The Shop > Composites & Plastics
Glass fibre mould from the slender plug
PekkaNF:
Thank you Steve,
You always give me usefull information to go with.
I pated down onto gelcoat twill woven fabric 160 - 200 g/m2, that's what I had in hand ant it looks like that samed my day. No problem's on the mould part of the most laborous and ambitious mould on the mould part, but all the trouble in the world outside of the mould area,
I had then impression that the mat is used to make moulds with polyester to build the bulk, it's cheap and it's available. I never really have been using much mat to epoxy, because the bulkier ones are for polyester resin ( I think it's the emulsion binder on the mat that does not work well with epoxy).
So far I have been opening three moulds, I haven't opened the last one I laminated. I'm having some trouble I am not certain, which was my inexperience in laminating, which was wrong choice of materials and was there incompapibility issues.
I made four moulds and one came out fine, one bombed (not sure am I going to try to fix it or do parts from plywood instead), most difficult one and the one I had all the trouble with came out usable on important features, but outside of those it has all the problems I can think off (did not burn though....) and the least important mould I made last and I'm willing to write off before I even open it is not open yet.
I'll make some post, one mould at the time. Comment welcome,
PekkaNF:
This is sword #3, katana size fantasy sword that is higly impractila in any material. I had a comics drawingis to go, so I break o pieces that can be made.
The plug was easy to make and this is the first mould I made last night, Black gelcoat (used for the next item from the same pot). When gelcoat was coldilocs tacky, I patted precut pieces of twill woven fabrics, stiipled resin with brush and added a layer of mat, rolled it down and then final layer of twill. Pretty thin mould but I need only one piece out of it.
It did work out fine, has few air inclusions and few plug under runs. Nothing too severe thoug.
The last picture of the blade tip is about 1" wide, kept the shape pretty good. Mould is washed but not sanded or finished.
PekkaNF:
And this is sword #2 handle that I laminated in stages (used leftovers to smaller parts).
It is rather deep and large mould. This is the mould I had most trouble with in every step on the way.
Used the gelcoat from the same batch that previous one, this is the first time the gelcoat started to gel in the mixing mug and when it happened I rejected the rest and made new batch.
I covered the critical parts of this mould with the pieces of twill woven glass cloth, patted them down and proceed with mat, which I run out of and used leftover fabrics, because I had no idea how to pause at this stage: a) leave the gelcoat to dry 6-8 hours and continue as nothing happened b) put one layer of cloth/mat, laminate it with resin and then wait 6-8 hours before shops opens. Option b is tricky, because I have not been able to get toolin/laminating polyester resin, it is all finishing resin (wax in it, has to be ground off to continue).
Anyway, I had all the trouble during lamination: gelcoat that starts to set, resin that does not wet mat well, deep structures that I had hell of the time trying to press down and remove air. It was getting dark too and my worklight was a streetlight 50 meters away.
Next time I will not rush things.
But those wrinkles on the flat part of the panel. What I did wrong?
Ugly, huh?
vtsteam:
Okay, I see, you're using mat to bulk up the female mold after first laying on cloth.
As a suggestion, it would be easiest then if the mat is laid in as narrow strips of reinforcing after your first layers of cloth -- maybe three of the mat strips -- two for the two edges to reinforce the mold flanges and a narrow one down the center to reinforce the bottom of the mold. These three don't have to touch. In fact it would be harder to get them in place and saturated if they did. The thing you want to avoid is trying to bridge an inside corner with any mat strip. It just won't want to stay there easily, or without bubbles.
There will be spaces between the separate strips. That's okay. As long as the flange strips come in all the way to the edge of the sword without turning 90 degrees onto the blade. After the mat is in, you could lay in your backing cloth or more mat or whatever. From that point out, voids don't matter much, you are just building thickness and stiffness in the mold.
The handle area will be different -- I'd be tempted to just build that up as cloth only. It will be hard to make mat lay down there.
I'd still use 45 degree cut cloth strips to do the layers against the gel coat, to get the best conformity without air bubbles or voids. Actually I'd use it throughout -- even the final reinforcement over the mat. It just lays down so much easier.
PekkaNF:
What did I do wrong here? Parts are about 2" wide and longest part is 5"? long.
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