Dave Platt wrote in message
...
In article , N_Cook wrote:

Now I've worked out how to make a 5mm diameter hollow end face cutter ,
to
go in a Dremmel.

Diamond-tipped hollow drill bits/saws are commonly available (they're
used for punching holes in ceramics, gemstones, tiles, etc.) and they
work quite nicely on PCB material... they make nice pad-cutters.


--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Nothing so grand as that, I will look out for those, but I was unaware of
them.

Hollow cutting tool
Particularly for Marshall conductive epoxy pcb boards
To isolate valve base pins by cutting into the board around a pin.
A steel sleeve , this one dimensions internal 4mm and external 5.3mm . Cut
eight small
cuts on one end to make a castellated form with Dremmel and .6mm disc.
Grind a rake angle behind each cutting edge. Place a rod inside the other
end to mount in
a drill chuck. Start at an off axis angle and bring up to axial after first
cutting.
Leave soldered joint in place.
As this was actually perhaps a roll pin rathe rthan a sleeve, not a solid
ring in plan,
an axial join line along its length. Found a use for a Dremmel mandrel where
the screw is
sheared off inside the stem. With free hand grinding with the mandrel
rotating in a sleeve
and grinding against a disc brought the diameter of the mandrel support down
to a tight
fit inside this sleeve. Then a plastic filler for the other end and fitted
in a Dremmel.
Perhaps more reliable , repeat with a good mandrel , find a longer screw,
and
some compressible silicone sleeving to grip the inside of the sleeve like
those
Dremmel sanding cylinder holders.
Not necessarily punch through as will be ragged anyway. With a dart point
excavate
around while desoldering the pin .


Owner had previoiusly returned the amp to Marshall for changing those
resistors and general maintainence only. He has exactly the same amp and
components back , only difference is a few holes in the pcb and wiring path
a bit different.