Thread: Howa Mini action - Carbon Stock Project

The alternative title "A rough bastard learns about composite materials"

Background:
I've been thinking about making a CF stock for a couple of years. Reading books on fiberglass boat building and reading technical manuals on carbon fibre filled in many hours in the evening.

12 months ago I made a fibreglass stock from a plug of my own design, inspired by the good work of @Robojaz

For want of a better option I went about trying to fit it onto a JW15. That was a disaster, ended up heavier than the factory wooden stock with loads of pock marks and voids. They say you learn from mistakes so I must have learnt lots.

-----------------------------

The Howa Mini.
The factory stock has been described as a "fat heifer of a thing"
Like a few others have done I took to it with power tools and edited the shape.

Factory shape


Chop chop



Not being a savage from Southland, I glued the factory foreend back on.

Then went about making a mould. Cut the shape out of your parting board (melamine in this case, it was free)
Plug up all the edges with modelling clay. Doing this takes about 2 hours more then you would expect.

After reshaping








The wee pyramids are so the second half of the mould has something to locate onto.



Then the plug and parting board get waxed up to help prevent being glued together.
Cover the thing with a tooling gelcoat. The gelcoat I got came in a lovely shade of red.




Any abrupt edges I filled with a thickened resin. This is because fibreglass really hates going around sharp corners. I wanted the edges to be as neat and defined as possible.




When that's got to a nice tacky stage the layup of chopped strand mat could commence!
I only used about 4 layers of chopped mat in total. Lots of poking with the brush to get things together nice and firm. At this point I'm not worried at all about weight so used plenty of resin. From experience having a resin rich coat on top makes it much nicer to handle the mould without getting jabbed by any tiny bits of glass poking out.



Do one side, leave for 24hrs, pull the parting board off, apply another 6 coats of mould wax, tooling gelcoat, thickened resin, more chopped strand mat.
By this point you realise making mould's sucks. You also know it's the most important step really. Any fcuk ups here are really hard to fix later on...
Eventually you end up with a stock encased in fibreglass.