Retaining Ring Groove Tool

What does everyone use for cutting retaining ring grooves in shafts? Specifically, I’m looking for something to provide a properly toleranced groove for a 1/2" shaft, which is .039" wide x .468" in diam. All the cutting tools we own are much wider than this. I know you can custom grind your own tools from HSS but I have no experience with this. Something off the shelf would be preferred.

Big Kaiser Thinbit SGI039D5 for aluminum SGI039D2 for ferrous metals.

You will need p/n SFT12Lfor the holder (you can select a different shank size if necessary)

Western Tool and Supply in Portland carries them. You can probably find other local distributors.

It’s easy to grind a piece of HSS cutter stock to do the job. Keep your micrometer caliper handy and check the size often. The narrow piece only needs to be about 1/4" long. If you screw it up, grind it off and start over. I made one up yesterday by grinding down a piece of .100 parting tool because it was quicker than finding the one I made during build which is double ended - one for 1/2 and the other for 3/8. It took less than 5 minutes and when I was done, I just ground it back to square again. A LOT cheaper than buying a special holder and cutter.

Although it doesn’t discuss exactly how to cut a retainer groove. “How to Run A Lathe” by South Bend Lathe Works is a good basic how to on operating a lathe. Originally published in early 1900s & updated through the years. Early versions can be found as a PDF download or ordered cheaply as a reprint. Along with a Machinery Handbook, it enough to do anything you can do (which is a lot) with a small lathe.

It has a section on grinding bits.

I view grinding tools as a stopgap measure if you absolutely need to get it done now and you can’t go buy the tool you need.

It’s so much nicer working with inserted grooving tools, especially in small sizes.


Even properly ground, the ground tool just doesn’t last as long as the insert tool.

We do a lot of snap rings, so this saves us a good deal of time.

MSC Direct is a good resource for tooling. There may even be a branch local to you so you don’t have to pay shipping. The local branch might even be willing to sponsor your team … :wink:

We use a Nikcole Mini-Systems grooving tool and it works well. Enco sells it along with a page full of cutter inserts. Just saw this link through amazon:

We do all ours with a HSS blank that we grind. It’s never been a problem. This past season, we started doing the ones we could in a vertical collet holder in the CNC using a slitting saw to go around it. Came out great.

Also, our kids break a lot of the grooving inserts by running them sideways into the workpiece. Much easier to replace them than to grind a new tool.

Thanks Cory, this is perfect. What do you use for cutting fluid with these (or do you cut dry)?

The amount of material removed is so small that there’s not much need for cutting fluid.