plywood`s ride - the beginning

[plywood]

first of all:
yes, mine is about 6" wide as you said. of course you also could use a continour carbonfibre.

i also had this option in my mind when i built my heating. as i said, i first wanted to build one single heatingsheet with 2m of lenght. as i calculated how many rovings i had to connect parallel i became the result 0.3 - and you can not connect 0.3 rovings. the minimum is, logically one! and for just one roving of the kind they are used in my hybrid-band there would result theoretically a heat of abour 30degrees. far away from what i needed.
now i think if you would use a lighter sort of carbonroving than the one which is used in my hybrid band, you would become a greater heat (because of the higher electrical resistance of a thinner fibre).
this would have been my plan b. but i can not say how the calculations would be done in this case. the probelm is, that you would have to measure the electrical resistance of the carbonfibre you want to use. if you can measure this, the rest isn`t a big deal and more or less the same as i described it.

secondly:
dded yeah. i got some freetime today and had the glorious idea to test my vakuum-setup. and i really have to say: i hate it!
it just backed up my experiences with vakuum - and my experiences were bad. it`s nearly impossible to get the things thight...and if i put out my vakuumpump just for a minute the pressure gets lost, even if i tried nearly everything to thighten everything. so...it proved one more time that i can not trust this vakuum thing. damn.

well...this means i got to meditate again, feel the spiritual vibes and positive energy of my still unexisting ski...and to hope for a divine inspiration to solve my pressing problem
no, seriously - i think i`ll transform my vakuum mold to a bladder press. i just need a bladder and a press frame...so this isn`t a big deal.

so, i`ll keep things as simple as possible. for the bladder i`ll use a fire-hose and a valve of a bike tube, like this guy did it. hope this works, but a pressure of 4-5 bar isn`t that much...so i`m full of convidence that this time everything works.

if i still can realise my special tail-idea.... i don`t know. this is the only sad part of the story.

[Jordan]

how do you make your skateboards?

[plywood]

as i wrote somewhere on the first side, building a skateboard is nearly the same as building a ski.there are some differences between freestyle skateboards and slalom-/longboards. i just build slalomboards, and there you use a sandwichconstruction: woodcore, fibreglass on top and bottom.

i press the boards with a selfmade press which i got from a friend of mine:



as you may see on the picture it basically uses 2 car jacks to lift the lower bar of the press (this one looks like a big U). so the upper part is fix.
the car jacks lift 6t each. so i have a pressure of 12t on an area of 20x80cm.

this would result in a pressure of 75t per squaremeter or about 7.35bar (1bar is approximately 10.2t per m2)

during pressing i heat everything with a heating sheet (described on page1) up to about 60-70°C. with this setup everything stays in the press for about 5hours at least.
heating up everything not just makes everything cure faster, it also creates a nicer/smoother/planer surface...that`s what i believe.

so, now you know nearly everything about how to build a skate.

[Jordan]

I was just wondering why you dont use the same method for making your skis, now i know... because your skis wont be 30" long. I thought you were maybe vac bagging.

good to see another skateboard builder out there.


www.circuit-skates.com

[plywood]

hehe yes, that`s the problem. my press can be loaded with boards with maximum 45" - still way too short for a ski

really professional work with your skates! i didn`t know how far snowskating progressed! was interesting to check out your page

[plywood]

well, an other weekend passed.

my girlfriend went to zermatt for skiing - so, what does this mean? first of all: winter`s coming, as she told me. secondly: i had plenty of time for skibuilding
and because winters coming unstoppable, i have to hurry a bit.

i became some firehose at friday and cut it in lenght. maybe i find some time to finish the bladder during the next week.

basically i spent the weekend with cutting out the bases. first i built the template. i took some 3mm MDF and cut out a half of the shape with a jigsaw. the final finish of this half-shape-template took quite a long time, tuning everything with a file.

