Machining a square section O ring groove

[Chris Wilson]

I need to machine a round billet of stainless steel on its flat face with a
square section groove to take an O ring. The OD needs to be about 60 mm,
the ID 50 mm and the depth of the groove 4 mm. I have a smallish (11 inch
swing Harrison) lathe and a Bridgeport universal mill, but very limited
tooling as I am a novice. What is the easiest way to attack this, the
billet is cicular on its OD, can be gripped in the chuch of the lathe, and
the groove will be concentric with the OD. I also have hand wheel roatable
table for the Bridgeport, although I haven't used it and am not even sure
of its proper name....rotary table? :)

I would probably have to buy or make a cutting tool for the lathe as I see
nothing obviously suitable amongst the stuff I have.

Thanks, the thing I need to groove was expensive and I don't want to wreck
it going in blind.

Thanks.

[Bill Noble]

you should be able to cut this on your lathe using a "trepanning" tool - you
can grind your own

"Chris Wilson" <nos...@invalid.com> wrote in message
news:j55mxpbvincn.borxb9wwjynp$.dlg@40tude.net...

[Tim Wescott]

If that nasty old rotary table confuses you, I'll take care of it for
you :-).

Trepan. You need a trepanning tool, which is much like a cutoff tool
except that it accounts for the curve of the cut it makes. Then you get
to find out how rigid your lathe is.

--
www.wescottdesign.com

[Jim Wilkins]

On Dec 27, 12:29 pm, Chris Wilson <nos...@invalid.com> wrote:
> I need to machine a round billet of stainless steel on its flat face with a
> square section groove to take an O ring. The OD needs to be about 60 mm,
> the ID 50 mm and the depth of the groove 4 mm. I have a smallish (11 inch

> swing Harrison) lathe....

If you aren't comfortable cutting straight in with a square tool you
could grind a triangular bit like a threading tool but about 20 to 30
degrees between sides and cut in a little at a time with it. Angle the
tool so only the tip cuts, run in with the carriage until it starts to
complain, back off a little and cut in or out almost to the other
wall. Once you have roughed out most of the groove you can use a
square-ended bit narrower than the slot so only one side cuts at a
time.

The pointed tool I use is rounded on the end and nearly flat on top so
it cuts in both directions. The angle is ~30 degrees. I use it to
rough out belt grooves on mandrel-mounted pulleys, which won't stand
much cutting force.

jsw

[whit3rd]

On Dec 27, 9:29 am, Chris Wilson <nos...@invalid.com> wrote:
> I need to machine a round billet of stainless steel on its flat face with a
> square section groove to take an O ring.

> I would probably have to buy or make a cutting tool for the lathe as I see

> nothing obviously suitable amongst the stuff I have.

You'd best use HSS and low cutting speed, and the lathe is
definitely better than the rotary table and mill. The O-ring
has to seal against the bottom face, so the finish of that
part of the cut is critical. Sidewalls don't need to be
exactly at 90 degrees, usually they're low-tolerance.

[clarkm...@gmail.com]

Is the O ring groove on the inside diameter of the big tube?
If so I have done it the wrong way in the past.
I think to cut a gland, you are supposed to have a boring bare bit
ground to the correct width, and just make one cut.