For simple tubing joints with small tubing you can just warm the whole area
up to a little below the softening point, turn off the oxygen and soot up
the joint for a little insulation then let it cool in air. For bigger
things you get the final joint done and get it into the oven while it is
still very hot - if you let it cool to room temp you run the real risk of it
fracturing as it cools. Turn the oven on and get it up to temp
ballistically, an hour or two for the big oven in the glass shop at UCR,
hold at the annealing temp so the heat can soak in and everything can get
equilibrated, then cool to room temp over 8-15 hours. Annealing temp
depends on the glass type.
-----
Regards,
Carl Ijames
"RogerN" wrote in message
...
"anorton" wrote in message
m...
You might want to check this out. If you are making large glass apparatus
that you do not want to break easily, you will also need an annealing kiln.
http://www.ilpi.com/glassblowing/index.html
Several years ago I "won" a lot of 11 Fuji digital temperature controllers
on eBay. They have ramping programming capability, set a temperature, a
ramp time and a soak time. I thought I could use an old ceramic kiln and
one of my controllers, set to ramp down over 12 hours or whatever is
recommended. I thought of using that kind of setup for annealing hardened
steel, the ramp has 4 steps that can have ramp times up to something like 99
hours & 59 minutes.
I've also saw some info on flame annealing with the torch, if that would
work OK, I could do that temporarily and kiln anneal a batch at a time with
gentle ramp up, soak & ramp down.
For now, I have some 12" pieces of small tubing and a 12" piece of larger
tubing. If I can join 2 piece of small tubing to get over over 12", I want
to use the glass and stoppers to make a water cooled condenser. It would be
nicer if I could attach nipples to the large glass and just use single hole
stoppers. Of course if I would ever get the skills I could construct the
condenser without using stoppers at all, but I don't have the equipment or
skills for something like that now.
RogerN