They are probably made one of three waysNovember 21 2010 at 9:49 PM
theotherChris (Login theotherChris)
from IP address 220.127.116.11
Response to Material
1) hydroformed. This would be the least expensive and could be done with a simple grease gun providing the pressure to drive the aluminum blank into the female die.
2) male die with the aluminium pressed over it with a big block of rubber. Need a big press and a big block of rubber. I have the book that shows how to calculate the force used based on the material type and the size. I have a big press but it might not be big enough. One thing better than having a big press is having a friend with a bigger press....and I do.
3) male die with a female die pressed together with a big press. This would be the most expensive as the male needs to be accurately guided over the female.
I imagine that the material is somewhere around 32 to 40 thousandths thick and is of an annealed condition at the start of manufacture. I would imagine 3003-O would be a good starting point. The material will work harden during the forming process and then will continue to age harden....
Neil, are there stretch/tooling marks in the aluminium that pokes out from under the cork?