In article . com,
wrote:

GREAT explanation Richard. That's exactly the way I understood it too
(and why I am trying to be pretty careful with my ramp rates). If you
ramp up too fast then it could cure before it has a chance to get rid
of the voids. I'm not exactly sure what happens if you ramp up too
slow but it must be a bad thing


The more I think about this, and based on what Richard and others have
said, the more I think that you don't need a sophisticated controller,
particularly in light of your financial constraints. Maybe a
well-insulated box, (oven) with the correct size heater, would work
fine. You might have to experiment a bit with heater size to fine tune
it. And, you could put in three small heaters with external switches.
Use all three for heat up, two for holding temp, and one for
decelerating the down ramp. A bit of experimenting with different
wattages might do the trick nicely.