later i took the 3mm template and fixed it with some clampings on a thicker,5mm MDF sheet. then i "transferred" the outline of the half-shape-template to the thicker sheet with the router and a router-bit with bearing. after finishing the outline of one side, i mirrored my template around the longitudinal axis.

this metod should garantee a "perfectly" symmetrical shape of the ski.



davide sent me some green and yellow base materials. so i wanted to use the green one for the first ski, because i really like green at the moment. but JUST two green bases seemed to be a bit boring...so i tried some simple die-cut grafics. i started with one base and i wanted to cut out some green/yellow squares. well, cutting the base with a sharp knife was not a problem...but assembling the several pieces was kind of tricky - i used some adhesive tape to hold everything together since the superglue didn`t glue so super...so after one base my lust for cutting the second one was gone
hopefully the part with the die cut grafics will stay together, otherway i`ll become a crooked ski

after these experiments i clamped my 5mm template on the base material an routed everything out. it worked just fine...but you have to pay some attetion to in which direction you cut things: you have to cut everything up-ward (in german:gegenlauf), otherwise you get some horrible brows.



i also built an edge bender...but even with such a tool, bending the edges is still a unconfortable affair...but it works more or less.

[plywood]

again - some days of building!

a week or so ago davide came to visit me and gave me some tips - thanks a lot again for sharing.

as i said, i don`t trust the whole vacuum-setup anymore. so i had to change my plans. my new press should also work with airpressure and a bladder, like the most of you use. but it should be as easy, cheap and small as possible.
i saw on this forum a guy who made a bladderpress with an air valve of a biketube in a firehose. so i did the same. and it works quite well. until now i only tested it ub to 1bar because i was too lazy to put more effort in pumping the bladder up - it`s quite exhausting with a normal biketubepump

so, i`ve planned from the beginning to operate with relatively "low" pressures, maximum 2 bar. i think this is way enough pressure to get some good results, if you compare things with vakuum.
an other advantage of operating with "low" pressures are the dimensions of the press frame.
first i wanted to make a construction with threaded rods....but i found a better way:
my mother had some special cloth, so i sew some tubes with it to wrap around my molds. so you can see everything on the pics:

[Chicagoskier11]

do you have to do anything special to attach the tire valve? I want to do the same thing. Do i just bond it into the hole or do you put a washer on the inside? I just don't want it to shoot out under pressure. Thanks.

[plywood]

well...i don`t know how it works with higher pressures.... but that`s the way i did it:
the diameter of the tire valve is about 11mm or something like this. i drilled a tighter hole into the firehose, about 10mm. so i had to use some force to put the valve through the hose.
to prevent the valve from being shot out you have to left over some rubber of the tire. when i cut out the valve out of the tire, i left over the tire in an area of about 5cm radius around the valve.
so you have a pretty big area to glue to the inside of the firehose. for glueing it together i used "shoemaker-glue" (in german: schusterleim)

i don`t think that the valve will shoot out. first of all you have a relatively big area wich is glued to the fire hose and secondly you have quite a small hole through the hose...
and valves of bike tires normaly hold out easily 4bar and more

[plywood]

rock`n roll, babe!

well - the newest progress of my building process:
i built my woodcore, out of 7 plys of 1.5mm thick ash veneer. so i got a final thickness of 10.5mm. i pressed the wood with a bit more than 1bar, maybe 1.2 or something. this is really enought pressure...i profiled the core like this:



for the 12cm/20cm middlesection i got inspired by the skigallery of the great skibuilders...it just seems to work great, so i copied it. the thickness is a result of my horizontal core and the several sheets of veneer.

profiling the core wasn`t a big deal and nothing special.

so, as i had some honeycomb laying around at home, i thought i could make some "inserts" with it to reduce the weight of the core. i designed the inserts in a way which would still allow a maximum of torsional an longitudinal stiffness.
as you can see on the pic below i left over some kind of big crosses. i think this construction is the best for my purpose. because i wanted to have a more flexible area in tip and tail, i "stopped" the crosses about 8cm before the end of the effective running lenght.



