38 replies to this topic

[TUF 308]

Been a fibreglasser for about 4 years now thought it about time i use my skills to make some moulds for a bonnet for my car. im aiming for around 9kg, will have inner and outer skins.

started today progress so far




Flanges glued onto bonnet flush with top for outer skin mould.




Gelcoat sprayed for mould

Also got the first layer of glass on mould this arvy hopefully finish top mould tommorow then start on inner skin mould on weekend. More pics to come

[lakeside]

how many kilos in a steel bonnet?

[Bart]

id love to do this myself, could you explain how its done in more detail?
Thanks mate

[rodomo]

Some good info here:

http://www.atomicmpc...s=2&c=18&t=1971

[GML-31]

hes only on the start of it.... will need a lot of bracing on it to stop it distorting, helped make a lot of molds 20 odd years ago for car kits

[TUF 308]

Finished Top mould today. Applied more layers this morning then put ribs on this arvy, so top is all finished. will flip tommorow and start on inner skin mould.

Today:


final layers of glass put on.


Started to lay out the ribs. Using lowdensity foam which is cheap and easy to sand.


Hot Glued on then corners are sanded smooth.



2 layers of 450csm (choppy) applied over ribs. Top mould done apart from trimming.

how many kilos in a steel bonnet?

dont have a exact figure yet but i think around 16kilos

[Heath]

Yeah I would have estimated about 15kg because they aren't overly heavy. This 9kg bonnet seems kinda heavy to me... I would have hoped for 6-7kg... maybe I was being a bit optimistic. But keep up the good work

[TUF 308]

Whoo, finished inner skin mould today. Start making a bonnet monday after a little bit of trimming of the inner mould.

Today


fliped over with flanges ripped off and trimmed up.


all taped up ready for gelcoating


spraying pva which is a release agent so the gelcoat does not bond to the bonnet


gelcoated


tie layer, which is a fine layer of 225csm which wraps around corners better than heavier glass so as not to get air voids. air voids leads to the gelcoat cracking out first time you make a part.


All done. 4 layers of 450csm done 2 at a time so it dosen't heat up to much

Yeah I would have estimated about 15kg because they aren't overly heavy. This 9kg bonnet seems kinda heavy to me... I would have hoped for 6-7kg... maybe I was being a bit optimistic. But keep up the good work

looking at it today i think 9 kg might be over estimated. if i dont gelcoat the bonnet i think i could easily make 6-7kg. if money wasnt a issue i would use carbon fibre but at $90 a sq. meter i think ill leave it.

[TUF 308]

Yeah mate spraying or even brushing gel coat on before you glass will eliminate the pitting. gel coat coat will give a much better mould surface than glass. gelcoat will also be a easier surface to work with you can just hit it with some wet and dry and give it a buff and it will come up half decent.

Edited by TUF 308, 05 January 2008 - 09:05 PM.

[TUF 308]

Looks like we where a bit out with the weight of a standard bonnet, weighted it today

I weighed 97.5 kg and when I picked up the bonnet it said 119kg, so thats 21.5 kg.

Very close Lxchev i got 22kg. so yeah heaveir than the 16kg i thought.

Progress today

Demoulded in the morning


outter skin mould came up great


all trimed up, also came up good


inner skin glassed


also did top skin didnt get a photo. will be gluing together on friday trimmed up saturday ready to be weighted

[Bart]

Carbon fiber next?

[Heath]

Baronvonrort, what exactly is "Nomex"? Is that that kind of honeycombe style core that they use in 'sandwitch' construction kinda Carbon Fibre?

[TUF 308]

Bigmac123_99 Posted on Jan 7 2008, 06:32 PM
� will you be considering orders cheaper then the other available supliers?? i am after a bonnet but i cant justify spending $450 yet.�

Possibly mate wanna see how the first one comes out and have a bit of a play around with weights keep you updated.

(Bart @ Jan 7 2008, 06:11 PM)
Carbon fiber next?

all of what Baronvonrort said applies. I am kinda limited to what i can do as the moulds could not withstand the baking that prepreg reqiuers. Normal carbon fibre would be ok with vinly ester resin but its just the price of the stuff its so bloody expensive. But my next move maybe a sandwich core, vac bagged which is one of the reasons why i extended the flanges. I have alot of things i can play around with its just finiding the time to do it. I am looking forward to friday + sat when its all finished.

Edited by TUF 308, 08 January 2008 - 06:07 PM.

[TUF 308]

Glued together today



pop it out morrow, trim up, tap holes, done yay

[Tiny]

Bloody excellent job is all i can say!

Thanks for the pictures too, this should really be in the tech section!

[TUF 308]

Tiny Posted on Jan 11 2008, 06:51 PM
  Bloody excellent job is all i can say!

Thanks mate

adrianj Posted on Jan 11 2008, 09:10 PM
  u make me one?

hehe, i wanna make sure there good before i start makin em for other people get a few wrinkles ironed out.

Well its is finished i was so exicted this morning when i poped it out, it was so light trimmed it up then weighted it. 7kg it came in at which i am really happy with. its so easy to lift by myself, just have to be careful when the wind picks up as the bloody thing takes off a little. haven't had a chance to fit it to my car yet, am going to take springs off the hinges and maybe fit a gas strut anyone done this?

anyway pics





all up i spent about four 7 hour days makin the mould, and 3 days makin the part.

[makka]

Looking Good!

it wouldnt be too hard to do a CF one, and you wouldnt need a brace on the inside, you could just run a layer of sandwich 50mm wide under the edges and a sandwich cross from corner to corner. for the canopies/farings we used to make we used vinylester resin to keep the costs down but for the spaceframes we used epoxy.

Did I mention I used to make Carbon-Kevlar tubing, that was good fun!

Edited by makka, 12 January 2008 - 06:40 PM.

[Tiny]

How does it go for stiffness compared to the steel bonnet?

Also do you know if it's legal to use a glass bonnet on the street? It's bloody good an an easy weight saving! The way youve done the bracing i think it would be hard to tell!