So, who has used one? Seems to me that if the insert and tool holder can
take the cutting force it should be able to give a pretty good finish
even with a pretty aggressive feed.

On Wed, 7 Feb 2018 10:13:10 -0700, Bob La Londe
wrote:

So, who has used one? Seems to me that if the insert and tool holder can
take the cutting force it should be able to give a pretty good finish
even with a pretty aggressive feed.

It does. You just need a pretty solid setup so the tool doesn't skate.
It applies a lot of pressure to the workpiece.

I had a few samples I got from Valenite, I think, in micrograin
carbide amd with a sharp edge. I could cut mild steel with them on my
old SB lathe. But most round inserts aren't so free-cutting.

--
Ed Huntress

"Ed Huntress" wrote in message
...
On Wed, 7 Feb 2018 10:13:10 -0700, Bob La Londe
wrote:

So, who has used one? Seems to me that if the insert and tool holder
can
take the cutting force it should be able to give a pretty good
finish
even with a pretty aggressive feed.

It does. You just need a pretty solid setup so the tool doesn't
skate.
It applies a lot of pressure to the workpiece.

I had a few samples I got from Valenite, I think, in micrograin
carbide amd with a sharp edge. I could cut mild steel with them on
my
old SB lathe. But most round inserts aren't so free-cutting.

--
Ed Huntress

I ground some half-round HSS bits to cut wire rope grooves in aluminum
and stainless pulley sheaves, which I made narrower and larger in
diameter than commercial pulleys for fiber rope. They do leave a
smooth finish but I had to wiggle them back and forth to reduce the
chip width instead of plunging straight in, or they would chatter
excessively on my old SB.
-jsw

On 07/02/18 18:34, Jim Wilkins wrote:
"Ed Huntress" wrote in message
...
On Wed, 7 Feb 2018 10:13:10 -0700, Bob La Londe
wrote:

So, who has used one? Seems to me that if the insert and tool holder
can
take the cutting force it should be able to give a pretty good
finish
even with a pretty aggressive feed.
It does. You just need a pretty solid setup so the tool doesn't
skate.
It applies a lot of pressure to the workpiece.

I had a few samples I got from Valenite, I think, in micrograin
carbide amd with a sharp edge. I could cut mild steel with them on
my
old SB lathe. But most round inserts aren't so free-cutting.

--
Ed Huntress
I ground some half-round HSS bits to cut wire rope grooves in aluminum
and stainless pulley sheaves, which I made narrower and larger in
diameter than commercial pulleys for fiber rope. They do leave a
smooth finish but I had to wiggle them back and forth to reduce the
chip width instead of plunging straight in, or they would chatter
excessively on my old SB.
-jsw


While my Harrison M300 will take a fair cut and the largest radius bit I
have is 8mm radius these days when I make the likes of bending formers
for my rotary draw tube bender I use the rotary table on the BP as it is
far easier and less prone to issues.

On Wed, 7 Feb 2018 10:13:10 -0700, Bob La Londe
wrote:

So, who has used one? Seems to me that if the insert and tool holder can
take the cutting force it should be able to give a pretty good finish
even with a pretty aggressive feed.

Adding to that, round inserts are usually made either for milling or
for rough-turning with rigid machines and a lot of horsepower. But you
get a "wiping" effect because of the geometry, and some applications
allow them to be used as really aggressive (and very strong) roughers,
while producing an adequate finish for many applications at the same
time, in a single pass.

Watch for chatter. As Jim mentioned, that's a limiting factor.
Chip-breaking is another.

BTW, for single-pass turning with rigid lathes, wiper inserts are the
coolest thing going. Or they were, a few years ago, when I last wrote
about them. I watched them at work at Sandvik (in NJ), and they were
fantastic.

--
Ed Huntress

On Wed, 7 Feb 2018 10:13:10 -0700, Bob La Londe
wrote:

So, who has used one? Seems to me that if the insert and tool holder can
take the cutting force it should be able to give a pretty good finish
even with a pretty aggressive feed.

I use them regularly...but primarily for radius cutting. Remember that
the actual cutting surface is pretty big..far bigger than .030 unless
you are doing a skim cut.

They do work pretty well if your machine is capable of supplying the
torque to get in and cut.

They are VERY good for aluminum where cutting pressures is moot.

Just remember to feed only as fast as it doesnt leave a nice grooved
surface.

Gunner

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