How to turn carbide?
 

I've got a small project to do, where I want to turn down the O.D. of
some rock drills by .080".
The problem is they are carbide inserted tips. Kinda as if you'd take
four cemented carbide toolbits and make a countersink out of them.
Don't have a toolpost grinder, and not thrilled about all the carbide
dust anyway.
Someone once mentioned a pressed diamond insert available.. would this
be the way to go, or ceramic, or whatever?
Does anyone here have any experience in turning carbide?
Hope I'm not gonna be at the mercy of the Kennametal or Sandvik
salesman...LOL
Any suggestions are appreciated.
Ron

Ahm no 'spert, but...
I think you gotta *grind* carbide. Fwiu, that's how cutters/drills are made
to begin with.
"Green wheels" are what we use to make lathe tools out of carbide blanks.
They wear very fast, but remove carbide relatively rapidly.
----------------------------
Mr. P.V.'d
formerly Droll Troll
"doo" wrote in message
ups.com...
I've got a small project to do, where I want to turn down the O.D. of
some rock drills by .080".
The problem is they are carbide inserted tips. Kinda as if you'd take
four cemented carbide toolbits and make a countersink out of them.
Don't have a toolpost grinder, and not thrilled about all the carbide
dust anyway.
Someone once mentioned a pressed diamond insert available.. would this
be the way to go, or ceramic, or whatever?
Does anyone here have any experience in turning carbide?
Hope I'm not gonna be at the mercy of the Kennametal or Sandvik
salesman...LOL
Any suggestions are appreciated.
Ron

"Proctologically Violated©®" wrote in message
...
Ahm no 'spert, but...
I think you gotta *grind* carbide. Fwiu, that's how cutters/drills are
made
to begin with.
"Green wheels" are what we use to make lathe tools out of carbide blanks.
They wear very fast, but remove carbide relatively rapidly.

Folks use green wheels, but smart ones use diamond wheels. :-)

The problem with the "green wheels" is that they're not all that much harder
than the carbide, so it's tough on the wheels, the dust from which (silicon
carbide) is very bad for your health, to say nothing of the carbide dust.
The wheels tend to chip the carbide instead of cut it, so the end product
(your lathe tool) leaves a great deal to be desired.

For the OP------turning carbide isn't something that you'd do with success.
It's far too brittle and would chip instead of cut, leaving the trailing
edge a mess, assuming you could come up with a medium that would machine it
at all. It really should be ground with diamond or CBN wheels.

Harold

Dust indeed!
So surprising how "apparently soft" green wheels are compared to grey Al
oxide "rock wheels", yet, the grey wheels just get the carbide hot, while
the green wheel really takes the carbide--and itself!--down.

Surprising also what is making the "hazardous" list. M42 (cobalt steel), is
on there, wrt to grinding. Ditto chromium, etc.

Yeah, diamond wheels....
Open yer wallet.... :)

You can have diamond tools custom made, for actually less than you might
think. We do a repeat specialized facing jobby using custom-made diamond
cup wheels on a surface grinder, from a company in NJ--nice to deal with.
Iffin anyone needs this type of stuff, email me and I'll dig up the partics.

Now the question is, how does one make *diamond tools*?? Abrasive jets &
crazy glue, I guess. :)
----------------------------
Mr. P.V.'d
formerly Droll Troll
"Harold and Susan Vordos" wrote in message
...

"Proctologically Violated©®" wrote in message
...
Ahm no 'spert, but...
I think you gotta *grind* carbide. Fwiu, that's how cutters/drills are
made
to begin with.
"Green wheels" are what we use to make lathe tools out of carbide blanks.
They wear very fast, but remove carbide relatively rapidly.

Folks use green wheels, but smart ones use diamond wheels. :-)

The problem with the "green wheels" is that they're not all that much
harder
than the carbide, so it's tough on the wheels, the dust from which
(silicon
carbide) is very bad for your health, to say nothing of the carbide dust.
The wheels tend to chip the carbide instead of cut it, so the end product
(your lathe tool) leaves a great deal to be desired.

For the OP------turning carbide isn't something that you'd do with
success.
It's far too brittle and would chip instead of cut, leaving the trailing
edge a mess, assuming you could come up with a medium that would machine
it
at all. It really should be ground with diamond or CBN wheels.

Harold

"Proctologically Violated©®" wrote in message
...
Dust indeed!
So surprising how "apparently soft" green wheels are compared to grey Al
oxide "rock wheels", yet, the grey wheels just get the carbide hot, while
the green wheel really takes the carbide--and itself!--down.

You're confusing bond with abrasive hardness. Not the same thing. Silicon
carbide (the green wheels) is much harder than aluminum oxide, but it is
softly bonded so it breaks down rapidly to keep exposing new, sharp grain.
Because it's intended for grinding tungsten carbide, they know the grain
dulls quickly. They color code the wheels so you don't use them for other
purposes, knowing they break down rapidly and wouldn't perform well. The
typical silicon carbide wheel intended for other use is generally a shiny
black color.

Aluminum oxide wheels are bonded much harder, but the grain is too soft to
effectively grind tungsten carbide. The wheel glazes over and quits
cutting, but because it's bonded much harder, doesn't break down very fast
to expose new grains.

Harold

Nothing like a little clarification! Woulda never thought of that! :)
----------------------------
Mr. P.V.'d
formerly Droll Troll
"Harold and Susan Vordos" wrote in message
...

"Proctologically Violated©®" wrote in message
...
Dust indeed!
So surprising how "apparently soft" green wheels are compared to grey Al
oxide "rock wheels", yet, the grey wheels just get the carbide hot, while
the green wheel really takes the carbide--and itself!--down.

You're confusing bond with abrasive hardness. Not the same thing.
Silicon
carbide (the green wheels) is much harder than aluminum oxide, but it is
softly bonded so it breaks down rapidly to keep exposing new, sharp grain.
Because it's intended for grinding tungsten carbide, they know the grain
dulls quickly. They color code the wheels so you don't use them for other
purposes, knowing they break down rapidly and wouldn't perform well.
The
typical silicon carbide wheel intended for other use is generally a shiny
black color.

Aluminum oxide wheels are bonded much harder, but the grain is too soft to
effectively grind tungsten carbide. The wheel glazes over and quits
cutting, but because it's bonded much harder, doesn't break down very fast
to expose new grains.

Harold