HI. the photos does not work. please put up new links so i can see your nice project

you dont want to use a large amount of the rubber material as its quite expensive, and only suitable for really complex parts or if you are making a batch. They are really good for making small catach tanks and complex geometry, but for something like a bike frame I would use bladders or soluble cores

First time seeing this thread - great write-up, thank you for your clear explanations. Looks useful for some small components I have in mind that wouyld be tough to achieve with vac-bagging.

Hi Warren
If you guys are looking for a useful topic to make a instructional video of...making and using silicone intensifiers is something that would really help all of us. I know what they are and what they are made of and what to use them for. But I don't have practical experience or knowledge on step by step procedures. What do the rest of you guys on the forum think????
Thanks
Fred

I have done some research myself with rtv silicone, the problem is that it expands evenly in any dimension - and that means 

Scottracing, I believe the white product you are referring to is L21218 from Ami-Con (see attached data sheet).  We tried this after Amber Composites was bought out by Tencate and they no longer carry Amber's Amform 200.  The Amform 200 was much better as the Ami-Con product seems to compress more after a couple of cures in the autoclave. 

Does anyone have any sources for Amform 200, or know of any better replacements?  I may look into two-part putties (feel free to recommend any good ones), but was hoping to have a single component solution.




Thank you,

Andrew

great, thanks for the great and clear information!

Matthieu Libeert
Founder MAT2 Composites X Sports
website: www.mat2composites.com

Hi Matt,

I've create an Excel sheet that gives me the exactly thickness of prepreg. So for this project, I calculated 1.47mm BEFORE curing.

In this way you have to create the silicone mould minimum 1.5mm smaller.

Now, let's calculate how much the silicone expands with temperature:

For a 100mm silicone (this is approximately the size (width and length) of mine), for 20°C to 100°C, the silicone will expand of 1.7mm. This is your margin !

In this way, you know that you can create your mould between 1.5mm and 3.2mm smaller in width and length ! I think I had chosen 2mm.




But for the thickness (topplate), silicone will expand a little less because it's smaller. Silicone thickness is about 20mm, for 20 to 100°C, it just expands of 0.3mm. So I've created my silicone mould just 1.5mm smaller (prepreg thinkness). When I close the mould, the plate comes touch the silicone.

I hope I was clear, otherwise, don't hesitate to ask for more details !

Julien

thanks for sharing! small question, how much space did you calculated between your outer mould and inner silicone core (the place for you prepreg)