Super 7 Mirrors


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scottracing
scottracing
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I've been looking to make a few bits for my mates sevens, but with work and not having the correct materials to hand its taken until now.

After the issues I had with my first mould (my mistake due to part undercuts) I borrowed my friends machined ali mould, it needed a good bit of prepping as it still had a lot machining marks due to the depth of cuts, but after a 400grit wet and dry start all the way up to metal polish, this was the end result.

http://www.talkcomposites.com/Uploads/Images/deda9019-2250-4671-bc5e-c76d.jpg




I tried getting the tool into my laboratory oven and it will fit but is very tight, and i would still need to run the vac lines and make sure the bag isn't damaged, so I took the chance on trying a bit of wet lay but using a vac bag to give better consolidation and get a bit of the resin out of the laminate.

I have a background in laminating, but with prepregs in the aerospace and Motorsport business. I had forgotten how much I hate wet lay, its messy, the fabric doesn't stay in place and its just generally a nuisance, especially with a short pot life of 40mins with the resin Sad

The resin was starting to go off as i was laying the last ply, I used a 240gsm 2x2 Twill for plies 1 and 3 and 310gsm NCF ±45° to bulk it up, the NCF doesn't drape into such deep pockets very well so i had to dart it and cut into stripes, but here's a photo of it all in the vac bag.

http://www.talkcomposites.com/Uploads/Images/6d838794-a3a2-4af2-a9f1-6afd.jpg


And what was the result you ask? Well I didn't use as much release film as I should have as I was trying to save it, so some of the breather caught to the resin but no big issue.

http://www.talkcomposites.com/Uploads/Images/98e42241-b726-4597-b09c-303f.jpg

http://www.talkcomposites.com/Uploads/Images/af74f522-46a5-4df4-8ffe-633b.jpg


There were a couple of dry spots and a few pinholes, but the parts are for a race car so I will just give them a quick flood coat of 2k lacquer.

I was thinking of laying the dry fabric plies on some released glass or release film and impregnating them with resin before laminating them into the tool? Would this be a better way of doing it? as trying to wet out the plies in the tool was a real pain even though I used loads of resin and stippled them with a brush.

http://www.talkcomposites.com/Uploads/Images/102f5693-b6e1-4e1f-87fc-b15a.jpg


After a bit of trimming and sanding the parts looked good, I cant recommenced the perma grit tools enough!! the little disc cutter on a dremel was awesome and the sanding blocks make short work of sanding back to the trim lines, wish I had a set of them a few years ago!

For a first quick shot using wet lay and a vac bag, using non-perf release and heavy breather the results aren't bad, the surface finish is of course good as its a polished ali tool. But I need to address the dry spots in the first ply.

Any recommendations on what you would do, and yes I know infusion is the next way or cut the tool in half so I can use prepregs Smile

http://www.talkcomposites.com/Uploads/Images/b11b25f8-272a-46ee-8030-3af0.jpg
f1rob
f1rob
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Hi mate nice job,did you get my pm the other week re work/Bristol ? Was messaging someone the other day and cant see the message I sent you in any of my folders ?

re the mirrors any wet lay I do I cut a square of material big enough to cut all my templates out,lay that on a sheet of plastic,pour my resin on and use a squeegee or filler spreader to move the resin around and wet out the cloth

Another sheet of plastic on top then you can mark your template shape out on the plastic an cut out with scissors

LOT easier than wetting out individual templates

Also sometimes you can get better results with a bleed on the job rather than pulling full vac

P.S you can do that in preepreg !!!

Use one of your wetlay mirrors as a former,heat an drape your prepreg over it,quick 10 minute chill in the freezer then pop it off an drop it in the Ali
VVS
VVS
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Ive found infusion pretty easy and clean but wet lay and vac seems a bit hit and miss, definitely got best results with only a light vac.

If the fast hardener is going off too quickly mix it off with the slow to get an ideal cure time.
scottracing
scottracing
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hi rob, i didn't get the PM send us another one? I need to update you on the other 'thing' too Smile

I carried out another layup yesterday to the procees what rob said, apart from I used a piece of released glass and put the material on it and whetted it out with a squeegee. Then cut it out with my lovely new shears (thankfully a nice tin of acetone to clean them at hand). 

Its currently sat in the bag and I will see how it comes out this time, I cut the NCF material into strips for easier draping into the tool. So hopefully they shouldn't be as heavy and the twill should look a bit better. I'm using non-perf release film, but I might try out some peel ply on the next one to soak up some of the excess (if any). I will also look at giving it a light vac rather than pulling full vac.

Yep some EC prepreg will be bought and used on my own tools when i remake them, I need to give this ali tool back to my friend next month before I move back to the UK.
Edited 9 Years Ago by scottracing
scottracing
scottracing
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Well after a couple more attempts wetting out the plies with the resin, I'm getting better results although not perfect as theirs still a couple of dry areas and loads of pinholes, nothing a bit of wet sanding and lacquer cant fix, but as these are for race use they dot need to be perfect only light Smile

So ive got 3 plies in the laminate, 2 plies of 240gsm 2x2 twill and a reinforcing ply of 310gsm NCF ±45°

Going to make some tools from the latest parts using the EC epoxy mould paste, as I have to give the metal tool back in 2 weeks Sad





http://www.talkcomposites.com/Uploads/Images/876369b2-0fb3-4f95-93ec-dfb7.jpg
http://www.talkcomposites.com/Uploads/Images/fdf387e5-34c1-4ce9-b358-596f.jpg
scottracing
scottracing
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Had a trial with this red and black twill, the fabric was a lot less pliable and needed a lot of darts cut into it to get it to drape into the tool. I need to repair a couple of dry spots again so definitely need to sort the process out a bit.

http://www.talkcomposites.com/Uploads/Images/2c6a8a8a-e4ae-47c4-8de7-36e6.jpg
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