View Full Version : O-ring gland cut

12-27-2005, 07:43 AM
I have a small rectangular aluminum part that requires a circular 0.5-inch ID o-ring gland to be cut on one face (static face seal).
What machine (lathe or mill) is best to perform this cut and what type of cutter is used?
A website that illustrates this would be most helpful.
Jeff in Florida

Mike Burdick
12-27-2005, 12:20 PM

This is how I do that sort of thing…

Since you said the part was “small” I’d set it up on the lathe using a 4-jaw chuck. To cut the groove (flat bottom) I use a boring bar holder that will hold a round piece of cold rolled steel that I can machine. For the cutter I buy a HSS drill bit the same size or “wee” bit larger of the thickness of the O-Ring being used and sharpen it flat on the end with the top part cut back so it will have a cutting edge. Do this on the “twist” end as the shank is probably annealed and won’t hold and edge.

Before you cut the drill bit flat use it to drill a hole thru the cold rolled bar and also drill and tap the bar for a setscrew to hold the drill bit. I like to drill the hole at 45 degrees so that my tool post and compound are out of the way. For the depth I usually make it about 15 percent less than the thickness diameter – you may want this different depending on your circumstances.

If your part won’t fit on the lathe, then you will have to use the mill and a boring head.

Anyway, this is an inexpensive way to make a grove for small diameter O-rings. Also, remember to save this special boring bar with bit for future projects!


[This message has been edited by Mike Burdick (edited 12-27-2005).]

12-27-2005, 12:48 PM
Are you going to make just 1 or 100?

For 1 just chuck in 4 jaw and use a single point (HSS) ground to shape.

For 100 use mill and R/T or boring head.


12-27-2005, 07:53 PM
If this is a face sealing application then all you need is a drill bit and an endmill.

Drill the passage hole first and while your on the same center swap out for an endmill of the proper size and plunge it down slowly for 2/3 of the o-rings thickness.

If you need these in production,just buy a counterbore the correct size.

12-28-2005, 04:32 PM
The application is for a couple of prototypes , about 2" x 3", with the expectation of production of 25/year.
I like the idea of using a mill for the passage drill and then follow it up with the o-ring cut.
Weirdscience, so you suggest to just mill a bottoming hole on the same center as the passage hole?
If I understand you, The passage is drilled on the mill and then I do not cut a groove, I mill a blind flat hole the same diameter+ as the OD of the o-ring. That is very intriguing.
Good stuff guys,
Jeff in Florida