I once watched a contractor dry cut rebar with a diamond blade using a
cut-off saw. I wanted to tell him you can't do that, but he was quite
burly, so I left it alone.
He said it was a diamond blade, so I'll never know for sure.

I presume diamond blades work in cutting reinforced concrete because the
concrete is there to temper the feed rate..

Roland


On 10 May 2016 at 17:47, Dave Cole <linuxcncro...@gmail.com> wrote:

> I've been doing the controls for a manufacturer of large core drill
> machines for about 10 years. The machines are made to drill holes in
> concrete structures that make up sewer systems.
> The machines can drill up to 60" holes using diamond segmented tipped bits.
>
> Diamond bits work great for concrete and stone and they do ok when
> sawing through the wire reinforcement in the concrete as well (up to
> about 1/2" rebar reinforcement).
> Water is always used with those bits for maximum life.   However they
> don't need a lot of water.  Just enough to wash away the grindings.
> With smaller bits (12-24") in diameter, the machines can achieve feed
> rates of 4-5 inches per minute even when chewing through wire
> reinforcement.   Diamond tipped saw blade "teeth" are really tiny
> diamonds in an alloy matrix which rubs against the material to be cut.
> Its really more of a grinding process than a cutting process.   A good
> diamond tipped concrete core drill can drill through 100+ feet of
> concrete before needing to be re-tipped if the core drill is treated
> properly.
>
> I've never heard of diamond bits being used to solely cut cast iron.   I
> would think that Carbide or HSS would be preferable.
>
> Dave
>
> On 5/9/2016 11:13 PM, Gene Heskett wrote:
> > On Monday 09 May 2016 22:40:45 andy pugh wrote:
> >
> >> I am not an expert in diamond sawing, so take that as a caveat.
> >> However, as far as I know diamond turning of iron-based materials is
> >> almost never done. For iron-based materials the abrasive of choice is
> >> CBN.
> >> The reason for this is, as I understand it, is because carbon is
> >> soluble in iron. In fact the whole marvellous thing that is ferrous
> >> metallurgy is just playing games with the various things that
> >> solutions of carbon dissolved in iron can do when you heat and cool
> >> them.
> >>
> >> Diamond turning of aluminium and copper alloy parts has been standard
> >> for 50 years or more. You won't find many references to
> >> diamond-turning of iron alloys.
> > Thanks Andy.  I should point out that I am not turning it just yet, but
> > sawing off a slice, nominally 1.75" thick, that I can turn, eventually
> > into a block the same height as the compound carriage is, to add some
> > mass to the crossfeed, and to offset the QC holder to the rear and
> > right, thereby putting the typical cutting tool much closer to the
> > center of the Z carriage so the cutting forces are essentially straight
> > down on the center of the Z carriage.  And that I am not achieving a
> > temperature where the carbon (in the diamond dust) can dissolve into the
> > iron.  At no time has the blade or the workpiece been heated to the
> > point I can't rest my hand on either.  Slow, but it seems to be a pretty
> > precise way to do it, so far.  Got a huge pile of grey cast iron dust
> > though.
> >
> > Ignore that thumping sound, thats just me, knocking on wood. ;-)
> >
> > Cheers, Gene Heskett
>
>
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