External O-Ring Groove Lathe Tools?

Flyinfool said:
1 more for a cutoff blade. it will not matter if the bottom of the groove is square or round the o-ring is not trying to make a seal. If you want round bottoms just for the fun of it you could even grind the end of the cutoff blade to round.
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Fun fact, lots of O-ring grooves are square cornered and flat on the bottom.
 
MaverickNH said:
For my planned Machinist’s Hammer Hemingway Kit rendition, I’d like to put spaced O-Rings on the steel handle instead of Knurling it. Maybe a few more than pictured below.

My LMS 7x16 mini lathe takes 3/8” shank tool bits and has a 50-2500 RPM spindle speed range. What tools might be appropriate? I’d rather buy a few to start than try and grind my own.

I figure I can measure the diameter along the tapered handle and calculate which standard O-Ring might best fit at which position, at ~50% depth and a bit of stretch to keep the O-Ring snug (I think an O-Ring ID 5% under the workpiece OD is the standard).

BRET
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I would just take a HSS blank or even a previously used HSS and cut it with a small tip. I have a bunch of them. Most made by others that I got in lots. a couple I made to fit my needs. Since you only need a short nub to make the cuts it will be quick and easy.
 
Flyinfool said:
1 more for a cutoff blade. it will not matter if the bottom of the groove is square or round the o-ring is not trying to make a seal. If you want round bottoms just for the fun of it you could even grind the end of the cutoff blade to round.
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O-rings grooves for sealing purposes have square/flat bottoms.

I second going with A.R. Warner holders & bits: in addition to the grooving tool if you go that route, take a look at their #8 kit, then call them about taking out the boring bar if you have a different preference (they are great to work with):

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You may not have an immediate need for the LH turning tool, but the other end uses the sides of the insert for chamfering. The holders are high quality and the T-15 inserts are great - when they get dull or chipped, rub the top on a stone and you’re back in business.
 
It's just for looks so use whatever parting blade you have and buy the o rings to fit.
 
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eotrfish said:
NO

View attachment 468933

R varies from .005" to .035" depending on O-ring thickness.

Proper dimensions can be found in a Parker O-ring manual or online.
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0 - 5 degrees is close to 90, and the bottom is flat, but my point was that the slot wouldn’t have a round bottom.

I would have referenced the Parker manual and included a link if I wasn’t using my phone. The groove profile also varies depending on how the O-ring is sealing: axially, radially, ID pressure/OD pressure, etc.
 
I've been watching this thread for a few days and thought it was time to add another opinion. Maybe I'm just old and out of touch, but somehow, I can't follow the logic of spending $140.00 to over $200.00 to cut a few grooves in a $20.00 tool. I know the OP said he'd rather buy inserts than grind a tool, but in this case, I think the effort would be well worth it. In less than 15 minutes and $10.00 in tooling you could grind what you need from an HSS tool blank.

I've done it hundreds if not thousands of times. I currently have a drawer full of tooling (probably a hundred pieces or more) that have been ground to a specific profile for grooving, radiusing, relieving, or other profiles not found on standard turning and facing tools. Often times I take an old tool that has a profile close to what I need and regrind it for the new profile. In this case I think the easiest and least expensive method is to take an appropriate size blank and mark the profile on the end using a radius gauge. You can start with one a little larger than the final dimension just to get it roughed in. Once you're close then use the exact size gauge as a pattern and finish the job.

It shouldn't take more than a few minutes for even the least experienced, and it would add an additional skill to your set. The best thing about learning to grind your own tooling is that you'll quickly find that purchasing a tool for a one-off job is in many cases impossible, and when it can be done often increases the cost of the project exponentially.
 
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