Having a go at making a head mould so I can covert some fins. The pic shows what I have done so far. I am using my most in-spec fin as a plug. Can anyone see any problems with it? Given that Powerbox has so much taper I dont think there will be too much trouble withdrawing the fin as long as it is well waxed. Or am I standing into danger? Opinions please!
(Please excuse the crude nature of this prototype)
What will the fill inside the MDF box be?
Anyway, yes well waxed and it will rip out easy
If you do silicone around a head and then a two part mother mould over that it will never ever stick.
If you work quick, a tube of normal Bunnings silicone, lots cornflour and 10-15ml water will set up wonderfully and not cost $80 like the two part stuff
Love what your doing , even that I don't know what your doing .
Is it a US to Power box that your doing ?
Looks like a power to Tuttle on closer zoom.
If so ,
A resin , chopped glass mash will work great.
Got to get the brass nuts kinda close , + or - a couple mm or so.
If it's a little loose paint a layer of resin on both sides and with a flat file , file it in.
Love your engineering prowess ! 
PS , looks like u know what your doing , if u got 2 part resin mixing skills that's great and the best . If not , I'm a great fan of Araldyte full strength , ( Bunnings easy ) with glass fibre ( any kind chopped up with scissors ) mix to fix any windsurf issue . It's expensive but easy 
I should have said the mould will be made of epoxy resin poured in around the plug.
Plug of what ? What are u doing ?
Breath !
When u say mould do u mean the casting mould for future jobs or the mould (filling ) that your doing ?
Select to expand quoteSparky said..
So you aren't using fish sauce?
U naughty boy , and yes I'm pickled
Did you do a JSA before you started ?
I think Crusoe could help you out if you didn't.
Select to expand quoteImax1 said..
Plug of what ? What are u doing ?
Breath !
When u say mould do u mean the casting mould for future jobs or the mould (filling ) that your doing ?
Making a mould so I can cast new heads on old fins. The fin in there now is acting as the "plug" - the original shape that the mould will provide exact copies of. It will be well waxed and then I will pour resin into the box, surrounding the plug. When the resin is cured, pull the plug out and hey presto you have a head mould.
Select to expand quoteSparky said..
So you aren't using fish sauce?
That would be just silly! Sheesh...
Go for it .
dont just pour it , rather stuff it with a glass resin mix with an icy pole sick .
Plain resin is weak and fragile .
At least mix old chopped t shirt , coconut husk , chicken wire , cat , the whisky stuff that gets cought around your whipper sniper head .
Select to expand quoteMark _australia said..
What will the fill inside the MDF box be?
Anyway, yes well waxed and it will rip out easy
If you do silicone around a head and then a two part mother mould over that it will never ever stick.
If you work quick, a tube of normal Bunnings silicone, lots cornflour and 10-15ml water will set up wonderfully and not cost $80 like the two part stuff
That sounds interesting but I don't understand it.
Are you talking about a stiff outer mould (maybe fibreglass) that supports a soft silicone mould lining the hole?
What do you do with the cornflower and water?
Select to expand quoteShifu said..
I should have said the mould will be made of epoxy resin poured in around the plug.
That's a big slug of epoxy. Maybe slow cure hardner is in order, particularly as it's in an insulating box.
We have a problem Huston ,
As far as I can see we have 2 scenarios .
I ca n see a awesome jig ( auto spell is doing my head in )
Im not sure of the qqustion ,
Stiffu baby are u wanting to make a awesome mould or are u wanting to mould ?
Heat is a friend , that's what it does .
What your doing is your friend .
Perfect with what your doing.
ps.....as long as it's no thicker than 5 mm
The only problem is when u mix heat with ****y styrene foam that can't handle the truth .
In my old days with spare resin and Mekp , just for ****s an giggles ,for young person ****s , n , giggles , after they said cracker night was bad , it cought fire , I **** u not .
Select to expand quoteNotWal said..Shifu said..
I should have said the mould will be made of epoxy resin poured in around the plug.
That's a big slug of epoxy. Maybe slow cure hardner is in order, particularly as it's in an insulating box.
The slug your talking about will be no problem , in fact it will be perfect , reinforced or not.
Reinforce it!
Select to expand quoteNotWal said..Mark _australia said..
What will the fill inside the MDF box be?
Anyway, yes well waxed and it will rip out easy
If you do silicone around a head and then a two part mother mould over that it will never ever stick.
If you work quick, a tube of normal Bunnings silicone, lots cornflour and 10-15ml water will set up wonderfully and not cost $80 like the two part stuff
That sounds interesting but I don't understand it.
Are you talking about a stiff outer mould (maybe fibreglass) that supports a soft silicone mould lining the hole?
What do you do with the cornflower and water?
Yes
Mix silicone and flour, add water and mix well. A squirt of food colouring also works and you get nice coloured putty and that way are assured it is mixed properly. It will set faster and tougher than just normal silicone sealant. Its a bit if an art as it goes off fast and so only works for small moulds. But it works GREAT
Mother mould is then fibreglass over the silicone so it does not move when casting. Or, auto bog over silicone and slap some 6mm MDF on, whatever.
Then, to free stuff up one can remove the mother mould, then flex the silicone to remove the part.
