as some of you know I have my own self supporting monocoque seat and tank unit. It was always meant to allow me to make a seat and/or a tank separately but the company that took on the work originally didnt do what I had asked for so now I have had to find a way to make a fuel tank, at least, from what I have. So as I had a number of requests just for fuel tanks I made a glass fibre mock up out of my mould and just did a partial lay up and extended by a couple of inches to allow me to trim back. That seemed to work on my simple guestimated trimming so now I am making my first full carbon fuel tank. I took one of my very first monocoque units which was not up to the spec I would have liked and was going to be either used on my bike or just kept as a spare. I cut it away from the seat unit portion and made up a base. I am in the process this week of installing the base to complete the tank fully. Hope you like my work…
I started out with one of these…
I cut away the seat portion of the whole unit.
I was left with this.
I then made a tank base which again had to be modified compared to the base used for the whole unit.
Here I was checking how far I had to lay up the base to and where it needed to be made thicker as the bonding surface was going to be cut away by almost 100% in some areas so I needed to add material else where to bring back an new bonding area…
I now just have to seal and make the adhesive to bond the base into the tank… That is todays job…
It is a partial layup from this mould and the tank section is actually 4 sections plus the base which is a single piece mould.
I have been asked to just do a few fuel tanks so I have had to work out a way of doing them from a partial lay up.
I have to now… It became my sole job quite recently… :laugh:
I guess I need to learn how to make moulds soon then… :laugh:
I think the material I am using has helped a lot… This tank was a test using a part which was for me not up to spec and not acceptable for a customer. The next ones will be using the new material I have been given to try and that lets me get parts like this straight out of the mould (obviously if the mould is good enough)
awesome job! amazing finish on that.
any info you can give on the resin used and if you plan on having any issues with the reaction of race gas with it? thats one of my biggest issues i havent found much info on.
Thanks…
The tank is sealed with a resin from a UK company who make and blend resins for specific uses. This one is used in INDY car where they run E85 fuels I think. Contact Alchemie in the UK and they may be able to help…
Could you possibly explain how this fully enclosed part has strength at the seam lines?
Specifically, if this is a multi-part mold, and when the mold is joined together- you lay it up with carbon on the flanges right? and then the molds are pushed together. Then you are left with flashing that needs to be trimmed- as seen on that photo you posted at the bottom of page one.
After that flashing is trimmed- isn’t the surface area at the seam very minimal? Since you can’t really bridge the two surfaces from the backside? I could never understand this on a enclosed part either in glass or carbon.
It is quite simple. The mould has been made to overlap the tank base and create a bonding surface. With this one I had to modify the tank base slightly and add more material to make one area on each side thicker to create a wider bonding surface. ( I have cut the original seat/tank unit down to just make a fuel tank.) OK the photo with a large area of flashing is not for this tank it was an example of the surface finish I should get out of the mould using the new material I have sourced. I trim back any excess from the tank to a cut line in the mould this leaves me the extra area for bonding the base into. The same thing with the base so when I go to put the base into the tank I do have to spread it open a little to get the base to fit inside. Bonding is a little messy when you have to do this but when you clean away the adhesive that has squeezed out you know you have a fully sealed tank base and as it is a positive stop where the internal bladder pushes the base into the adhesive you also know that the base is fully home and the tank will fit the bike… I think if you over lap from the outside it is a cleaner process but you cannot be sure 100% the base has no leaks and if you have too much adhesive on the tank it could push the base down a little making it both obvious and effecting the fit onto the bike.
I guess you know how to lay up a multiple section mould were you lay up one or both sections and trim the material to the flange edge so there is no overlap into the flange then overlap material onto the section you have to attach to create the second section of the mould. You can do this in two ways one is to trim one half tight to the flange and leave the opposite side with some excess material which you do not put down onto the flange so when you bolt the sections together you can overlap that excess material onto the first section of the mould creating a join. Then add how ever many layers you want for extra strength… the other method is to cut both tight to the flange then bolt together and overlay material to overlap both cut sections and again add as much material to add strength. I choose to cut both tight to the flange because when I de-bulk I do not risk trapping material onto the flange and it stop the material moving a little down onto the mould IF I have a little bridging. For me it works a little better that way. On a single section mould I do the same but I do overlap the following layers into the flange as I use the flange in my breather stack. So a multiple section mould I still use the open flanges for my breather stack.
Here you can see both the closed flange which bolts together creating a side and top. You can also the on the side section there is a flange with locations but it is not drilled. This was one way we had planned to possibly use to help bond the base and tank together. But in the end we did not do that. So that flange is used when I make the tank to over lap material for my breather stack.
Here you can see some overlap of material onto the lower flange area but the top edge is cut close to the edge. This is to create a butt joint when it meets the tank top section mould.
Again here you can see there is no material onto the flange and it is also cut flush with the beginning of the flange.
Not quite so clear here but where the two sections have bolted together there are layers of material overlapping the joint to give strenght.
Bonding the base is harder to show…
But here is a photo from when I made one of my full monocoque seat and tank units…
I have tried a few from SHD, ACG (now Cytec)and PRF. The best one was VTF261 from ACG. Now I have a material which is not being sold yet so I cannot say what it is or where from… But this is going to be the new industry standard for out of autoclave carbon…
