On May 16, 4:26*am, "Mike Marlow"
wrote:
js.b1 wrote:
Diamond blade plus angle grinder on a treet stump killed someone
recently (kickback into neck). Suicidal.

Bull. *Diamond wheel on an angle grinder is the wrong combination, but not
for that reason. *Kickback has nothing to do with the wheel on the grinder,

****wit.

A diamond disc will not cut wood due to the mimimal depth of the
cutting surfaces, it will instead burn through whilst spinning at
circa 10,000 RPM.

A diamond disc with sintered tabs, several long teeth interspersed by
gaps, will snag on the wood fibres - flinging unsecured wood at some
function of the 80m/sec disc speed, kicking back off sufficiently
immovable wood or shredding wood into a fibrous pulp rather than
efficiently cutting. With sintered tab on wood there is some risk of
ejecting a tab or a limited risk of catastrophic disc fracturing from
a tab gap (most discs have the tab slot ending at a circular hole to
reduce crack propogation across the disc causing separation which at
circa 10,000rpm would be unpleasant).

A diamond disc that is continuous (does not have a tabbed perimeter)
will just bounce off the surface or burn through.


This is exactly how someone killed themselves with a diamond disc in
an angle grinder, it kicked back off a tree stump and embedded itself
in their neck severing an artery. Most likely a tabbed diamond disc
where the slots snagged on a particularly resilient group of wood
fibres so launching the grinder up into the victim's neck.

Any blade for wood cutting at angle-grinder RPM will need to have a
very robust disc construction, very robust teeth to resist the peak
shear forces along with an appropriate tip cutting angle, and large
inter teeth gap to handle the extremely high material ejection levels
at such high RPM. That is to say teeth gaps of several millimetres
compared to the sub-milimetre gap for diamond cutting brick particle
ejection.


A reciprocating saw more typically just has one blade that simply, well....
reciprocates.

Alligator saw has double blades, demolition saw has single blade. An
alligator saw is a lot more useful to a DIYer.