Making o ring tool for lathe

[Jimsehr]

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

 

[Jimsehr]

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

 

[FTlatheworks]

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

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

 

[Mitch Alsup]

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.

 

[hman]

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

 

[FTlatheworks]

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.

 

[Ischgl99]

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.

 

[Jimsehr]

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

View attachment 377018

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

 

[FTlatheworks]

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.

 

[FTlatheworks]

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

View attachment 377018

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

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.