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decrepit said..
I like the 21.5, looks very similar to my PB fin a 19.5 45deg

mike Stuart's a cheeky buggar

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keef said..

decrepit said..
I like the 21.5, looks very similar to my PB fin a 19.5 45deg

mike Stuart's a cheeky buggar

Keef, that looks virginal, haven't you used it yet?

I'll post pics tomorrow of my latest experiment, end grain balsa, stainless steel, carbon hybrid.
The end grain balsa is a real pain to shape, it's density varies immensely, I'm going to try end grain palm next.
I purchased some 50mm x 5mm stainless bar, so I can try my idea of setting the carbon in a rebate in the steel, so the carbon is full thickness all the way across the chord, until it butts up against the leading edge wall. It's a lot of work to shape the stainless, but I think if you don't have to rebog the fin after every big session it'll be worth it!

Under no circumstances have I infringed on any copyright!

Painting your fins now?

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dweller said..
Under no circumstances have I infringed on any copyright!

Painting your fins now?

great looking fins Stuart and simular to the fin Mike sent me ( in the pic above ) , I have just returned from LG and there is no weed this year with small chop, the water is very murky so it's hard to determine where the shallow water is (so you need a short fin )
the 21.5 would be great for LG with the nice wide profile but not enough rake for lake wollumboola ,

Mike I have used your fin a few times with my 6.2 until I noticed some wear on the leading edge and exposing the timber so I didn't want to damage it any further,
what I found is it tracked to windward extremely well and feels nice and solid , I have showmen your fin to Stuart at Primbee

looking forward to see your end grain balsa and the stainless project, I remember all of the negative comments about my fin's until those guy's started wearing out there $250 mxr's ect

Pity about exposing the timber, I thought I'd put a 5mm resin/microfibre bog leading edge in front of the timber. May be worth doing if I haven't.

OK here's the process, the stainless is a 5mm by 50mm bar, so I can get 3 pieces out of the width.

I'm copying the upper fin, so the stainless is getting shaped to it's leading edge, with a rebate approx 5mm back, I won't part it from the parent bar until I finish shaping,
that way it's easier to clamp.
It's resting on the end grain balsa and stiched bi directional glass I'll use to join two thickness of balsa together. Without the centre glass layer, the balsa would fall apart in the thin places. The centre line also helps with shaping.



So here is the stainless bonded to the balsa, with the rebate edge raised above the fin body, the stainless layers butt up against this ridge.



And here's the carbon on the first side, lot of work to do yet, but it's coming on.

looking good mike, it looks similar the the small fin I sent you , I hope your going to do a step by step thread on this fin , I imagine its not easy keeping everything strait ,HOW DID YOU DO THE RESCESS ,
I was having trouble with twist in the stainless with the heat from the drill and hacksaw, eventually the mold sorted it out with compression

I like the idea of the balsa it would act as a shock absorber when hitting solid objects

I tried using a milling machine tool in the router to do the recess at first. But I think the router spins too fast, I couldn't keep the tool cool enough to stop it softening and going blunt.
So I tried my 4" right angle grinder. I found a 1mm thick disk is ideal for cutting the stainless, and with care can be used to create the edge of the recess. Then with equal care I used a 5mm thick disk to grind the rest of the recess out. It doesn't look a precision job, but the carbon hides all that.

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keef said..
looking good mike, it looks similar the the small fin I sent you , I hope your going to do a step by step thread on this fin , I imagine its not easy keeping everything strait ,HOW DID YOU DO THE RESCESS ,
I was having trouble with twist in the stainless with the heat from the drill and hacksaw, eventually the mold sorted it out with compression

I like the idea of the balsa it would act as a shock absorber when hitting solid objects

Used your small fin today, went really well, in my 43 with a 5.4koncept, wind didn't get as good as I expected, so no great speeds, but everything felt nicely balanced.

