Slow Monster rebuild

350TSS · 11-12-2018, 07:22 PM

Today was a day that started very badly but ended up sort of OK.
I started by trying to separate the split mould from the pattern for the Ignitech enclosure. Fortunately. I remembered to drill the flange between the two halves of the mould so that it would register in the same place when I come to put the Carbon fibre and epoxy resin in, 4 x 6mm holes about 50mm apart. I then trimmed the borders with a dremel (using a c40mm diamond disc cutter) so I had a thin line between two coats of black gel coat on each half of the mould to aim at with the wood chisel. Horrendous quantities of evil dust were generated and even with a top quality mask I could taste it on my tongue.
The first setback was that the pattern separated from the base. For this I blame Gorilla glue which is in my humble opinion not a patch on Evo stik exterior wood glue (blue container). Then, although I had a distinct line to aim at with the chisel, the two halves just would not separate. My only option at this point was to chisel out the wooden pattern, which was made from marine ply covered in filler and hard gloss resin. Marine ply is made with the grain on each laminate at right angles to the one below it. Wood chisels are not great at cutting across grain. The wood was coming out in thin strands looking like pulled pork but with considerably more effort required.

Two hours later some of the pattern was still inside the mould and worse the filler had de-laminated from the wooden pattern and was proving very stubborn to remove.

In all honesty, I think the pattern was too intricate and whilst I did my best to shape it so there were no parallel sides I do not think I entirely succeeded and consequently the release agent on the pattern was not slippery enough to overcome the extent of mechanical locking caused by the shape and intricate details. Eventually I got it all out and there are about 4 or 5 places that will require repair where the chisel clashed with the gel coat.
Three lessons learned here, 1) use a really strong glue to attach the base to the pattern and if necessary mechanically fix with screws; 2) do not skimp on the width of the margin for the mould separator (min 50mm I had less than 25mm for the Ignitech enclosure) you cannot lay the fibre glass accurately to the edge of the margin so you will have to cut the margin back after all the fibre glass for the mould has hardened off; and 3)ensure that the gel coat is as thick across the whole width of the separator margin as on the main body of the pattern. The reason my mould would not separate was because the gel goat was less than 100% and the voids were replaced with the polyester resin applied with the first and /or second coats used to reinforce the mould. The release agent works exceptionally well on a smooth gel coat surface but substantially less well on a corrugated gel coat surface and almost not at all when the corrugated gel coat is contaminated with polyester resin.

11-12-2018, 07:22 PM	#11
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	Today was a day that started very badly but ended up sort of OK. I started by trying to separate the split mould from the pattern for the Ignitech enclosure. Fortunately. I remembered to drill the flange between the two halves of the mould so that it would register in the same place when I come to put the Carbon fibre and epoxy resin in, 4 x 6mm holes about 50mm apart. I then trimmed the borders with a dremel (using a c40mm diamond disc cutter) so I had a thin line between two coats of black gel coat on each half of the mould to aim at with the wood chisel. Horrendous quantities of evil dust were generated and even with a top quality mask I could taste it on my tongue. The first setback was that the pattern separated from the base. For this I blame Gorilla glue which is in my humble opinion not a patch on Evo stik exterior wood glue (blue container). Then, although I had a distinct line to aim at with the chisel, the two halves just would not separate. My only option at this point was to chisel out the wooden pattern, which was made from marine ply covered in filler and hard gloss resin. Marine ply is made with the grain on each laminate at right angles to the one below it. Wood chisels are not great at cutting across grain. The wood was coming out in thin strands looking like pulled pork but with considerably more effort required. Two hours later some of the pattern was still inside the mould and worse the filler had de-laminated from the wooden pattern and was proving very stubborn to remove. In all honesty, I think the pattern was too intricate and whilst I did my best to shape it so there were no parallel sides I do not think I entirely succeeded and consequently the release agent on the pattern was not slippery enough to overcome the extent of mechanical locking caused by the shape and intricate details. Eventually I got it all out and there are about 4 or 5 places that will require repair where the chisel clashed with the gel coat. Three lessons learned here, 1) use a really strong glue to attach the base to the pattern and if necessary mechanically fix with screws; 2) do not skimp on the width of the margin for the mould separator (min 50mm I had less than 25mm for the Ignitech enclosure) you cannot lay the fibre glass accurately to the edge of the margin so you will have to cut the margin back after all the fibre glass for the mould has hardened off; and 3)ensure that the gel coat is as thick across the whole width of the separator margin as on the main body of the pattern. The reason my mould would not separate was because the gel goat was less than 100% and the voids were replaced with the polyester resin applied with the first and /or second coats used to reinforce the mould. The release agent works exceptionally well on a smooth gel coat surface but substantially less well on a corrugated gel coat surface and almost not at all when the corrugated gel coat is contaminated with polyester resin.