Balsa Mouldie build version 2

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Well heck it's been a long time, and with my new promotion will be again so I'll fit this in over the next couple a days or so.
So you want to build a mouldie, just getsome glass ,carbon, a shape ,resin , mix with an egghead and throw in the garage, hey presto a mouldie, NO I DON'T THINK SO.

As it would appear the quality of the result is in direct relation to what you know how good your plug is and how suitable your work area is. This might be obvious and you might be thinking no kidding sherlock, but it's part of the learning curve.

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so if your bench looks like this don't expect a good result :'

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So the first thing to do is make a plugg, some use pine block and seal it(like to much hard work but durable) .Some use foam, just dont' drop the stuff or put iton some sharp pointy glue on your not so clean work bench.
Mine I made out of balsa covered with cloth, then got excited and covered with carbon on the premis(hahaha) i might make an actuall fuse out of my plugg. coulda shoulda probably woulda.
So this is what my plug and seperation plate/thingy.
Again with the seperation plate/thingy if you use a good material a better result. Scabbing some old building site junk probably wasn't a heck of a plane, thought it would work.
The result is your initial half of the mould is not so good and the the second half amplifies the errors.
[img src="[/img]img18.imageshack.us/img18/7787/dscf1160edited.th.jpg"]

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so this is my plugg for my mould and my seperation plate/thingy
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so once you have a plugg, a seperation plate/thingy, cut a hole in it to fit your plug and seal it with modelling plasticine.This will inevitably(??) lead to getting a load of this stuff on the side of the plugg, which I found you could get off by using the wax that you used to put six layers+++ on the plugg. It also appeared that since you need to wax the seperation plate/thingy, you may as well wax the side of the plugg your going to mould, again*6.
Then just for good measure I used some PVA stuff to aid the seperation from the Plate/thingy.(oops dinner I'll be back)

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PVA, great idea and of course you can never use to much, or can you.Well what I did after sealing the plugg in the seperation plate and rewaxing it, I slapped a load of PVA on top. What appears to happen is that it dries out to a thin layer( depending on how thick you put it on), the layer peals off when you take the plugg out, in theory.
If you put to much on when you put the gel coat over the plug and seperate it there will be a gap between the plug and gelcoat, wierd but true.but let me back up a bit.
So the plugg is ready, cover in gelcoat, one layer is probably not enough because depending on the products you use the resin eats the gel coat and you get worms/wrinkles etc. Soo to prevent this put one layer of gel coat on, when it begins to set, best when almost set allowing the layer covering the plug to be almost set, place a layer of glass cloth tissue( actually I used a giant chucks cloth which worked, it's just a barrier to stop the resin eating the gel).Then put your second layer of gelcoat.
I used a fairly hot/quick set of gel, then when the second layer of gel was almost set I did a cover of 225 matt( think that's what it was called) with a slow/cool set of resin.It was tacky enough to get the matt cloth tostick to the gel. Once that was set I did another layer of glass matt(heavier at 425( been up since 3 so can't actually remember wot its called)).Resined and left to set.
End result is half a mould.
Since I put to much PVA of simply errored when I took the mould and plug off the plate there was a 3-4 mill gap around the edge of the mould heck who knows why, so I had to redo it and it looked like this.

[thevon]

Keep it comin' Dickon, it's very interesting! There's a few of us gonna be trying this soon, so any experience/ tips are gratefully received!
Andrew

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Seem to be having a problem uploading the pics, will give it another go, but otherwise willl have to wait till tomorrow as I have to get up for work at 4am

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When you've done one side and got it out of the seperation plate/thingy being careful not to cause the plug to fall out of the first half of the mould, this keeps it tight with no gaps to cause problems for the second half. Also an error can be caused here, if you think your completed section of the mould is set, be careful,I took mine off and and although it felt dry and set,somewhere b/w the gel and outter side of the matt wasn't, so when it did set instead of being flat there was a slight curve in the edges of the mould, so m suggestion is to leave it a good 24 hours before seperating from the plate/thingy or from each other.
Remember when the second half is done to ensure te plug on that side is clean,I waxed mine up again and was about to create the 2nd half when I realised I hadn't waxed the gel coat on the first half(DONT FORGET).Used PVA again, very vey skinny usage tis time,used a clot to apply, but you could spray or use a brush.
Seperating the two sides wasn't to difficult I used a steel rule to loosen it up all round and the prised one half off, no prob. Now it's stuck in the other half without any grip potential topul it out, so flex as best you can without damaging the mould to loosen the plugg,if you did a good jod with wax and PVA it will come out ok, eventually. Apparently most pluggs are lost in this process, but mine was ok,just needed to knock off a bit of gelo, which is good cos I want to use it tomake a mould for the canopy and maybe even as a plane it's self.

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Mark out your canopy, and cut it out, oh yes so easy to say, don't use a hack saw, use somthing with power(little electric jig saw), resin , 2 layers of cloth and gel is quite tough to cut, I used a little hand held saw I cut the canopy area out with and the tail section.
I then attached the slightly curved half of the mould to a frame work I created, it served 2 purposes, one to take the curve out and the other to have a steady work surface to join the two halfs together after the lay up.
Which when you've done all this that's the next stage.
OH yes more waxing (6*+++) on the inside of the moulds, then more PVA release ointment, again very skinny.
If your really dedicated you could sand(wet n dry) the inside of the moulds with 1000/1200/and greater to get a really good finish,my first attemptso didn't bother, just cos I didn't know.
Allfor now more tomorrow.

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PS for today, when you make the first half use some kind of keying technique to align the two halfs, otherwise it'll never match, which is crucial of course. a mate of mine (who makes models large ones, for the movies) made me some round half cone shaped things which I used, which if you look at in the pics you might notice on the moulds and seperation plate/ thingy, for ever now known as the P/T.

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hey Andrew. Kinda got carried away last night. excitment and all

[thevon]

Haha, no, that's great. Should be more of it.

It would be good if your pics came up properly and you could view them in the post. Have you read this:

windsock.proboards.com/index.cgi?board=forumadvice&action=display&thread=285

I think you need to host a full size version of the pic somewhere, then view it in your browser and paste the URL into the post, and then highlight the URL and click on the image icon to put the code around it.

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So the next thing I did was to get prepared for the lay up.How good your mould is will depend on how good the end result is, of course.I was a bit worried about the resin eating gel issue, so my movie mould maker mate gave me some of his gelcoat. This prevented the problem, but because I had use a lesser gel on the mould a few small bits got pulled off.so use a good gel coat from a boat yard or similar for the mould and the modell your making.

Ha figured it out at last. ;D ;D
This is how the gel in the mould looked.
As you have two sides fitting together you dont want any gel slopping over the edge of the model bit onto the flat joining bits.Obvious really, but not quite so easy if you want to get the gel right to the edge, I had to use a cloth to wipe some surplus gel off, but hey there you go.