How To Turn A Round Groove?

Not rare at all, do a Google search for lathe profile tooling, Manchester springs to mind for large tools and Kaiser thin bit for smaller parts, Kennametal has an excellent selection of form grooving tools. http://www.kennametal.com/en/featured/grooving.html

If you are making parts that will not be measured by the customers inspection department then improvise.

By all means grind your own tooling from HSS or carbide blanks.
 
When I cut o ring grooves, I cut the groove then round the bottom with a round file of the right size. Works OK, and saves me the trouble of grinding radii every time. Be careful not to widen the groove too much, it can happen if you're not careful.

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Andre, ring grooves designed for seals should not be round bottom. They are designed to actually allow some elastic flow in the 'o' ring itself due to the pressure they see. They fill the designed profile and exert pressure against the seal surfaces in a very specific way. They cannot function as designed with a round bottom groove. The ideal groove actually has a 2-5° angle on the flanks, wider at the top, and depending on the overall size, maybe a 0.010-0.015 radius in the inside corner and a 0.005-0.010 edge break on the OD.

Have a look at Parker's seal design guidelines. There are several scenarios where the profile and specifics are discussed as to how and why they are specified the way they are.
 
a .063" radius is .125" dia. so if you don't have a radius gauge drill and ream a 125" hole in a piece of sheet metal and cut it in half. this makes you a .063 radius gauge. then using a high speed steel parting tool grind the end to match your gauge. lots less grinding this way. turn the lathe to one of the slowest speeds you have and plunge cut the radius. lots of cutting fluid don't let it chatter by feeding to slow. practice on a scrap part until you like the results. the is also a round emery cloth to fix up the groove if necessary. hope this helps bill
 
Tony Wells said:
Andre, ring grooves designed for seals should not be round bottom. They are designed to actually allow some elastic flow in the 'o' ring itself due to the pressure they see. They fill the designed profile and exert pressure against the seal surfaces in a very specific way. They cannot function as designed with a round bottom groove. The ideal groove actually has a 2-5° angle on the flanks, wider at the top, and depending on the overall size, maybe a 0.010-0.015 radius in the inside corner and a 0.005-0.010 edge break on the OD.

Have a look at Parker's seal design guidelines. There are several scenarios where the profile and specifics are discussed as to how and why they are specified the way they are.
Click to expand...

Excellent advice O ring grooves should never be round bottomed, they have very specific dimensions and can be found in the Parker handbook.
 
I don't see any "O" ring groove in that pdf. Looks like a pulley type roller. A simple tool bit ground with the angle and radius would work just fine.
 
Tony Wells said:
Andre, ring grooves designed for seals should not be round bottom. They are designed to actually allow some elastic flow in the 'o' ring itself due to the pressure they see. They fill the designed profile and exert pressure against the seal surfaces in a very specific way. They cannot function as designed with a round bottom groove. The ideal groove actually has a 2-5° angle on the flanks, wider at the top, and depending on the overall size, maybe a 0.010-0.015 radius in the inside corner and a 0.005-0.010 edge break on the OD.

Have a look at Parker's seal design guidelines. There are several scenarios where the profile and specifics are discussed as to how and why they are specified the way they are.
Click to expand...
My mistake, I just used an O ring groove as an example.

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Well this project got passed by. I don't have any hand ground tooling, or a grinder setup to do it, and lastly I don't have the knowledge to actually grind my own tooling. This would be a handy skill to have. Clearly I can see the benefits and needs.

Is there any reason not to use carbide blanks and grind those?
 
dieselshadow said:
Well this project got passed by. I don't have any hand ground tooling, or a grinder setup to do it, and lastly I don't have the knowledge to actually grind my own tooling. This would be a handy skill to have. Clearly I can see the benefits and needs.

Is there any reason not to use carbide blanks and grind those?
Click to expand...

None at all except you will need special grinding wheels for the carbide. There are numerous books and many schools run courses on how to grind machuine toolss from drill it to complicated profile cutters.
 
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