So I am doing my first real pre-preg tool.  The mould I had made for me has had issues........ loads of stress cracks appeared after only a couple of pulls.. Not looking for answers or reasons why that mould has had issues. I got so pissed off that I looked into a dozen different things and all I got was dizzy with each person giving me a different reason.  So I took one I had made and lacquered it to get a good finish and to remove some of the raised areas where the original stickers got left on the tank when it was moulded.  I put it back into the mould and have started to remake the mould using pre-preg carbon tooling. So far it seems to be working.. I have done the top section already and although I have not removed the section from the part the flange areas look perfect and if the rest of the mould comes out the same way I will be happy. Having had numerous quotes to remake the mould for me including a quote from the person who made it in the first place (he seems to feel it is other reasons and not his work that has caused the problem). I have bit the bullet with some Tooling from SHD. 

I will post updates as I go and hopefully in a few days will have a finished working full carbon pre-preg mould. 

What layup you doing as it doesn't look like a 1-8-1 ?

what's the thinking behind the peel ply/glass cloth ?

Different places have their own ways but mostly everyone puts 20mm wide strip of 200g cut +-45 on all female corners

After debulk on 1st ply bootlace all female corners with 2/3 strands of 650 cloth

would also cut your first couple of 0-90 plies into the tight corners

Don't really need location features on the flanges as its a lot stiffer than Grp most people just use drill bushes from Talbot tools moulded in where you bolt the mould together

Just using a 1-4-1 lay up as recommended by SHD. If they recommended anything specific I would have done it.. I have cut the first ply tight into the corners though. worry about bridging and it not getting all the way down so I cut into the corner to be sure. 

The locations my not be needed for carbon but the mould I am remaking was glass so it is a case of make one section at a time and remove a section of the old mould as I work from section to section.. 

1-4-1 is very lightweight 1-8-1 is industry standard 20 plus years

only ever going up I.e 1-10 or 1-12

lot of places don't bother with the last 200g on a 1-8-1 the thinking being on a fairly complicated mould the variation in thickness/overlaps its going to have more Than a 200g differance so its not worth trying to balance it

that and the fact a single ply off 200 isn't going to affect multiple plies of 650

people who sell you a matched 1-8-1 system will never tell you that thou !

DONT cut the 1st ply into the corners ! Not if you want a mould to last.

If you don't 45 strip in the corners do what they do at Williams and take your 1st part of the ply into the corner and 5mm onto the other face.

then when you do the other face butt that into the corner.

DONT cut the 1st ply into the corners ! Not if you want a mould to last.

If you don't 45 strip in the corners do what they do at Williams and take your 1st part of the ply into the corner and 5mm onto the other face.

then when you do the other face butt that into the corner.

DONT cut the 1st ply into the corners ! Not if you want a mould to last.

If you don't 45 strip in the corners do what they do at Williams and take your 1st part of the ply into the corner and 5mm onto the other face.

then when you do the other face butt that into the corner.

I did cut into the corner then overlay from the flange up onto the part face about 5mm to 8mm as didnt want to just rely on the backing layer. As this is the first pre-preg mould I have had to make I have only done what I was told would be a sure way to get the material to work and to be honest once I have made the next 5 tanks from the mould I have no idea how many more I will make from it.... I dont see it being hundreds... lol..

Cheers.. It is thin but it is what they recommended and I agree the last 200 gram layer is not going to do much with a 1-8-1 lay up. The glass on the surface layer is to help get the air off the material and I guess help the resin flow. I did try a previous version on some flat sheet to see how it worked but there was some glass visible on the surface when it cured. The new material has not had the same issue with the moulds I have seen so far. The previous version worked perfectly in an autoclave but not so well as an oven cure. This has been developed as an oven cure tooling and looks to be working very well on all of the moulds I have seen and what I have seen so far on the flange faces. 

SHD,s owners all come from ACG (now cytec)all the many data sheets they produced over the last 20/25 years had various versions of putting glass toes in at various points to help it de gas, No one ever did it thou as it never made any difference !

Be interesting to see if this does do anything ?

Do you have any dealings with Paul Russell at SHD ?

Only rep I know at a composite firm who has actually been there at the coal face and done the job and knows what they are talking about

All the others are just good salesmen who will show you a fantastic flat sample taken off flat glass sheet

Or very good "theoretical" chemists who will tell you how it "should" work