Re: G-10 Disk purchasing/drilling

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Edward Wingate by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ewing7-at-rochester.rr-dot-com>

Tesla list wrote:
> 
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> 
> Hi Scott,
> 
> G-10 drills and machines very easily with cobalt alloy mill cutters and
> drills.  They wear much faster than say milling LE, but the cutters last a
> reasonable length of time.  You pay the pros more for the high tool wear and
> probably the nasty dust created.  I like the titanium nitride coated cobalt
> cutters the best.  High speed steel is probably not practical for more
than one
> quick hole (per bit!).

<snip>  

Terry,

I've had a bit of experience machining G-10 and use only high speed
steel drills on G-10, they work just fine for a hundred holes or more
without sharpening. A dull drill is actually better than a sharp one
for drilling G-10 because the dull drill won't catch when penetrating
the other side of the material. I deliberately stone the sharp edges
on a new drill to an approximate 1/64" flat with a reamer stone before
using to avoid the catching problem. This method also works well on
other plastics to avoid the nasty and hazardous catching problem.

I also use standard high speed steel reamers and taps on G-10 and they
hold up just fine.

> To make a long story short, if you going to cut the hardest materials
> available, you will need the hardest tools available.  One nice thing is that
> cobalt drills drill wood just fine too and unless you loose or break
them, they
> will last forever ;-))  I "only" get cobalt tools now days...  Always wear
> safety glasses with cobalt tools (even if drilling just wood) since if
they do
> break, they explosively shatter in nasty shards!  But they don't break
easily.
> I have never had to sharpen one, but I imagine it is darn near impossible
> unless you have some fancy diamond setup.

 
> Cheers,
> 
>         Terry

Cobalt alloy is not that special and only marginally better than high
speed for most uses. It can be easily sharpened on any grinder that
will sharpen high speed steel. Diamond or green wheels are only
necessary for carbide tools.

Safety glasses should be worn when using any cutting tool!! Any of
them will shatter under the right conditions. Safety glasses are
second nature to me because I can't see what I'm doing without them!
:^)

Ed Wingate RATCB