Vac Tables: What do you cook your plastic with?

[stormtrooperguy]

I'm looking to finally build my own table, and I'm waffling on the heating element.

The rig I've been borrowing is based on an electric oven. It works fine, but I'd like something more efficient (I spend from 4 - 10 minutes per sheet heating right now).

I've been reading up on nichrome coil heaters, and the debate over hardibacker as a safe material to use for the shell.

I've also seen people gut electric griddles and such and assemble them into an array of heating elements.

One of the big things I notice is that most of the hardibacker/nichrome style heaters are very short... the walls are only about 4.5" tall. For some of the pieces I pull, I have to let the plastic droop a lot... 5" or more (0.125 HIPS, pulling over an object about 10" tall). So, I'd have to build much taller walls to accommodate that.


For those of you that do this at home: what are you using? How well does it work?

 

[Thermalized Plastics]

I'm looking to finally build my own table, and I'm waffling on the heating element.

The rig I've been borrowing is based on an electric oven. It works fine, but I'd like something more efficient (I spend from 4 - 10 minutes per sheet heating right now).

I've been reading up on nichrome coil heaters, and the debate over hardibacker as a safe material to use for the shell.

I've also seen people gut electric griddles and such and assemble them into an array of heating elements.

One of the big things I notice is that most of the hardibacker/nichrome style heaters are very short... the walls are only about 4.5" tall. For some of the pieces I pull, I have to let the plastic droop a lot... 5" or more (0.125 HIPS, pulling over an object about 10" tall). So, I'd have to build much taller walls to accommodate that.


For those of you that do this at home: what are you using? How well does it work?

I like to use Ceramic Heaters.:love There very stable for heating up plastics of all types.
　
　
thermal:lol

 

[pandatrooper]

Any links to good ceramic heaters to use for this purpose? The ones I've looked at are all really small (unless you're combining small ones grouped together?)

 

[Lee S]

I used an electric BBQ turned upside down and mounted above the vac table. Was cheap and simple, but did the job.

L

 

[Smeeon]

I've seen a table made from sheet metal that was heated from a garage style gas heater below. What made it work nicely was it evenly heated the plastic without burning it and keeping a constantly hot surface, this was used for duplicating car parts like fenders etc. but I'm sure the concept could be applied. Unless your talking applying heat from above the object as it lays on your vac table with the plastic on top of it.
the method I'm talking about was very Frankenstein but.. isn't all of this? hehe

 

[clonesix]

I think ceramic heaters are best, but expensive for the hobbyist. The guy that sells the Proto-form plans sells heater kits that seem reasonable priced.

www.tk560.com has a lot of vac/heater info

 

[jonjohn29]

I think ceramic heaters are best, but expensive for the hobbyist. The guy that sells the Proto-form plans sells heater kits that seem reasonable priced.

www.tk560.com has a lot of vac/heater info

i made my own table but got a used oven to heat the plastic up.

 

[Lunchbox]

Here's my semi annual "come out of lurking post"
I used the plans from a wonderful but slightly dated book called The Prop Builder's Molding and Casting Handbook by Thurston James runs about $25-30. It has an entire chapter that outlines building a Vac-Table from frame, to pump plumbing, and most important, wiring the Nichrome open coil oven. ( Looks like a big toaster oven )
Pre-coiled Nichrome elements and creamic suspension posts can be purchased through http://www.infraredheaters.com/thermo.htm
They sell a large variety of heating products, but most of the plastics related items are a bit pricey and aimed at industrial use.
Other than the Vac pumps, my biggest expense were the creamic posts.
My table is a blast, I can't imagine hobby life without it, if you're thinking about building one I personally recomend picking up the book and pulling the trigger. Hope that helps a bit.
P.S. I pull large / deep (up to 10 in deep) armor / helmets etc... using up to .125 HIPS without a sagging problem.

 

[tubachris85x]

ugh...building the oven was probably the most stressful thing I've ever built. Didn't heat too even, but at least it worked....

Parent's weren't too thrilled when I fired the thing up, cause I blew the circuit. Later on, I just made the electric bill skyrocket. Hey, I was only 16 at the time :lol

 

[stormtrooperguy]

I think ceramic heaters are best, but expensive for the hobbyist. The guy that sells the Proto-form plans sells heater kits that seem reasonable priced.

www.tk560.com has a lot of vac/heater info

I've been reading there... I tried to register, but no luck on activation so far, and it's been a few weeks.

I was all set to go the coil / hardibacker route, but I have some questions about the amount of power needed, making a taller oven, etc...

So, if anyone involved in the site is ready, help a nerd out and activate me please! (username stormtrooperguy)

 

[tubachris85x]

I've been reading there... I tried to register, but no luck on activation so far, and it's been a few weeks.

I was all set to go the coil / hardibacker route, but I have some questions about the amount of power needed, making a taller oven, etc...

So, if anyone involved in the site is ready, help a nerd out and activate me please! (username stormtrooperguy)

I'll PM jim, I'm sure I'm still a moderator over there...haven't been on in awhile though :angel

 

[stormtrooperguy]

thanks!

i've got a few ideas about the hardibacker issues that have come up, and want to bounce them off people.

i did all the electrical work in my house, yet i'm intimidated about making an oven. *shakes head*

 

[tictoc]

I am very interested in this thread as well. I have James' book but I had the same sort of electrical concerns.

 

[stormtrooperguy]

I'm very tempted by the protoform heater kit... $226 doesn't seem bad for a well designed, relatively safe oven.

I've sent off an email to them. Anyone have personal experience with this kit?

 

[pandatrooper]

TK7602, please let me know if you get a response back. I was probably going to ask him the same questions you have.

I've been working on my vaccuum platform, and Protoform's heater might do the trick (and save me some time) for the heating side of my table.

Thanks!

 

[stormtrooperguy]

i emailed the protoform guy and got a reply pretty quickly. i'm about 99% sure i'm going to go this route... it will cost more, but it seems worth it.

mmm, time to learn to weld. how exciting

 

[tictoc]

Is the $226.00 just for the heating element(s)? or is this thing assembled? I thought you still needed to buy the plans for $75.00 and then spend $1100.00 in materials to build the machine. I must be missing something.

 

[stormtrooperguy]

Is the $226.00 just for the heating element(s)? or is this thing assembled? I thought you still needed to buy the plans for $75.00 and then spend $1100.00 in materials to build the machine. I must be missing something.

that's just the heating element. that's the only part that i'm nervous about on my own... i'm pretty handy, but i don't know the resistance/temperature/power/etc... stuff for things like that well enough to wing it.

the whole thing will probably be around $1000 or so... a lot of the supplies i already have on hand. i know i won't need to buy any wood!

 

[Knowone251]

I used an electric BBQ turned upside down and mounted above the vac table. Was cheap and simple, but did the job.

L

My friend used the same method but with 2 electric BBQ's that he got at wallmart. He made a simple housing out of aluminum to mount them above the table. I believe the workable table space is 18inx24in but i could be wrong. Its a decent size for hobby work and the BBQ's were between $30 to $40 each.

 

[stormtrooperguy]

I'll PM jim, I'm sure I'm still a moderator over there...haven't been on in awhile though :angel

Any word on that. I'd love to actually get on there!