Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?

Does one use ordinary masonry drills?

Any undertakers out there?

Airy R. Bean wrote:
Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?

Does one use ordinary masonry drills?

Any undertakers out there?

A quick Google search on "drill marble slab" came up with hits to
support my first idea for drilling the marble: use a copper tube
the diameter of the hole you want, in a drill press at _low_ speed,
with lots of (fairly coarse) abrasive powder, lots of water, and low
pressure on the drill bit. It's the same rig I use for drilling glass.

You will want a stream of running water so that the bit is kept cool
and lubricated, and the abrasive doesn't turn into a hard paste.
It will be messy; if you can put the slab in a cookie tin or
aluminum-foil pan, and run the excess out through a tube, that will
help. You also could build a modeling-clay dam around the hole.

It's almost impossible to over-lubricate, but it's really easy to
under-lubricate.

See http://www.shopsmartxpress.com/Ameri...lt.htm?M9a.htm
for some useful tips.

Polishing is easy: coarse-to-fine sandpaper, then buff with increasingly
fine powdered abrasive, up through white rouge or so. You have to get
all the old abrasive out of the polishing tool before you put the new,
finer abrasive in -- but you knew that.

Marble is rather soft, though quite abrasive, and so it's easy to
take off more than is necessary.

--
Mike Andrews

Tired old sysadmin

"Airy R. Bean" wrote in message ...
Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?

Does one use ordinary masonry drills?

Any undertakers out there?

If you will stop by any trophy shop you can get all sorts of marble
,color,shape size etc. quite reasonable too. may already have holes
that you can use. Harold W4PQW

"Airy R. Bean" wrote in message
...
Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?

Does one use ordinary masonry drills?

Any undertakers out there?


An ordinary masonry drill is perfect.It goes through it like cheese. The
material is basically quite soft and can be easily shaped with an angle
grinder and a cheap diamond cutting disc (those for cutting bricks, flags
etc) . For final levelling use various grades of car 'wet-n-dry' (Silicon
Carbide paper) and finish using Silicon Carbide (or even diamond!) 'lapping
paste' slurries.
(nb. for rust stains soak in oxalic acid)
regards
john

Good idea!

wrote in message
om...
"Airy R. Bean" wrote in message
...
Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?
Does one use ordinary masonry drills?
Any undertakers out there?

If you will stop by any trophy shop you can get all sorts of marble
,color,shape size etc. quite reasonable too. may already have holes
that you can use. Harold W4PQW

OK - I'll try that out on some off-cuts, assuming that such
things are available.

Otherwise - I'm collecting various bits of metal to make up a
bug key but am distracted by vertical antenna and its ATU.

I am trying to conceive of a minimal switching scheme to accommodate
the 10 ATU configurations discovered so far....
Straight through
Series C
Series L
Series C-L
"L" network with C on TX side
"L" network with C on ant side
"PI" network
"T" network
Parallel tank, series fed
Parallel tank, parallel fed

"john jardine" wrote in message
...
"Airy R. Bean" wrote in message
...
Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?
Does one use ordinary masonry drills?
Any undertakers out there?
An ordinary masonry drill is perfect.It goes through it like cheese. The
material is basically quite soft and can be easily shaped with an angle
grinder and a cheap diamond cutting disc (those for cutting bricks, flags
etc) . For final levelling use various grades of car 'wet-n-dry'
(Silicon
Carbide paper) and finish using Silicon Carbide (or even diamond!)
'lapping
paste' slurries.
(nb. for rust stains soak in oxalic acid)
regards
john

Presumably also, therefore, with the miniature grinding
wheels of the "Dremel" style?

"john jardine" wrote in message
...material is basically quite soft and can be easily shaped with an angle
grinder....

In article ,
"Airy R. Bean" wrote:

Good idea!

wrote in message
om...
"Airy R. Bean" wrote in message
...
Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?
Does one use ordinary masonry drills?
Any undertakers out there?

If you will stop by any trophy shop you can get all sorts of marble
,color,shape size etc. quite reasonable too. may already have holes
that you can use. Harold W4PQW



I get my used marble from our town's recycling center. You'd be
surprised how many "trophies" are thrown out. I find the side I want and
disassemble it. I even use them for heat blocks when I am doing some
heavy duty soldering. If they crack, I toss them. And...the price is
right!

Al

Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?

Does one use ordinary masonry drills?

Any undertakers out there?
==============================
Yes that will do . I drilled a slate base (similar to marble ) for a pump
key .
It might be helpful to drill with the marble immersed in water.
This method also enables drilling in glass , for example to fit a
feed-through for an antenna (single glazing of course)

Frank GM0CSZ / KN6WH

I'll make up some switches out of brass rod - what I
have in mind is something like a large banana plug & socket
combination activated by nylon or PTFE rods. (I don't envisage
one FG rotary switch - I'll do it with separate switches,
possibly with some interlocking along the lines of
old railway signal box practice - I've enough books here
on that subject!

Primary doodles indicate that the antenna could be left
permanently connected to the inductor and one of the C's,
except in the case of a "T" network when it needs to be
connected to the other end of the said C.

There won't be any relays. The vertical antenna to the base
of which the ATU will be directly coupled is about 10 ft from
the shack and what I have in mind to use is a series of
activating rods - cunningly hidden/faced by a small picket fence.

The only area of development I haven't yet sussed out is how
to pass the operating rods into and out of a sealed (to keep
out the rain) chamber. Perhaps something like the stern
gland of a ship's propeller shaft might come into play here.

"john jardine" wrote in message
...
The 'select 1 of 10' ATU would seem a grade 1 mechanical-electrical
juggernaut of switches, relays?, screening cans, adjustable inductors
(roller coasters?), variables caps, connectors and knobs. I wish you a
interesting journey :-).