Sherline lathe radius tool

Machine Shop
#1

I experimented with the Sherline lathe radius tool. It was easy to set up and easy to use - although I admit I was going for a cosmetic radius, not something particularly precise. I started with a cylinder of the correct diameter, which makes the radiusing simple. I was too lazy to mark the correct z-axis starting point for the radius but that would have been easy enough to do.

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This radius-cutting tool pivots vertically over the top of the turning, unlike a conventional radius cut tool which operates horizontally.

The one caution I would have is that the length of the work piece needs to be long enough so the radius cutter doesn’t hit the chuck jaws. There is nothing to prevent it from swiveling backward and hitting the chuck jaws while they are turning. My piece was about 1.5" long and the cutter was precariously close to those spinning jaws. Both photos shows it after I retracted it from the cutting position - on the final cutting pass it was probably 0.050" or less from the jaws.

The surface finish on the finished radius was rough, but that may likely be because I was cutting acrylic.

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#2

I did it on aluminum and it does a good job so it was likely the material. The Coulchester radius tool also looked terrible on Delrin plastic.

#3

I agree. I suspect the tool was perhaps just a little dull. The acrylic got quite warm cutting the radius, even though I took very light cuts. I’m sure that the warmness of the acrylic was what created the poor surface finish.

#4

Awesome. Great description. I purchased a 5/8" rod of copper to make beads, and a rounded side would look great. @John_Marlow what was the wide the of hole in the center? Will a 5/8" diameter rod fit there? I could cut it into smaller pieces if need be, but I’d end up with more waste than I’d like.

#5

The hole in the headstock is not large. it is only cut to accommodate the draw bar (3/8 - 1/2?).
The radius tool has a maximum size of 1" diameter. So the short of it is you’re gonna have some waste from the 3 jaw chuck.

#6

Understood. The rod is actually 1/2" not 5/8, but either way it looks like cutting it to size is the best option. Thanks to both of you. I’m really looking forward to working this copper on that lathe.

#7

Copper is typically a tough metal to machine, it gets very gummy, so expect to practice quite a bit before getting something useable. You will likely want to grind your own lathe bit with geometry specific for copper.

If possible, using brass would be much easier, and brass can be copper plated very easily as well.

#8

Don’t cut any pieces shorter than 2". In fact, don’t cut more than one until we figure out the best length. If it’s shorter than 2" you run a serious risk of hitting the moving chuck jaws with the radius cutter. Mine was 1.5" long and I was dangerously close to the chuck - maybe 0.050", maybe 0.030". Mine was also 5/8" diameter and remember you will need half of the diameter to position the cutter. If it’s longer than 2" you might be able to get the second radius started with the radius cutter as well. But we need to make sure the workpiece isn’t too long to hold it well.

If it is drilled first, when you cut the second radius you can probably put a live center into the drill hole to give it some stability.

Why don’t you cut a wooden dowel to “length” and just experiment with positioning it? Don’t actually turn the wood, but put it into the chuck and put the radius cutter on the lathe and see how much clearance you need. Or cut it longer, make some Sharpie marks on it at some known lengths and that should give you an idea how long it needs to be in order for the cutter to clear the chuck.

EDIT: You might also be able to use the knurling tool around the middle part of each bead.

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#9

Spot on, I’d love some hands on time with you if our schedules line up and you’re willing.

Here’s the begleri I want to be able to make. Any decoration on the outside is just plumage, what matters is the size/weight, and that it be drilled out properly. You cant’ see it in the photo, but it has a countersunk hole. the smaller hole being just large enough to fit some paracord though with a knot on the end holding it.

I’d start with just adding a bevel to the edges rather than trying to round out one side like you’ve done.

begleri_copper

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