Matt and the Easycomposites staff,

  Great write-up on the prepreg! very detailed as usual, and straight to the point. I only wish It didn't cost so much for your items to be shipped to the states! regardless of that, I'll look forward to trying my hand at prepreg in the near future. Thanks for the knowledge!

 Fred,

I'm genuinly jealous of the pressure vessel setup you built!  I'd had a similar vision in my head, but you beat me to it. well done sir.

David

Thanks for putting this together - it what I've been looking for for a while.

If you do put togther a sampler / starter kit, would it be possible to halve the min quanitites to 0.5 x 1.25m (or equivalent area) of the surface and backing ply materials.  With a small oven and a lack of suitable moulds I think getting through even the min quanties would be a struggle for me (and take up less freezer space).

Brilliant guide, especially now there are photos, keep up the good work!

Andy

Hi Fred, 

Hi Matt
I have heard that and I am very eager to try prepreg in and out of the autoclave. Is it possible to ship your special prepreg to Canada?
Fred

arren

Hi Warren
I would never use the chamber at full pressure maybe 70 psi or so. The 120psi rating gives it a good margin. I have put a new seal in it.
By the way it, is a pressure vessel not a vacuum vessel therefore it could not implode, it could only explode. I have heard of many people using these tanks for prepreg and plastic casting where you don't want any air bubbles showing in the clear castings.
I am not encouraging anyone to build one, but only showing what is possible for the right person.
Fred

   

Matt, like someone else mentioned above, when I click the link to download the guide I just get forwarded to the forum home page, there is no download which starts?

Hi Fred,

Fascinating stuff! - You're right that smaller vessels are available and if you can fit what you need to make into them then it can be more within reach (although maybe not so many people are as technically minded as yourself). When I think autoclave I tend to think of larger vessels (we have a 4m x 2m x 2m vessel, it weighs 7 tonnes!) but you're quite right that much smaller vessels are more widely available in the form of pressure pots or scientific autoclaves (often used for sterilizing).

We did have another customer who had built his own autoclave but I won't post any details of that in case I get sued.... It was not so legitimate as yours!

Still, anyone reading this article should keep in mind that the fastest growing area of prepreg is out-of-autoclave and I defy anyone to be able to tell the difference (we certainly couldn't).

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

has it been recently professionally tested??? most professional equipment used in industry be it pressurised or under vacuum has to go under regular testing during its life (as well as destructive testing of new designs by the manufacturer) to ensure it remains suitable to maintain that pressure.

You should really take it to be tested to make sure you arent going to destroy your workshop.

Its a fallacy that items under vacuum always implode safely if they fail. You can still easily get fataly dangerous shrapnel in some cases.

to be fair, as Matt says, most the smallish parts pre-preg is ideal for can be done in a kitchen oven.  Some even have a big enough and flexible seal that you could cut a hole for the silicone vacuum hose too, then just put on another seal on when the missus wants to cook dinner!!

certainly doable at home without buying second ovens or expensive custom composites ovens.

Hi Matt
Your probably right. Honey comb is a lot more advanced but I am glad you are planning it.
For those who are a bit more serious about having an Autoclave I have included some pictures of an Autoclave I have constructed for about $600.00. dollars.
I tracked down an industrial sized paint pressure pot. This one is about 30 years and is rated for 650 f temperature at 120 PSI. I had thought of making one out of pipe line pipe but quickly learned that I would probably kill or destroy my shop if it blew up. My composite supplier knew of two instances where this had happened so I decided on a certified pressure vessel. After some reading I quickly learned how dangerous compressed air chambers are.
So I found this 60 gallon tank in the USA and with shipping I got it home for about $600. (there are also 30 gallon tanks used in industry)
As you can see I mounted it on its side and made a a swing open arrangement. (The door weighs 90 pounds)
There are numerous ports to attach regulators and vacuum lines to. A bit of paint and it looks pretty good. I did price a brand new 60 gallon tank from BINKS which came to about $6000.00 dollars, way out of my range.
I then got a house hold oven and removed the eliment and heat control. I installed this inside the tank under a sheet metal tray. (not shown in pictures)
I got the tank up to 450 f which is plenty for prepreg, or cooking a turkey. The temperature and pressure is all adjustable to suit what I will be doing in the future.
I hope to connect a computer to the heating control so I can stage the times and ramp the temperatures as called for.
I am sure there are a lot of surplus tanks out there that can be found if this is really what you want to get into.
Hope this helps.
Fred