Nof 'n Zaf KiteBoard Build Project

[plummet]

ok my advice might be moot as i have not built a kitesurf deck yet.

however i have build landboard, longboard skateboards but the same methods of manufacture.

i am building a estury board to put my landboard on at the moment to kite surf across estuaries on a big down winder i have planned.

anyway.

here's my 2 cents.

what ever you do don't steam and bend plys. it weekens the glue.

make a press and do it properly.

2 layers of 3mm ply and then one layer of uni direction glass 360gram either side should to the trick. (or 250-300gm carbon if you can afford it). Being a 30kg lad you want a light wieght deck. a 9mm plywood plank will be heavy as.

infact 6mm of ply would probably be enough. not for you but for him. i'd make the deck then glass a layer on the bottom and test it out. if its too flexi then glass one on the top.

all the computer modelling in the world isn't going to tell you jack compared to an actual test.

[plummet]

doh.

didn't realise this thread had 6 pages and started months ago.....

still way to much analysis and not enough building.

build it and find out.

if you get too tech you will end up with a snap crackle and pop board first up.

[SoutherlyBuster]

Thanks for your comments Plummet. First off the computer analysis is only as good as the inputs to the analysis. Just because the numbers come out of some fancy analysis program does not mean the answer is correct. The old saying garbage in --- garbage out.

Stress analysis is what I do for a living, so this was a just for the hell of it project because it interested me.

The analysis is not all purely computer based, there was some physical testing done, sample coupons of the ply were tested and loaded to destruction, this was then feed into the material model. The assumed loads are 2g, ie twice my weight of 70 kg. Yes granted it may break if that assumption was not conservative, but my engineering judgement tells me it will be OK, though Koma thinks 3g would be better. Let's wait and see when it hits the water.

So why analyse it appart from what has already been said? Well have building some frame kites and them breaking with out analysis being carried out, I don't want to put the effort into building the board only to find it breaks terribly.

Weight, well it comes in at 3 kg from memory, which is due to the hollow core construction. It's a 24mm deep section so I doubt there will be a strength problem, but again that is what physical testing is for. If I would do it again, I would pick a stronger ply.

If given the budget and time, I would strain gauge up a board, attach a data logger and give the board to Koma. Ok, buddy give it your worst and let's see what loads it is subjected to, land it hard, edge it hard and try to abuse it. Then feed this back into the computer model to improve strength were it is needed and remove material where it is not needed to keep the weight down. Flow analysis would also be done to reduce drag, but that is another story.

As for flex, this was just a gut feeling of what may work, again physically testing out on the water will show if it's ok. The computer modelling does however tell you how much it will flex for the assumed loads.

As for glassing or carbon fibre, my skills and equipment is for wood working so that is why I have choosen that route. Carbon fibre, way too expensive for this project.

I was not planing on steaming the plies to get them into shape. That is why I am strip planking it so the amount of straining during manufacture is well within the strength of the plies. I did some rough calcs and found it I made the first layer in one piece, due to the double curvature to would break. I'm planing on using four strips for each layer for the top and bottom. The inbetween plies where the hollow core is should be fine as one piece, they make up the internal ribs.

Regards,

Norman

[plummet]

24mm thick. really? for a twin tip......

it will be too stiff.

if you chose carbon you would need about 3m of uni at $30/meter. so its not an exsessive spend.

my thoughts are that you are over engineering it.

but by al means go ahead.

i await the picks. it should look sweet.

here's a good resourse for all things board building

http://www.kiteforum.com/viewforum.php? ... 10eb09fb74

[koma]

24mm thick. really? for a twin tip......

it will be too stiff.

I know you think it'll be too stiff but the Liquid Force Drop range of boards are ~25mm thick at their maximum so it's not unheard of in a production board. A stiff board can be a great thing whilst learning as it'll plow through the chop, but it will probably be a little down on pop. Either way, when Zac gets to the point where the board is holding him back i'm sure Norm will have v2 or v3 in production.

Koma the board torturer at your service!

