Cove cuts?

[Carl Fisher]

Is there a way to do a repeatable cove cut on a metal lathe? I'm thinking of grip sections and the like where now I have to pull them off the metal lathe and go do the cove by hand on another lathe.

 

[bmachin]

Not an expert, but unless you have CNC you probably need a form tool; i.e. a tool ground to the shape of your finished part.

I use a half-round file to shape my sections on my metal lathe.

FWIW,
Bill

 

[Curly]

If you want a section of a circle there are ball cutting jigs that cut a cove when the cutter is forward of the pivot point. Usually mounted to the tool post. If you want a curve that changes form along its length (like an S) you need a tracer lathe.

I'll add that a boring tool can be modified to do the job. Lots of plans in the metal forums and ready made on the market.

 

[farmer]

Cove cut

Can you make a rest that mounts on your tool post to support a skew ?

 

[Carl Fisher]

I have actually looked into the ball cutters but for some reason kept looking for an alternative. I didn't even think about using a longer cutter and pivot point to alter the arc of the cove.

I like the idea of a custom ground profile tool but I'd still have to make a rest for the metal lathe or figure out some way to mount it in a quick release tool holder for the turret.

 

[Mintman]

Carl, I have a tool post that I can mount on my lathe but it's a little awkward. I still end up moving to the wood lathe for shaping and sanding. I'll try to get a pic of it tonight.

 

[mredburn]

a profile cutter could have problems with chatter.

 

[bmachin]

Give Thinbit a call. They are NOT inexpensive, but they do produce a quality product. Their sales people are very helpful and the turnaround has been superb, although everything that I have ordered has been off-the-shelf. Custom tooling would obviously take longer.

FORM-A-GROOVE® External Stackable Multi-Insert Form Tools | THINBIT® Kaiser Tool Company

I have their carbide boring bar and a small i.d. threading tool. Of course a form tool would be custom, but for something as simple as a cove you could probably grind your own.

Bill

 

[Carl Fisher]

a profile cutter could have problems with chatter.

I had considered that when I was thinking about getting some custom profiles ground for my different set grip shapes. Got as far as researching which tool steel to use and someone local to grind and harden for me but didn't go any further than that.

 

[Carl Fisher]

Give Thinbit a call. They are NOT inexpensive, but they do produce a quality product. Their sales people are very helpful and the turnaround has been superb, although everything that I have ordered has been off-the-shelf. Custom tooling would obviously take longer.

FORM-A-GROOVE® External Stackable Multi-Insert Form Tools | THINBIT® Kaiser Tool Company

I have their carbide boring bar and a small i.d. threading tool. Of course a form tool would be custom, but for something as simple as a cove you could probably grind your own.

Bill

That's cool stuff, but probably outside of the budget just browsing the site.

 

[Mintman]

Carl, sorry I meant to post this yesterday.

 

[More4dan]

Here is a simple rest I built for my metal mini lathe.

 

[More4dan]

And the front view.

 

[Curly]

I didn't do as nice a job as the two preceding examples. I took the boring bar holder for the quick release tool post and put a steel bar in it. It was a quick and dirty solution but good enough for shaping a section or two. Transferring to a wood lathe was better.

 

[Carl Fisher]

Sounds like moving it to the wood lathe is still the fastest/easiest method.

Thanks for the tool rest examples. The quick release version may be something I look at down the line when I get a larger lathe with a more substantial quick turret.