thinbit:





						Groove 'N Turn®
					

Groove 'N Turn® by Kaiser Tool Company, Inc. THINBIT®




					www.thinbit.com
				




Kudos to @macardoso, who just posted about these - post #11 at 








						O-ring groove tool: Make or buy?
					

Just throwing this out there. If you have a part with dimensions requiring accuracy (customer part) for the groove, Thinbit by kaiser makes inserts with the proper geometry for both static and dynamic o-ring seals. Run about $15 for the insert I believe...




					www.hobby-machinist.com


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## FTlatheworks (Sep 1, 2021)

Mitch Alsup said:


> The cross section of the O-ring is essentially round, and thus has an area of pi×d.
> The cross section of the hole an o-ring sits in is narrower than the o-ring and shallower, creating a 30% squish.
> Notice that 4/pi = 1.2732..... or 27%
> The 30% squish means there is 30%-27% = 3% of the o-ring that does not fit in the grove. This part of the o-ring will fit into the ID versus OD tolerance, fit into surface finish, and is preventing the gas or liquid from entering or leaving.


Very nice explanation, Thank you.


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## Ischgl99 (Sep 1, 2021)

FTlatheworks said:


> I don’t like using my parting tool because they don’t sharpen well after they get dull, so they flex and cause an oblong groove. It doesn’t matter how much time I spend honing and cleaning the parting blade and how close into the holder I get. The holder I have also can’t hold blades straight as they should be. The top of the blade is thicker so no matter what when it is tightened down it is at a small angle, so it draws, or grabs one side more than the other.
> 
> where is the info about how to grind specific lathe tools in the machinist handbook. I have looked through the he tooling section and find no mention of angles, or methods to grind specific tools. I don’t think I understand how to fully utilize this book yet.


Sounds like you have the standard blade that came with the holder.  Give a P type blade a try, works much better.


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## Jimsehr (Sep 2, 2021)

And there also different types of O rings for special needs.

View attachment 377018



FTlatheworks said:


> Never seen tools like that. That’s pretty cool.


I think that the groove micrometer sells for between $250 and $350 dollars now. And the tool for checking dia is probably more than that. But the one in pic is one
I made over 60 years ago. And the rods used in depth mics are probably about $75 dollars each and I have about 4 or five of them made to fit different brands of depth mics.
Jim Sehr


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## FTlatheworks (Sep 2, 2021)

Ischgl99 said:


> Sounds like you have the standard blade that came with the holder.  Give a P type blade a try, works much better.


I will, thanks! I relied on a store front to sell me the best option for a parting blade. I have done a lot of parting with it successfully, but I know it could be a lot better.


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## FTlatheworks (Sep 2, 2021)

Jimsehr said:


> And there also different types of O rings for special needs.
> 
> View attachment 377018
> 
> ...


That’s awesome! I can’t believe how much tooling is for these machines. I understand why most of the time, but still, it’s a fortune just for a very small variety of tooling.


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## Jimsehr (Sep 2, 2021)

FTlatheworks 
Did you check out the properties of the Quad rings?
Jim Sehr


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## Ischgl99 (Sep 2, 2021)

FTlatheworks said:


> I will, thanks! I relied on a store front to sell me the best option for a parting blade. I have done a lot of parting with it successfully, but I know it could be a lot better.


I had a problem with my parting blade tilting like you, but once I switched to a P type, it was much better.  Since the blade is shaped like a T, you might need to cut a small groove for the top of the blade so that it fits flush with your toolholder.  I think I just used a file on mine.


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## FTlatheworks (Sep 3, 2021)

Jimsehr said:


> FTlatheworks
> Did you check out the properties of the Quad rings?
> Jim Sehr


Not yet, I will tonight. I won’t be able to order anything, so I’m working with what i got and talking about it on here.


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## Jimsehr (Oct 12, 2021)

FTlatheworks said:


> Not yet, I will tonight. I won’t be able to order anything, so I’m working with what i got and talking about it on here.


Here is pic of bigger view of sides of o ring. Showing angle of side option.


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## k2steve (Oct 12, 2021)

Jimsehr said:


> View attachment 376949


Nice Chart,  Thank you


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