[SoutherlyBuster]

Thanks for the link Plummet, after some spots checks of various topics this one will help for the next project:

http://www.westsystem.com/ss/

It's the epoxy that is water tight. Suspect this will be better than the hardware store grade stuff that is sitting in my garage and is always a hassle to get the amount of hardener right to have it cure. This epoxy is expensive but I guess it will last a long time and do many projects.

Regards,

Norman.

[plummet]

yep west system is what i use. punt for a 4 litre it lasts for years.

it will also be usefull when you step into composites as it can be used for glass/carbon aswell.

get glue powder for glueing wood.

[SoutherlyBuster]

yep west system is what i use. punt for a 4 litre it lasts for years.

it will also be usefull when you step into composites as it can be used for glass/carbon aswell.

get glue powder for glueing wood.

The glue poweder: is that the resorcinol? Bunnings have some thing similar. But I figured that the glue being used to form the ply wood in the first place (it is not marine grade) is not for water immersion, which means I have to apply a water proofing coat on the board in the end at any rate, so why bother with a fancy glue. So for the current project I was planning on just using ordinary Aquadhere, then use a final coat of marine laquer to water proof it.

Yes, I agree for the next project I want to use laminates of wood not already glued to form ply wood, in essence making my own ply wood, and then use the better glue, ie the West System.

Oh before I forget. Back to the flex of the board, because the section height is not constant, ie thick at the middle and thinning down to four sheets (12 mm, strike that out, it's 6 mm) at the ends, the board does have some flex to it, 10mm at ultimate load.

Regards,

[plummet]

i would flag the cheap glue and go epoxy. it will work for your next project too.

the epoxy will seal aswell.......

when using west system epoxy if you wish to glue wood (as apposed to laminate glass/carbon) its desirable to use a filler in the epoxy itself. sometimes called micro ballons some times glue powder. it adds thickness to an otherwise runny substance. fills in gaps in the wood and makes the job lighter aswell.

you get powder for glueing (aka glue powder) and also powder for filling not gluing.

12mm ply is way way way way way too thick for a kiteboard for a 30kg bloke. it will be heavy as hell and stiff as hell. are you sure yourve done your calcs properly?

[Fossil]

Anyone know where I can get stainless steel T nuts? I used to get them from Bolt In at Helensvale but they can't source them anymore.

I found stainless T-nuts online at;

https://www.bolt.com.au/index.php?cPath ... _1644_1689

Cost for the 10-24 unc are AU$168.08 per 100.

I phoned these guys and they said they would supply smaller qtys (@ $1.69 ea) plus around $10 postage.

I use 10mm thick aluminium, (sourced from scrap), and cut to around 15 x 15mm sq.

Bore a suitable sized hole in the core then epoxy the blocks in place.

You can tap the threads before or after mounting into the core. ( I tap the threads after mounting as I can accurately locate the positions from the perspex template I use).

I source my taps & drills from ;

http://www.ejwinter.com.au/catalogue.htm

Look up under the "tooling" section.

Fossil

[SoutherlyBuster]

12mm ply is way way way way way too thick for a kiteboard for a 30kg bloke. it will be heavy as hell and stiff as hell. are you sure yourve done your calcs properly?

Oops, should have wrote 6mm as per the slide, that part of the thread corrected. There is a some sanity to my perhaps madness ... sure the board is for my son of 30kg, but I will be the test pilot so it needs to withstand 70 kg and also with Zach's permission I would like to use it as a high wind kite ..... or should I correct that to .... "Dad .... build your own!".

As stated earlier the board will not be that heavy and the plies I am using are 0.75mm with grain top and bottom (this is the bit that gives the board the stiffness and strength) and 1.5 mm core cross grain (this is just a filler). Estimated weight before pads/straps 3kg. So I challenge you, how heavy is your board?

As for stiffness and have I got my calcs right, yes. If you look at the pictures the Youngs Modulus of elasticity in the grain direction is 11 MPa which is typical for the softer woods. This value was determined through coupon testing.

Thanks for the tips on the West system plummet, you've got me thinking now to use this instead.

Norman.