OK here's the next step as requested. The powerbox that Basil needs this fin for, is shallower than the tuttles I make, so there's going to be more pressure on the top and bottom of the box. Although endgrain balsa is supposed to be very good in compression, I want to make sure, also I don't want any water getting anywhere near the timber.
So I've removed the balsa around the edges of the head and up into the fin where the nut and bolt go, and will replace with an epoxy/micro fibre mix. This should seal the wood and greatly improve compression strength.

Well finally it's almost finished, just needs the barrel nut fitted.



Next job is to make a stainless leading edge for my 18cm assy.

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decrepit said..

keef said..
looking good mike, it looks similar the the small fin I sent you , I hope your going to do a step by step thread on this fin , I imagine its not easy keeping everything strait ,HOW DID YOU DO THE RESCESS ,
I was having trouble with twist in the stainless with the heat from the drill and hacksaw, eventually the mold sorted it out with compression

I like the idea of the balsa it would act as a shock absorber when hitting solid objects

Used your small fin today, went really well, in my 43 with a 5.4koncept, wind didn't get as good as I expected, so no great speeds, but everything felt nicely balanced

mike i just noticed your post , craig cole pointed out today that Conan's best NM was on that fin at almost 32knts with a 36.8 2sec gpsteamchallenge.com.au/sailor_session/show?date=2013-10-17&team=5

gary warren bolted it into his board at primbee and said it had to much lift and opted for a 22 mxr , and the down fall was to sail in more chop

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decrepit said..
Well finally it's almost finished, just needs the barrel nut fitted.



Next job is to make a stainless leading edge for my 18cm assy.

looks great, whats the go with the power box looks light for the stainless

im thinking about doing a molld with 1/3 of the base flexithane 85, with the comptesion the consistancy between a soft rubber and a break shoe peddle , if you lay the stainless into a mold with carbon and there is an overload , i'm hopeing the flexithane will oborb the extra pressure with out cracing the mold , what do you think

edit :" read your post and found its Bazils fin , you never seiese to amaze me , where do you get the time and energy

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keef said..
>>>>>

im thinking about doing a molld with 1/3 of the base flexithane 85, with the comptesion the consistancy between a soft rubber and a break shoe peddle , if you lay the stainless into a mold with carbon and there is an overload , i'm hopeing the flexithane will oborb the extra pressure with out cracing the mold , what do you think

edit :" read your post and found its Bazils fin , you never seiese to amaze me , where do you get the time and energy

I'm not quite with you keef, do you mean when you have a lot of compression in the mould, or when the fin is in the board? I don't think you want anything soft in the fin, that'll probably lead to more problems.

Time isn't a problem, there's not much other than windsurfing that takes it up. Energy, well that's a different matter these days, certainly haven't got much for stuff I'm not interested in.

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decrepit said..

keef said..
>>>>>

im thinking about doing a molld with 1/3 of the base flexithane 85, with the comptesion the consistancy between a soft rubber and a break shoe peddle , if you lay the stainless into a mold with carbon and there is an overload , i'm hopeing the flexithane will oborb the extra pressure with out cracing the mold , what do you think

edit :" read your post and found its Bazils fin , you never seiese to amaze me , where do you get the time and energy

I'm not quite with you keef, do you mean when you have a lot of compression in the mould,

when you have a solid object in the mould like stainless with some layers of carbon and there is an overload, when you clamp the mould you have a chance of cracking it
if there is a 10 to 20mm layer of rubber or something that has a memory and wont stay compressed on the face of the mould , it shouldn't damage the mould ,
the fin may be slightly over sized so you will need to sand and adjust after de molding
the advantage is the stainless goes into the mould with the carbon and maybe some core mat it could save a lot of time and your mould, with the rubber inlay

my plan is to make two moulds , one solid glass and the other 30% flexithane for the stainless, ill let you know how it goes

flexithane is compatible with epoxy as long as you don't let the flexithane cure before you layup the epoxy

OK I'm with you, a slightly flexible mould, certainly worth a try, stainless doesn't compress too well!