I tried my homemade vacforming machine last night with disappointing levels of success.
I drilled a 32mm hole in the side of the box and attached my DeWalt shop vacuum.
I then clamped a sheet of 4mm acrylic into the holding frame
and placed an inverted ceramic pot on the vac bed as a test pattern:
And placed the sheet in the oven at gas mark 8 for 10mins. I was hoping to observe the sheet and, when it started to sag, remove it. The problem I had was that the sheet was too thick and didn't get hot enough before the MDF mount I was using started to char.
As the kitchen filled with the smell of cooking MDF I decided to give it a try anyway:
The thick, partially heated sheet was sucked down by the bed but was not hot enough to be pulled down onto the sides of the pattern. As a result I got this:
I also noted that the MDF mount had shrunk and was no longer gripping the sheet.
Next time I am going to:
1. Use thinner 2mm acrylic.
2. Make a metal mounting frame which will neither shrink nor smell.
3. Drill some more holes in the bed.
Going to be a while before attempt 2, my RepRap bits turned up today ;o)