[SoutherlyBuster]

Plummet,

I have just browsed through the West System Resins, Hardeners and Fillers. There is no choice for the resin, just the 105 Resin, now it's down to the hardeners and fillers.

Since I want a nice clear finish to show off the wood grain, I was thinking to use the 207 West System Hardener, which gives a clear finish and is also suitable for structural joints and laminating. The working time is 110 to 130 minutes, plenty of time to get the pieces together. Also for the final coat, they say you can apply three or more coats in the one day. Sounds like the one to use for both the laminating and the final coat.

For the fillers, here it is where it gets a bit fuzzy. For the laminating part is a filler really needed for laminating wood? I would have thought you want the mixture nice and thin to keep the weight down provided there are no nasty gaps in the joint before laminating. As for filling blemishes, well I was hoping there would not be any of these, so why the filler for this project? I suspect I don't need it.

They also mention the 300 Mini Pumps for accurate dosing out of resin and hardener, this sounds a good idea.

Regards,

Norman.

[SoutherlyBuster]

There have been some PMs floating back and forth between Plummet and myself so I thought it's time to share our thoughts on this thread. Your comments based on experience were appreciated Plummet. So here is the summary of the use of filler additives to the resin for the purposes of kiteboard building where the main material is wood, which includes Plummet's latest thoughts and my thoughts in response and after browsing the WestSystem product selection guide some more.

As for the building stage, the form work is almost complete, I'll see if I can post some pics soon. I've placed one of the sheets on top of the form work, very light pressure needed to keep it in place. So for the shallow double curvature involved for this board, I don't need to strip plank it which will save me a lot of work. Just one whole sheet for each layer and some suitable weights on top to keep it in place whilst the resin is setting to at least the green stage. Will still need to do some scarf joints as the standard sheets from Bunnings are too short for the bottom couple of layers.

Regards,

Norman

[SoutherlyBuster]

I haven't given up on this project, just been lazzy to put the pics up on the web or the official excuse: the wind has been too good and been busy building the board.

I have a load of pictures since January 2010, so here it goes. Might to have to do it in a few sub threads, let's see how far I get.

31Jan2010:

Building the form work:

Building the form work. Form work will keep the plies in shape during lamination process. Rough cut read for filing.

Filed to shape.

Filing guide to keep it 90 degrees to workpiece.

Cutting off the ends, wooden guide clamped to board as cut guide to keep it 90 degrees to board.

After the cut.

More to come ....

[SoutherlyBuster]

The building continues:

2nd Feb 2010:

More of the form work. First look of the back bone.

14 Feb 2010:

Some more form work still to go, the sides.

Tools used to transfer the outlines from the printed drawings to the form work. Punch pin pricks through the paper onto the form work, then ink in the lines with a pen joining up the dots. With all the fancy curves you would not want to measure out all these lines, just print out the plan at a one to one scale, join up the pieces of paper with some paper glue and then transfer the image to the wood.

20 Feb 2010:

Form work all done.

Trial run, let's see if the sand bags keep the plies down without having to strip plank them --- YES can do in one sheet. This will save a lot of edge fitting. Because the double curvature is so gentle this is possible.

Now for the ply out lines. A lot of marking out to do.

Transfer the pin pricks.

Rough cut the sheet. Leave plenty of allowance as this thin ply tears easily.

Hold the sheet down and start planning.

To be continued.

Norman.

[SoutherlyBuster]

15 March 2010:

Gee has it been that long, wind must have been good!

Anyway,

The larger sheets need to be scarf joined. This is a tapper of 30mm for a 3mm thickness. Put simply the larger sheets that would enable me to make the bottom plies from a single sheet will not fit into my car. This type of joint may seem a bit daunting at first but if you take your time at first it is not that hard to do. Also because the plies are so flexible, any small irregularities will get taken up by the sheet flex during the glueing/clamp up stage.

Grandually plane away the tapper.

Right down to a knife edge.

The final scarf joint, one half.

More to come.

Norman

[SoutherlyBuster]

24 March 2010:

To cut the end grain a chisel is best rather than planning or sawing.

