On Wednesday, May 08, 2019 08:50:26 PM Crispin Miller crispinmm@...
[sunfish_sailor] wrote:
Nice technique for a heavy-duty gluing dowel!
Just to give a different perspective, you can use a similar technique to hold
up the roof in an underground coal mine (and probably other similar mines) --
use a roof bolter machine to drill a 30 to 72" long hole (sometimes longer,
iirc)(I forget the diameter maybe 1 1/2"?) and then pack the hole with
specially prepared bags of thick epoxy (the bags have separate compartments
for the epoxy and the hardener) then use the roof drill hydraulic pressure to
push a "roof bolt" (which in this case is essentially a 30 to 72" long rebar
(with the typical rebar "pebbled" surface) with a square head on the end.
Pushing the rebar into the hole breaks the bags, then use the drilling
function to spin the rebar (again, I forget, either for 60 or 120 seconds)
then continue to use the hydraulic pressure to hold the square head (and a
steel plate (a 6x6" square "washer") against the roof for another 60 to 120
seconds which allows the expoxy to at least partially cure.
(I probably should have noted that, after cutting a typical 20x20 foot section
of coal and before installing roof bolts, you set temporary roof supports
using timbers cut to the proper length, a wooden half header, and wooden
wedges.)
Works a treat, holds up mountains! ;-) (Well, at least in drift mines -- in
deep mines it holds up the earth's surface ;-)
