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350TSS · 02-07-2019, 09:08 PM

Today I cut my cross ways baffles and after positioning them with duct tape on one side I CF’d them into place. Tomorrow when the first side has cured the other side will also be CF’d.
Next I moved onto the tank top. After almost a success with the seat base I was hoping that I had cracked this CF malarkey.
The first dent to my over confidence came after I had mixed up the epoxy (260ml) and applied it to the gel coat already in the mould. In about 3 or 4 places it crinkled the gel coat, which means that these places will end up having to be filled from the outside.
I cut my cotton pattern some while ago and went to cut the CF which I intended to use as the first lamination, which I was hoping I could lay down in one sheet with just a few minor cuts to accommodate the shape of the mould. The remnant on my roll was not quite big enough so I broke out my second roll and the CF, whilst the same grade, weight and weave as the original roll, was considerably stiffer than the first roll material. It was as though it had been starched. Within about 20 minutes it became clear that there was no way this second batch was not going to be laid down in one lamination with minor adjusting cuts. In the end I had to put it down in seven overlapping sections.
Because of the overlapping I needed more resin than I mixed so the last panel went in with the last dregs of resin on the brush rather than being saturated then rolled and squeezed with a scraper with the surplus being recovered for use elsewhere. I read somewhere it is not a good idea to mix two batches of resin mix in one lamination, so there was a lot of begging Peter to pay Paul.
The next problem was that the tank top mould when inverted is about 400mm deep with near vertical sides and the epoxy resin, which is very thin has not the adhesive strength to hold the CF at the top of the mould, gravity overcomes the adhesion and the CF separates from the top of the mould and starts to migrate towards the centre bottom of the mould.
After a good hour of buggering about I had all the CF wet, all the sides right up to the top attached and everything hunky dory so I retired for a well-earned cuppa. I deliberately used slow cure hardener when I discovered that the second batch of CF was nowhere near as pliable as the first. It will take at least 24 hours to go off fully as mixed.
I came back about an hour later and the sides had separated from the mould and worse there were bubbles on both sides at the transition between the very top of the tank and the sides. It is very clear that in wet laying CF the CF mat moves as the resin cures, it tends to move to its woven flat state pulling it away from the desired/required mould shape. The proper way to make CF is with resin pre-impregnated mat with a vacuum bag drawing the catalyst through the resin whilst the mat is held tight against the mould by the vacuum bag. The resin with the CF anchored in the right place cures in the bag either with assistance of an oven or over an appropriate time.
I spent another hour or so with the roller trying to stretch the CF mat within the setting resin and re- securing the sides to the mould. I have a feeling this will not end well, I have no intention of staying up all night prodding the increasingly resistant resin into places the CF mat does not want it to sit.
My real concern is that I decided on a CF tank for lightness, at each step in the manufacture the weight has gone up. Were 3 laminations sufficient for the base? The easy decision to take was to add another 2. The base is now extraordinarily stiff, as stiff as if it was pressed out of 2mm steel.
Fixing my faux pas with filler is kind of essential cosmetically but does nothing for the overall objective. A lot of filler has been included, a lot has been rubbed off. I guess it will be next week before I find out if I have saved the planned 3kg, what do I do if it is only 1kg - start again?

02-07-2019, 09:08 PM	#954
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	Today I cut my cross ways baffles and after positioning them with duct tape on one side I CF’d them into place. Tomorrow when the first side has cured the other side will also be CF’d. Next I moved onto the tank top. After almost a success with the seat base I was hoping that I had cracked this CF malarkey. The first dent to my over confidence came after I had mixed up the epoxy (260ml) and applied it to the gel coat already in the mould. In about 3 or 4 places it crinkled the gel coat, which means that these places will end up having to be filled from the outside. I cut my cotton pattern some while ago and went to cut the CF which I intended to use as the first lamination, which I was hoping I could lay down in one sheet with just a few minor cuts to accommodate the shape of the mould. The remnant on my roll was not quite big enough so I broke out my second roll and the CF, whilst the same grade, weight and weave as the original roll, was considerably stiffer than the first roll material. It was as though it had been starched. Within about 20 minutes it became clear that there was no way this second batch was not going to be laid down in one lamination with minor adjusting cuts. In the end I had to put it down in seven overlapping sections. Because of the overlapping I needed more resin than I mixed so the last panel went in with the last dregs of resin on the brush rather than being saturated then rolled and squeezed with a scraper with the surplus being recovered for use elsewhere. I read somewhere it is not a good idea to mix two batches of resin mix in one lamination, so there was a lot of begging Peter to pay Paul. The next problem was that the tank top mould when inverted is about 400mm deep with near vertical sides and the epoxy resin, which is very thin has not the adhesive strength to hold the CF at the top of the mould, gravity overcomes the adhesion and the CF separates from the top of the mould and starts to migrate towards the centre bottom of the mould. After a good hour of buggering about I had all the CF wet, all the sides right up to the top attached and everything hunky dory so I retired for a well-earned cuppa. I deliberately used slow cure hardener when I discovered that the second batch of CF was nowhere near as pliable as the first. It will take at least 24 hours to go off fully as mixed. I came back about an hour later and the sides had separated from the mould and worse there were bubbles on both sides at the transition between the very top of the tank and the sides. It is very clear that in wet laying CF the CF mat moves as the resin cures, it tends to move to its woven flat state pulling it away from the desired/required mould shape. The proper way to make CF is with resin pre-impregnated mat with a vacuum bag drawing the catalyst through the resin whilst the mat is held tight against the mould by the vacuum bag. The resin with the CF anchored in the right place cures in the bag either with assistance of an oven or over an appropriate time. I spent another hour or so with the roller trying to stretch the CF mat within the setting resin and re- securing the sides to the mould. I have a feeling this will not end well, I have no intention of staying up all night prodding the increasingly resistant resin into places the CF mat does not want it to sit. My real concern is that I decided on a CF tank for lightness, at each step in the manufacture the weight has gone up. Were 3 laminations sufficient for the base? The easy decision to take was to add another 2. The base is now extraordinarily stiff, as stiff as if it was pressed out of 2mm steel. Fixing my faux pas with filler is kind of essential cosmetically but does nothing for the overall objective. A lot of filler has been included, a lot has been rubbed off. I guess it will be next week before I find out if I have saved the planned 3kg, what do I do if it is only 1kg - start again?