The chisel cut. Notice the very neat cut and no tear out. You will need a very sharp chisel for this, but a sharp chisel is a safer one, so all your chisels should be super sharp.

The resin, hardener and filler I will be using. The filler is only for the exterior blemishes. Just some extra notes on the resin. This was purchased from Power Drive Marine (Williamstonw, VIC), the fellow there, Rodger was very helpful as he has used this West System resin before with wood laminates. The 105 resine doubles up as both laminator and final finish, though the final finish needs 2 to 3 coats but is not that UV resistent. So if you are worried about UV resistence then a good marine varnish would be in order.

The 205 Fast hardener was recommended for the Melbourne conditions in March when it is a bit colder. The slower setting hardener will take too long to set and will take on too much moisture which will make the joint weak.

The 410 Microlight Ultra Light Fairing compound is for the external blemish fix ups. It does not increase the viscoisty when added to the resin which is extactly what you need to get good penetration into the wood grain.

For the mixing of the hardner and resin be precise and do not change the ratio of hardener to resin to make it set slower or faster, use what the manufacturer recommends.

Ok, back to the scarf joints ... A test piece of a completed and glued up scarf joint --- just to see if it works! Can you spot the join line?

28th march 2010:

Now for the internal plies, the ones that have lightening holes. The holes are there to make the board lighter. The internal ribs that are left behind are to transfer the shear loads between the top and bottom plies, and near the foot pads to take the crushing loads from your feet.

The first two bottom plies, scarf joints all done.

This portable table prooved to be easier to use to clamp the sheets down on for shaping. Though if it were a little higher up this would be easier on my back, especially for the routing bits (this to be shown further on).

After the deep cut planning to remove most of the material.

After the fine cut planning, the final cut.

Next come the lightening holes ... stay tuned ... more to come.

Norman.

[SoutherlyBuster]

1st April 2010:

Now for the lightening holes. First attempt, trying using a coping saw --- this is the hard way.

2nd April 2010:

The more efficient way, using a plunge router, now I'm cooking with gas!

Some of the lightening holes cut.

A detail of the routered cut. The cut does not need to be perfect like the external edges as this will all be covered up by the top and bottom plies and will never see the light of day again.

Safety first when routing: dusk mask, safety glasses and ear muffs. They are dusty and noisy machines!

Some more lightening holes.

5th April 2010:

The finshed product. There will be a scarf joint for this one. But in hindsight, using a single sheet would have been easier as the long thin free ribs vibrate easily when routing and require great care so as not to take off erronously a big chuck.

To make the process of plunge routing the lightening holes quicker, I will form the out side shape of several sheets, temporarily fasten them together and plunge route them all in one hit, then do any minor fix ups where the different sheets have slightly longer lightening holes at the board ends.

Well that's all for the moment until I build some more. Now, what is the wind doing?

Regards,

Norman.

[Wazza1]

G'day Norm. Looks like it's coming together well.

I notice in one of your pics the drawing template for the board looked like it was done using separate sheets of paper stuck together. I did that for a while then found my daughters art easel had a great roll of suitable paper about 60cm wide on it. Just perfrect to create the template for a board on without having to stick sheets together. Just a thought.

Keep the updates coming. W

[SoutherlyBuster]

I notice in one of your pics the drawing template for the board looked like it was done using separate sheets of paper stuck together. I did that for a while then found my daughters art easel had a great roll of suitable paper about 60cm wide on it. Just perfrect to create the template for a board on without having to stick sheets together. Just a thought.

Keep the updates coming. W

I've been thinking along similar lines using the old fashion computer paper with the perforation lines, but did not think of the art paper roles, my son might even have some of that left over. The trick is getting the printer to use such a long towel software wise. For the board it was not so painful glueing together, but when it comes to foil kites, this can take a month or two to print the sheets out and glue together.

What I need (oops, dream of having) is a CNC controled cuter, miller, do the design in cad and feed the rest into the miller. Actually a friend of mine built one at home, talk about being keen.

