Building a single fibreglass fin for a spoon

loftusm · January 2, 2012, 3:47am

Started with a wooden template that was drawn in Corel to get the dimensions right. 10" height x 6 1/4" base. It should end up about 3/8" thick at the base. I’m going for a fairly thin and flexible fin. It won’t be hard to replace if it breaks.

In an attempt to conserve resources I kept the fin layup box fairly compact.

The first 22 layers of 4oz are now under pressure. It worked a treat. Great Compression.

I put a layer of aluminium foil on both sides of the glass and put the wooden template fin on top and clamped the whole layup box to the bench.

I used laminating resin for these layers.

Once the clamps were removed I peeled of the foil and was left with an excellent impression of the fin.

This is what the bottom looked like when I took it out of the mould.

The outline was cut with a jig saw, about 1/4" away from the final shape and ground down the rest on the linisher.

Revealing the hidden potential of the fin. My Dad’s linisher was the perfect solution. I did put my dust extractor hose under the belt to suck up all the dust.

The first 22 lams after shaping.

To build the fin I used all the corner offcuts from the board to save and reuse valuable materials. They were the perfect size.

Using a more compact layup box helped to save on resin too.

I’m adding another 5 full lams, with laminating resin, to each side of the fin, giving a total so far of 32 lams.

This is the last step to glassing the fin. Adding the smaller foils to each side of the 32 lams to give a total of 42.

There are 2 patches, of diminishing sizes, for each side of the fin.

I used brown paper to cut the sizes and then pin the glass to the brown paper to cut them.

This is a good job to do while watching television. Just make sure you’ve got the vacuum cleaner (hoover) handy.

Once again, I used the offcuts from the board glassing to make all these pieces. I will use a hot coat to apply these foils to make it easier to sand.

Now I will sand and foil the fin to the right flexibility for me. Will post images when done.

yaar43 · January 2, 2012, 5:47am

Hey Loftusum,

I’m curious, how thick was your final product? Did 22 sheets of 4oz under your clamp down set up come out thinner than 3/8".

Steve

loftusm · January 2, 2012, 9:32am

Hi Steve

Yes, the 22 sheets ended up about 1/8".

I have since added 5 more sheets either side and it is now about 2/8". Next time I’ll start with 30 sheets then start the foiling.

I will soon start layering 5 more sheets, both sides (a total of 10), progressively up the fin to create foil.

It should be pretty close by then. I have attached an image of the foiling.

regards Muchie

yaar43 · January 2, 2012, 5:55pm

I have done 38, 40, 42, and 44. I know 42 and 44 sounds like a lot but they work great for foiling and I glass those on. Im still just trying to figure out how I can create a router tool so I can just push the fin base through so it will come out perfect to fit in the box. I have a hell of a time with the bases.

One of my 2012 resolutions is to not make or foil another fin until I get my dust extraction system set up. All I need is some more money. Maybe that should havebeen my resolution, get more money to build more stuff.

Steve

astevens · January 2, 2012, 4:19pm

NIce work. I can’t remember where I heard it (probably here) but one sheet of laminated 6oz is about .01 inch. 3/8" = .38" so you would need about 38layers of 6oz for 3/8" thickness

loftusm · January 3, 2012, 12:27pm

Hi Steve

thanks for the input. I think you’re right. About 40 layers is going to be spot on.

Do you have an image of your fin base with some measurements? I may be able to help.

Dust extractor: I must agree. I couldn’t live without my dust extractor, especially as I do woodturning and woodwork too. It is invaluable.

Max