With the season approaching inexorably I had a careful read of the new regs last week.
As I sort of half remembered there is a specific change concerning holes in the bodywork. This means that my hole
in the bonnet, for the air filters-as shown here, is no longer legal. To be precise it would be OK if it was sealed
to just around the air filter but it seems a sensible approach to look at a bonnet scoop anyway. At some point
making some sort of airbox would be a good idea and getting a bit of practice in with GRPing would be a good idea.
So, the first thing do was to work out what to do. I had spent a while looking around for some sort of suitable domestic device that I could turn into a mould but that had been rather fruitless. Hence it seems that I'm going to have to make a mould which is not something that I've done very often before.
After some thought it seemed that a foam based mould would be a good idea so I set about making a device
into which to pour the nefarious foam liquid. i covered a large amount of the bonnet in packing tape, which has
the secondary effect of net sticking too well to things like polyurethane foam, and then made this curious cardboard
box construction.
I then mixed up a small quantity of foam and poured it in and then shoved it around a little as it started to foam up.
After a while I took the cardboard off and ended up with this. This is still pretty firmly
stuck to the bonnet although I have a theory that it'll come off moderately easily once I start pushing hard.
I spent a while hacking around at this a cake knife that I liberated from the kitchen. What's more I also reconstructed a bit of the mould and added some more foam to the left hand side of the device.
I eventually ended up with this, which I reckon is just about the size and shape that I
want. I'm slightly concerned that it might obstruct my vision a bit but I'll have to put the car on the ground
to check that. As well as being cut to shape this lump was sanded to make it mostly smooth and I also added some
bits of plasticene around the edges and in some of the larger voids that had appeared in the foam. I don't think
it's the best starting place in the world but it should do for now.
What I now need to do is to make this thing impervious to polyester resin. (Or, get some epoxy resin from somewhere.) I can then take a mould from it that I can then use to make the real thing in. The current plan is that once I've got something that is just about this shape then I can bond this to the bonnet using yet more glass matting.
A long term plan is to seal this to the filters underneath to get a sort of air-box-like effect. (It's not really the right sort of shape but not too silly.) However that can wait for a while. I could even make a new mould for that, Mark II, device.
Well, my entry for the new RGB series came back and I'm in with the same number
as last year. Logic says I ought to change it to 51 but that would just be too depressing. In fact, thinking about
it the entry pack actually arrived on my birthday. Oddly we've got "2005 registered competitor" stickers
this season. Heaven knows what they're for.
So, back to the mould making. I had realised that I didn't have anything like enough gelcoat in stock so ordered some more from CFS which came today. So, this evening things started off with putting some gelcoat on the buck. I had previously (yesterday) covered this with packing tape, mould release wax and PVA release agent. With luck at least something has to give way...
Problem was, it was rather cold in the garage and although I realised this I still stuck to the regulation 2% hardener and it took ages to go off.
While it was doing that I bodged around the Palm wiring so that the palm could get connected to the power supply I made for it. However, on connecting it it didn't notice that the power supply was there. I suspect this is because it's putting out about 3.8V rather than the 4.1V that the Palm charger does. I may change it or I may just leave this, as 3.8V is probably still enough to drive it.
Once the gelcoat had gone off the required amount I started slopping resin about and put a layer of
glass tissue and two layers of CSM (chopped strand matt) on top of the mould's gelcoat.
This time I put 3% hardener into it so it wasn't such a wait. However, I found out half way through that my consolidating roller had got all gummed up and I wasn't able to do as good a job as I would have liked of getting the air bubbles out from under the matting. I hope it won't affect the stability of the mould itself.
All the same, I'm a bit unsure about whether this scoop is too large. If I've got enough resin and so on, I'll probably finish this mould and, assuming that I don't screw up, I'll change the size of the buck and take another mould, smaller, mould off it so as to have two approaches. Clever, aren't I?
At long last I separated the mould from th buck and trimmed it up. It's not wonderfully
high quality but I think it will do. I actually used some filler to clean up the worse of the imperfections in
the mould until it looked like this photo. This is actually what it looked like after I'd rubbed away wet-and-dry
for ages, to the extent that I ended up with my fingertips bleeding and it was starting to go all red so I had
to stop for a while.
After recuperating for a while (although it's still pretty uncomfortable) I put some release
wax and some PVA release agent into the mould and made the scoop that you see here... The point, of course,
is to cut off the flange around the bottom and, ultimately, to bond it into the bonnet itself. I know that it isn't
really the right sort of yellow but it will have to do for now.
This isn't perfect but it would nonetheless be functional. One problem, though, is that I got my calculations wrong and put in much too little catalyst in the gelcoat. This seems to have resulted in the gelcoat being soft (or perhaps it's a result of too much pigment?). Whatever, I shall now make another one, which is the advantage of going through this business of making a mould of course, with rather more hardener in it. Also, I could do with making the gelcoat a bit thicker so as to give a bit more leeway for flatting it all down afterwards. However, that'll have to be tomorrow.
I'm a bit late updating this site, as things have moved on a bit. First of all, I've put some wheels back on the car and put it back on the ground. This seems like quite a big step as I can envisage actually driving it again. In fact, I got in and drove it forwards about 50mm. This is the first time that the car's moved under it's own steam since the engine blowup at Mallory which was back in October.
In the last few days I've made another bonnet scoop from the same mould. This one was rather
more successful than the last although still a very long way from being perfect. However, I can at least imagine
bonding this one to the car. What I'll probably do is to get yet more gelcoat and pigment (I'll try a different
colour this time) and spend a long time trying to get the mould into better condition than it's in at the moment.
Then I can make another one.
However, if the worst comes to the worst the current scoop is easily usable.
I didn't actually do anything today, but the increasing proximity of the season and the need to do at least some testing is making me think about what needs doing. Hence, I updated the to-do and to-get lists with the current situation. Unfortunately, there's an alarming quantity of stuff there.
