On Sat, 3 May 2008 09:00:25 -0700 (PDT), John Martin
wrote:

On May 2, 12:25*pm, Bob Engelhardt wrote:
http://home.comcast.net/~bobengelhar...rill2.jpg(43kB)

I found this bit at the dump. *It has a tapered shank & is marked "star
- hammer - twist". *It has a chisel point, not a cutting lip, so it
clearly does impact cutting & hence (?) is for masonry. *But it is not
carbide tipped! *It has some rust, so it can't be solid carbide, can it?

So, I guess the question is: is there some steel alloy that is used for
* masonry impact drilling?

Thanks,
Bob

It's steel, not carbide.

The tapered shank of that bit fit into a hexagonal or octagonal
holder, maybe 6" long. The holder had a slot cut in it which allowed
you to use a wedge to remove the bit - just as in removing a Morse
taper bit. The holder was hit by a hammer, and rotated between hits.
The advantage of this over a regular star drill was that you could
have a big, solid shank on a small diameter bit. The bits were
sometimes spiral, sometimes straight.

By the way, common star drills ain't so common anymore. I needed to
hang a couple of shelves in the basement the other day. Figured 5/16"
screws would be fine, so I grabbed a box of machine screw caulking
anchors I'd had for years. Hmmm - full box. Hole size 5/8". Looked
for a 5/8" star drill. Plenty of 1/4", 3/8", 1/2", 3/4", 1" and
larger, but no 5/8". No problem, I'll just pick one up at the
hardware store. The third try - the biggest hardware store in
Portland, Maine, serves mostly commercial customers - actually had
three sizes. None of the sales people had any idea what a star drill
was, even in the store that had them. No 5/8", of course. So I ended
up using 3/8" screws, which need 3/4" holes. Now I knew why the one
box was full, and the other almost empty....

John Martin


My "ground rod driver" is an elderly Black and Decker hammer "drill"
No rotary motion at all, but simply bangbangbang. It came with a full
compliment of star drills and holders as well as the holders that you
grab and turn.

Works as good as a rivet gun for driving ground rods

$10 at an estate sale. In the factory metal box with all the
accessories


Gunner

Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.