Hi Fred,

Why does a silicone mould have to be under high pressure ? Obviously the higher the better, squeezes out resin etc. But to get a flat surface on both sites could i not just clamp a silicone mould. Does silicone stick to curing polyester resin ?

Update: Well Ive made the mould now. Was very annoying as I broke the plug taking it out. It has made me question the radius so I think i will be getting some epoxy filler.



Next step is buying the supplies.

Is there anyway to determine the theoretical thickness of each cloth layer, once its been wetted ?  

Hi Jack
Does that sound wrong some how? Funny!
Your mold came out real nice. Just a thought. Bladder molding and silicon expanding cores give off a lot of pressure so your mold would have to be very strong, just keep that in mind. The only molding of that type that I have seen were two matched metal molds.
Others on this site can probably add more information and advice to help you along.
Fred
 

Update: Back to work now so can work on the mould. Using the easycomposites mould starter kit wax and pva release worked well.



I have now sanded the flanges back a bit. Next step is to make a mould off the other side.

I have decided  to attempt bladder moulding. So am looking into making a male silicon plug moulding, once the next part of the mould is done.

• Any recommendations for a 2 part silicon product I can use ? I intend to heat the curing part so the silicon expands etc.
• The layup will be fibreglass weave for now, bit cheaper. I have been thinking 3 layers: 100g twill tweave sandwiched by a heavier weave. This because I have sharp angles and the part isnt structurally too important. Are there any calculations to find thickness of layup ?

I need to know layup thickness now because I have to take that into account for the 2nd part of the 2 part mould.

Thanks in advance

Well the mould making kit provided just enough putty for the job. Pretty happy with the result:

Got it  

I have the same problem in making a fuel tank. The join needs reinforcement but there is no "open" end to add fibre tape to the join on the inside.  I don't want to hijack this thread but I guess it's the same issue.  This is the tank in plastic.

the answer is to make one side of the mould with flange... then put a 3-6mm (depending on intended part thickness) layer of wax over the flange (your step diagram 2) and take the other side of the mould.

quite a few solvants will dissolve plasticine so just wipe over the plug to clean it.

Its a bit late now but you could have used sign board to do the flanges easier than the plasticine, then just use plasticine for the joins/curves.

Anyway could you please draw a diagram, or show photos of it ? bit puzzled by your wording

you make the 2 molds.