External O-Ring Groove Lathe Tools?

[MaverickNH]

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

 

[mmcmdl]

Thin bits .

ThinBIT® Cutting Tools

Kaiser Tool Company, Inc. THINBIT® manufactures precision cutting tools, inserts and toolholders for lathe. Coatings, form tools, and special configurations available.

www.thinbit.com

 

[MaverickNH]

It comes to mind - I’ve see squared and radiused grooves cut for O-Rings in various build videos. I suppose squared groove tools are more broadly useful.

With tools like those pictured below, do they cut only on the plunge? It looks like it…

 

[mmcmdl]

Square inserts can be ground if needed .

 

[mmcmdl]

With tools like those pictured below, do they cut only on the plunge? It looks like it…

They are made for plunge cutting but will also traverse at a minimum depth . Nice tools , I'm sure there are cheaper imitations but these have been around for quite some time . Nice for cnc machines too !

 

[RaisedByWolves]

I would just use a cutoff blade.

Cheap and easy to grind to whatever thickness you need.

 

[Flyinfool]

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.

 

[MrWhoopee]

ThinBITs are the go to if you need precision, grind a parting blade if you need economy.
I recently needed to cut some retaining ring grooves, I ground a tool.

 

[toprecyler]

I just use a parting tool blade, most of the time. Just plunge, move over 2/3rds of width of parting tool till wide enough for ORing width, leaving .005 to .01” for a clean up pass.

My tool of choice is .125” wide. I do have a couple insert parting off tools, that work well too. Those are usually a bit more stable for cuts with the carriage.

Note, oring grooves for sealing purposes, are usually approximately 20% wider than width of oring, to allow for squish of O-ring. You will probably want the groove width the size, or slightly under size so the oring will seat nicely in the groove. So you may have to grind your cutoff tool a bit narrow to fit your oring of choosing.


Sent from my iPhone using Tapatalk

 

[benmychree]

Real O ring grooves are slightly wider than the O ring width as mentioned above, and have slightly angled sides and radiused corners in the bottom of the groove.