[Fossil]

le Plank 1.1 had it's first outing today, and I managed to get up on the plane a few times with it too. A couple of things I noticed were that it tends to "submarine" a bit, I think this may be due to the small amount of rocker it has and the square corners which kinda catch on the swell a bit. Considering whether or not to take them in to say, 400mm or something (450mm total board width).

Also, the DIY footstraps are secured too far from the edges of the footpads so my feet tend to slip to one side or the other, but that should be easy to remedy with a drill .

Apart from that, it seems to be a bit of a winner!

Have a look at these straps http://www.oceanculture.com.au/index1.html

Can bid for them on Ebay or buy them for around $37

Fossil

[lais817]

Thanks Fossil, might be on the cards, but I think I'll just save me dosh for a decent pre-made board lol! Norm, that thing is looking very, VERY nice if I do say so, I'm dying to know what it's gonna look like, you should have a "design-a-deck-for-the-Nof-n-Zaf-KiteBoard-Build-Project-Project-Board

Again, can't wait to see the finished product, hope you and yours have been well!

[SoutherlyBuster]

Thanks lais817. Personally I think it's best to start with a professionally made board (or kite for that matter), then start experimenting with ones own designs. We're doing fine down here in VIC, but no wind, no Southerlies, no water action. So it's more of board building time. I'm at the stage of having four or so plies all temporarily doweled together (dry joint) and machining out the lightening holes with the router. My car in the garage is getting a peppering of dust and my wife keeps on telling me to drive her car out of the garage before generating all that dust . In a week or so I'll be ready to plane up the final ply, the party time to glue them all together.

Regards,

Norman.

[Morandi]

SB Said: The 105 resin doubles up as both laminator and final finish, though the final finish needs 2 to 3 coats but is not that UV resistent. So if you are worried about UV resistence then a good marine varnish would be in order.

Hi SB. Given you are going to such impressive lengths I would recommend adding UV stabilisers to at least the final layers of resin. If not you will eventually get yellowing, - importantly for a kiteboard- loss of flexibility and therefore strength. [i realise that the board is not meant to last Zac's entire professional kiting career but it will a different significance!]

As you suggest, a final coating of stabilised varnish will help, but to contribute to this impressive thread I will suggest stabilising the entire board resin.

There are two types: ultraviolet inhibitors (kind of like UV absorbers) and radical scavengers; ideally you would use both. The radical scavengers are liquid hindered-amine light stabilizer (HALS) which are regenerative scavengers that reduce bond scission from within your resin. The chemistry of both of these is pretty impressive and should show a marked longevity of your board both aesthetically and structurally.

These additives are used in most exterior coatings - domestic paints and cars - so the problem is getting small quantities as you only need 0.5–3% to the weight of the resin. The products I know are Tinuvin® made by Ciba-Geigy (Tinuvin 327 being a UV absorber and Tinuvin 292 a HALS) but there are many others.

PM if you need some help.

Morandi

[SoutherlyBuster]

Hi SB. Given you are going to such impressive lengths I would recommend adding UV stabilisers to at least the final layers of resin. ...

These additives are used in most exterior coatings - domestic paints and cars - so the problem is getting small quantities as you only need 0.5–3% to the weight of the resin. The products I know are Tinuvin® made by Ciba-Geigy (Tinuvin 327 being a UV absorber and Tinuvin 292 a HALS) but there are many others.

PM if you need some help.

Morandi

Thanks Morandi. That is valuable information. I will do some research to find sources of the UV stabilisers. Yes would be a shame with all the work I'm putting into the board only to be wrecked by UV degredation. Might just talk to the fella from Power Marine where I got the resin from, they might just have the additives I'm after.

Regards,

Norman.

Ok, some more ... a quick look at the West System web site and their search engine for UV resistence came up with this:

http://www.epoxyworks.com/18/pdf/varnish.pdf

They recommend West 105+207 combination three coats of the exterior wood, then apply a UV resistence marine varnish. They also state this is better than the two part expoxy plus UV resistence chemical. Ok, Dr Who is back on, will look more later.

Norman.