Author Topic: Fibreglass and things  (Read 3523 times)

nigelhob

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Re: Fibreglass and things
« Reply #30 on: January 14, 2019, 06:15:27 PM »
hi furrari

brilliant news well done
please let me know when
i can purchase.
many thanks and once again
well done

nigelhob

Furrari

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Re: Fibreglass and things
« Reply #31 on: January 15, 2019, 12:09:48 PM »
Nigel.

Hi there.  Will do.  I’ve posted all stages of this project so everybody can see the success and failure of my learning curve.  I hope to separate all the parts of the mould later today or tomorrow.  Here’s hoping for a a success, but either way I’ll post the results.

M
Not all problems can be solved with gaffer tape.  For those there is WD40.
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Furrari

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Re: Fibreglass and things
« Reply #32 on: January 15, 2019, 03:48:44 PM »
Demoulding.  A partial success.  The mother mould and the latex mould for the face side have come off a treat.  100%.  The inside, not so good.  In fact a total disaster.  I couldn’t separate the moulds from the patern.  I’m not sure if was a mechanical lock or some other fault, but either way I’ve had to cut it off to save the pattern.
The next version/attempt will be using a part silicon mould.  This stays flexible even when cured but is very much expensive, but thankfully a lot quicker.  I’m also going to print the pouring and rising gates with a taper to reduce the chance or severity of a lock.

No pics 'cos they’re a bit boring.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Fibreglass and things
« Reply #33 on: January 16, 2019, 11:24:04 AM »
Further investigation of the problem with, what I’m calling the Mk1 mould, seems to be a mechanical lock.  Although I set the pouring gate and risers accurately at the latex stage it looks as though they’ve moved during the fibreglass stage so I won’t be using this method again.

So what am I going to do? 
I think I’ll use silicone pouring resin instead.  Much more expensive but in light of the previous failure it stands a greater chance of success.
First job is calculate how much resin I need.  Simple job, just measure the size of the pattern (the main part of the calipurr) allowing about 10mm thickness over the whole area. The SG of silicon rubber is about 1.1.  If it’s not enough the cure time will allow me to mix more but you need to allow for it when you estimate if you’ve got enough.  No FG will be required as a top, foam board being enough but you still need a pouring gate and risers.  I’m going to make these bigger (diameter) than before and out of something flexible. (Hose or nylon 11 or12).  This won’t stick to the silicon so they can be removed easily once the silicone has set so there won’t ( I hope) any problems with mechanical lock.

More after the Mk2 cast.

(Edited).   This works out at about 3.5 litres.  That’s a lot at about £18.00 a litre.

M
« Last Edit: January 16, 2019, 12:17:51 PM by Furrari »
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Darren

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Re: Fibreglass and things
« Reply #34 on: January 16, 2019, 05:55:31 PM »
this you tube channel might help with latex things, an interesting channel anyway
https://www.youtube.com/channel/UCfaq-2udXbx8BNbuzRvc5sg?pbjreload=10
D
Well, I'm into the 10th year of the project, could it be ready for Stoneleigh 2019, maybe. The longest DNA build ever

Furrari

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Re: Fibreglass and things
« Reply #35 on: January 17, 2019, 03:10:54 PM »
Silicone ordered.

I have a couple of old silicone moulds I don’t need anymore.  While you can’t recycle silicone rubber back to its constitutant material I read somewhere ( almost certainly YouTube) that you can mince it up and use it as a filler.  As this part of the casting won’t be seen on the finished job if the surface finish is not 100% it won’t matter.  I don’t have a mincer in the garage so I borrowed Management's food blender from the kitchen.  Well it does chop up (most) of the silicone to a small crumb size but what a mess it makes trying to get the finer parts of afterwards.  What I should have done was wait until the weekend when she’s out at a cat show. 
Anyway I now have about 1/2 a Kg of silicone crumb to save on material.  On with the show.

Thanks for the links Darren, I’ve watched all Smooth-On videos before but all the vids seem to cover the easy stuff and not bother with the hard, unusual jobs.
« Last Edit: January 17, 2019, 03:14:08 PM by Furrari »
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Fibreglass and things
« Reply #36 on: February 18, 2019, 11:30:52 AM »
Silicon in and poured.  Mother moulds layer up.  Upper and lower sections separated.  Packers placed on the not required flat bits. Mould release put on.  All bolted back together.

Now comes the bit I’m most concerned about.  It’s quite a big job to cast.  I’ve had problems in the past due to the PU resin setting too quick so I’ve got some slow setting PU.  This takes 7 to 8 minutes to set. 

whish me luck.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Fibreglass and things
« Reply #37 on: February 18, 2019, 05:47:52 PM »
Demoulded the casting.  Looked good but close inspection showed it’s far from perfect.  Most of is excellent but at one end there are a couple of places it’s very thin and in one area it ripped.  It’s now back in the mould to fully cure.  The problem is that the moulds have to realign within one millimetre over a distance of 400mm and it’s latex and soft silicone rubber.  I’m not going to give up on it yet.  Tomorrow I’m going to see if I can put a layer of PU and FG mat on the inside where it’s thin.  As the latex mould has survived I’ll also try FG on the inside of that, maybe with a coat of gel coat on first.

I can’t think how to align the moulds better as any packer I use will show on the surface but I suppose a PU packer might work.

Oh well put it down to experience and learn by the mistakes.  No pics as it looks just like the original did except it’s black.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Fibreglass and things
« Reply #38 on: Today at 12:14:10 PM »
So it’s on to plan C (or is it D or E) for the calipurr.

First job was to make some paper pemplates of the shape of the CF I would need.  This turned out to be pointless as once the resin is on you can’t get a big bit of CF in the space you have.
(Edited).  I forgot to say, before you cut the carbon fibre you need to give it a coat of spray adhesive that’s designed to use with CF.  This stops it fraying. ( well, more or less).

I gave the latex mould three thin coats of yellow gel coat (clear with a 10% pigment) and it’s very YELLOW.  The instructions I’ve seen say .5mm thick.  That’s easy on a large flat surface but not inside a mould 80mm side at is widest and 80mm deep.  I just did it until the latex was covered.

When the gel was at stage B (tacky but doesn’t come off on your finger) I put on the first coat of resin ( Clear but with a drop of black pigment so I could see where I had got to.). Again when this reached stage B it started to put the CF on.  At this stage I realised that I couldn’t get the templates bits on so I just cut it up.  The thickness was gradually built up.  I was aiming at 3 layers of 220 gsm.  We’ll have to see how that goes.  Finally left everything to cure. 

Checked it a couple of hours later and it it was still very soft.  The problem is one of temperature.  Should be 2-3 hours at 20 C with 18 C minimum,  the temp in the composite shop ( the back of the garage ) is nothing like that so I’ve brought it into the house to cure.  At 18C it could take 24 hours to cure.

More later.
« Last Edit: Today at 08:28:28 PM by Furrari »
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

 

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