I am trying to make a pipe out of glass beer bottle using blowtorch makes good bowl but breaks on cooling idea
Answers:
Yo:
You have a thermal shock problem. Pyrex glass cools in air but it has a very low coefficienr of expansion. It also has a lot of Boron in its mix. But most glass is not pyrex.
The trick is to cool the glass very slowly. The industry also cools their glass very slowly ,after working with it. ( e.g. after glass blowing, casting, pressing, or blow molding.)
They place the completed pieces into an oven called a lehr, to slowly cool the glass down to room temperature.
Slow cooling eliminates the strain in the glass set up after the above manufacturing procedures.
I would lower the emperature of the oven from its max (500 degrees F.), to room temperature at the rate of 10 degrees every hour. (you might get away with 15 degrees, try it and see). Is such annealing a pain; you bet. So get some buddies to take turns babysitting the oven, 24 hours a day for 50 hours, or rig up a device that lowers the temperature automatically..
I cannot give you more precise time and temperatures because I do not know the composition of your glass nor the configuration of your final product.
Please note that the kitchen oven's maximum temperature may not be hot enough. (if so, contact a potter or copper enameller and do it in their kilns.
Good luck.
Dan the Anewers-Man.
Other answers:
must cool very slow
must cool very slow
well cool it down slow and not fast.
Remember glass will explode and hurt you and other people.
use oven to preheat and to post heat.
sweety be careful and wear goggles. And if it works out be sure to wear goggles while using it too. Maybe the glass in beer bottles has a different type of chemical or molecule make up than the glass used in other pipes.
NOT going to ask why here, but try using the returnable type bottle, if you are using the disposable. They're generally more durable and made with thicker glass - should cool slower, etc.
Go to a 'Head Shop' and buy your weed pipe just like the rest of them.
After heating, quickly cover it with sand to slow the cooling process.