Thanks for the feedback.
We have been looking for used ovens but have been unsuccesful finding a unit big enough to meet our needs.
The homemade unit we have seen is 8Ft x18Ft, it has about a 36" opening with an automated door. You bring the temp inside up to 350F and slide the plex in, once at the right temp you pull it out, place it over the form and hit the switch. Bam, pan face, just trim and paint as needed.
I was hoping someone on this forum had plans or some insight as to how to fabricate one. The scissor lift is not nessassary for this type of unit. and the guy we know that made his made hundreds of diffrent faces using it.
We are fabricators so it should be easy enough to make with a little direction.
8ft x 18ft??!!!
At that size your are talking about an EPIC amount of heating elements and truly horrific power consumption. We fabricated our own machine which heats a pretty big surface area.... so I thought. Compared to what you are proposing it appears our machine little more than a kitchen toaster.
To heat around 4ft x 4ft it takes us 12KW of power... this amount of heating power works pretty good and it's exactly what our heating element manufacturer recommended for plastic heating/ forming. For your continental sized machine you're looking at a peak power consumption of almost 100kw... that is a LOT of juice which a standard commercial power supply probably won't be able to cope with... worth checking the max KW peak your supply WILL take and then design a machine from there back.
Wiring the elements is something which takes a lot of care and attention to detail. You will want to zone your elements, this allows you to split the power load down from one cable which would be the diameter of an elephant's leg into cable sizes which are more manageable. This needs careful planning... ideally your zones should radiate out from the smallest sheet size you want to form to the biggest... that way you only need switch on the elements required for the sheet size at hand.
Wiring this monster oven isn't something I'd relish... that's a huge amount of power and a serious amount of heat.
We form EVERYTHING inside a stainless steel clamp frame because a sheet of any plastic at forming temp is a sheet of rubbery film which has no dimensional stability whatsoever... drag it out of the oven manually and it'll stretch, warp and go everywhere. If your mate does drag around sheets of red hot plastic then he's in a very small minority; everyone else either pushes the mould former up from under the sheet or drapes the sheet over from above.... we do the latter.
The next thing is vac pumps... you want something BIG, something which can pull and maintain vacuum for a long time. There are various types but I'd be looking for a big blower type or a linked batch of proper vac pumps... we use a chunking great 400v Vac pump on our machine. You can never, ever have TOO much vacuum but you can always have to little. If you are forming a large pan face with insufficient pump "pull" there isn't going to be much to see... your pump needs to break the last vestiges of resistance left in the hot sheet which just won't happen with a weedy little pump. All pumps are adjustable so you can turn down the power of a big pump.
Mould manufacture and finish is a whole different can of worms... it's not as easy and straightforward as it sounds.
Personally for something the size you are suggesting I'd buy a machine from a specialist manufacturer and have done with it... your size and power load is well above that you'll find in any interweb instructions.
They are highly detailed and the machine is very high performance when it comes to sucking the plastic over the tooling.
