Mould Build

General Composites Discussions Composites Talk
#1

Following another discussion about mould flanges in which I posted some pics of what I was doing and Canyon asked if I would post a whole new thread detailing what I was upto with this mould.

Its a multi part mould for a 1970’s formula one car nose cone.

Ill start with a bit of background… A customer of mine came to me with a mould at the start of the year for a car that he had just taken over looking after, well this mould was ready for the scrap bin, since then I have made 5 pieces from this ‘scrap’ mould! trouble is because the mould was in such a bad state there was a lot of finishing to do on the panels that were coming out. I said to my customer that I would try and get one out then use that to make a usable mould from (he needed one to go onto the car in a hurry).

Then this nose got wrecked, so I salvaged a second out of the mould under the understanding that I would make a new mould from that right after the next race meeting… Surprise same thin happened again and it got wrecked, this happened 5 times in total !

So now the car isnt going to be racing again this year so got one last piece out the ‘scrap’ mould and turned it into my pattern.

So now I will show my progress on making this new mould,

Its not a rush job but more of a fill in type job between when im less busy.

IMG_3744 by dobsonm, on Flickr
This is the flanges being attached

IMG_3756 by dobsonm, on Flickr
Showing the support frame under the flanges

IMG_3766 by dobsonm, on Flickr
They are then edged filled with plastercine and shaped using wire type clay tools

IMG_3768 by dobsonm, on Flickr
Flanges completed and ready for waxing, Notice the interlocks to ensure that the lower section in the mould will line up prefectly when it is split apart.

#2

IMG_3769 by dobsonm, on Flickr
Given 7 Coats of wax and then sprayed with PVA release

#3

Polyester tooling gelcoat was then applied and left to dry (sorry I forgot to take a pic at this stage)

Then one layer of 300gsm (1 once) chopped strand mat was then applied with regular general purpose polyester resin. Choppies were added in the tight corners and around the interlocks.

This can be seen in the pics below.

IMG_3778 by dobsonm, on Flickr

IMG_3779 by dobsonm, on Flickr

IMG_3785 by dobsonm, on Flickr
This is once the first layer of CSM has cured (about 10 hours since it was layed

#4

Matvd,
top-notch plug there!
I looked at you company website “4d” in the gallery pic’s it looks like a blue “Tiga” in there. I really like the S2000’s I’ve done quite a bit of work on them.
Here is one that I crewed on years ago and made a lot of (bits) parts,& upgrades. I have almost a complete set of molds for the DB-2 and nose molds for Tiga’s

#5

Yes that is a blue Tiga on my website, I did a bunch of tubs a few years back. I used to run a DB2 a few years ago and built a couple of carbirs (I know brian utt) when I worked for the company that were European agents for carbir. I really like the sports2000’s but over here there just isnt much of a market for them as its nearly all hobbyest owner drivers that like to tinker with there cars and not spend much money developing there cars. shame

Im actually aware of that car your with, I was trying to convince someone over here to buy it about two years ago!

PS thankyou for your comment about the plug, It took quite a bit of work to make it decent.

#6

This is then rubbed down to ‘de-nib’ (remove any spiky bits). I just used a 60 grit DA disc by hand to do this, it only needs a very light rub.

IMG_3792 by dobsonm, on Flickr

If you see any air bubbles in the laminate they should be rubbed out at this point.

IMG_3794 by dobsonm, on Flickr
This shows the whole area ‘de-nibed’, after this it is then wiped down with acetone to clean the surface and get it ready for the next stage.

#7

awesome write up!!

#8

Thanks, Im trying to be detailed as I can without making it too boring!

#9

Awesome pictures! To composites enthusiasts the more details the better!

#10

IMG_3798 by dobsonm, on Flickr
I then cut the CSM for the bulking layers, these were 1 x 300g, 3x 450g and 2x600g csm, these were all cut and places to one side in order of laying up.

I mixed the resin in 2kg batches, used a 3" brush to apply and then roller to consolidate. It is important to keep the roller used regually after each layer to ensure that no areas are left to gel with air voids.

The resin that I used for this is a ‘tooling’ polyester resin that has low shrinkage and with a post cure can be used as elevated temperatures. This resin requires that all these layers are laminated in one session as the thinkness is needed to create an exotherm that the resin needs to cure correctly.

IMG_3801 by dobsonm, on Flickr
I started by laying up all the flange areas first, starting at the back and working my way around, all layers were laminated one after the other before moving to the larger centre pieces.

IMG_3813 by dobsonm, on Flickr
All layers laminated on this section, this now need to be left to fully cure before the next sections can be started.

#11

no please, the more detail the better!! :slight_smile:
we all have a common intrest but we all work differently so it really helps to have explanations sometimes

…tooling resin? ive only ever used normal poly resin for my moulds [and epoxy sometimes] … is it much pricier than normal resin? many more benefits?
i understand the tooling gelcoat, and obviously what tooling is for, but i havent really heard much of tooling resin?

#12

Thank you for this thread! I would like to order the materials to build my first mold this weekend and this thread couldn’t have came at a better time. :slight_smile: Do you have to use CSM or can you use a woven glass like plain weave? I thought I read that a woven fabric would give a print threw which would affect the surface finish of the mold.

Edit: Also do you have to use PVA or will just wax work? I have had nothing but horrifying experiences with pva trying too get a good surface finish on flat sheets.

#13

You could use woven cloths for your mould but there wouldnt be any real advantage to it, infact it would be harder to do because it would be easier and more likely to get air voids. It would also cost more as CSM is about 1/4 the price of a woven glass cloth.

You dont have to use PVA, wax is usually sufficiant, I have used PVA on this one because I wanted to guanentee that I didnt pull any of the paint off the plug because I will need to do further laying up on it once the main pieces are done to enable me to have joggles flanges for joining the top and bottom pieces of this body item together.

#14

What are you making?

#15

Fuselages for R/C heli’s, swim platforms for a boat, some other marine parts like interior and engine accs., and what ever else I can get my hands on for practice.

#16

Here is what I mean for fuselage or as we like to call em canopys.

#17

Why ordinary polyester for the skin coat? If you are using stuff which is capable for elevated temperatures, I would make the skincoat from a high temp resin as well. also, what happened to that skin coat? Is it just the photo or are patches of laminate white?

Choice of tooling resin is good, but indeed, getting it all together before it gels is a tough job at times.

#18

A regular polyester for the first ply because it allows you to get the first layer on making sure that there is no air in it. A tooling resin wont cure proporly if only one ply thick. Also the manufactures data sheet recomends using a regular resin for the first ply.

The white patches are just where the laminate is thicker due to overlaps. Some are areas whers there is three or four layers due to the overlaps. Only small areas tho.

#19

its better to tear the mat rather than cut it so that it will blend with other pieces, this will help build thickness equally.

#20

Yes most of it does have torn edges. There are only small areas where there is a thicker build up. I wasnt worried about this, it was more important at this stage just to get a layer on the whole piece.