the blue line shows the overall lenght of 177cm, the red one stands for the lenght of the effeective running lenght - 148cm - , and the green ones are the 8cm described above.

on the picture you can see these X. i planned to cover them with some small strings of carbon during layup. this should result in a maximum of stiffness and in a minimum of weight - just apply some material where it`s really needed. it`s also a possibility to tune the flex in a very effective and precise way


in the area around the tip the honeycomb inserts fully replace the wood. the honeycomb is 3mm thick and so is the wood. i think i`ll have to put there an extra layer of glass to protect the honeycomb from damages caused by hitting rocks etc.



you might ask yourself now: how much does this construction reduce the weight?
well....it`s about 40g. ...and without having glued the honeycom to the core. so i`m glad if this crap finally doesn`t make my core even heavier!

so, in conclusion: if you want a huge amount of extra work, ruining the stability of your woodcore and become an even heavier, weaker construction, honeycomb definately is the way to success

hopefully it works in the end and stays together for at least one season...

[alexisg1]

so, in conclusion: if you want a huge amount of extra work, ruining the stability of your woodcore and become an even heavier, weaker construction, honeycomb definately is the way to success

:lol:

Nice job ! It's seldom to see people trying to custom their core thus way.
I can't wait to know how it works !

[plywood]

well, time`s running out, snow`s coming - HURRY!, i said to myself.

so, after having the cores done i routed in a channel for the edges on the downside.

then i bent the edges so that they fit to the base. somehow i got the impression, that the edges are the hardest part of skibuilding: first of all to become them somwhere, then to bend them!
but i won the fight against the edges and finally got them more or less properly bent. for the piece that goes around the tip i used a leftover and flame threated it to destroy the temper. so i could bend them easily and they still protect my core from damages.
attaching the edges to the base wasn`t a big deal. i sanded the edges and cleaned them with a silicon-remover. this will guarantee that the edges are really clean and free of any grease/sweat (caused by touching them without gloves).

but now for something completely similar: the layup

as i announced in my older posts, i planned to work with carbon strings to reinforce and apply strenght just where it`s needed. as you can see below, i started with putting 3 stripes directly on the base (220g per m2, 25mm wide each). first i just wanted to use 2 of them, following the edges. but just before i begun with glueing everything together i had some doubts that my construction would come out too weak, so i added one more carbonstripe.



the stripes were followed by a 308g/m2 biaxial layer and unidirectional carbon with 140g/m2. i also added some partial reinforcements for the areas with honeycomb in tip and tail.

then i placed the woodcore. to protect the ends of the swallowtail from damages, i replaced the last 2-3cm of the woodcore with 3mm thick aluminium plates.

glueing the honeycomb into the holes was also done quickly. i just had some problems with the honeycomb-insert in the tip because the woodcore already relaxed a bit and didn`t fit to the mold properly.....hopefully it works anyway and the cells don`t got filled with epoxy...



here you can see the top of the woodcore with the reinforcements for the binding-screws. i glued there some extra glass so that the screws don`t get ripped out. now you can also see how the carbonstripes build these big crosses to prevent torsional stiffness.

so, the whole thing was followed by an other layer of 308g biaxial fibreglass and 160g black colored fibreglass fabric. mainly for the cool black optic. and of corse i used also a topsheet.

well... the grafic....i tried things out before layup, these tests all came out quite good - but on the skis something went wrong and the color blured...

but - i can not say how bad it is, i also can`t say if this method leads to success, if it even nearly works, because the ski is still in the press. i`ll find out today in the eveneing

[plywood]

well...now i`m waiting for a week...
the dudes from swiss-composite just delivered me 10m of 25mm wide carbon strings instead of 25m - so it just was enough material for the first ski, and now i`m blocked.

so, hanging around and waiting for the stuff really sucks! but this is not enough: we also suffer a lack of snow. it just dumped once this year and in most of the resorts the slopes are hardly skiable - skiing offpist impossible...

so hopefully i`ll get my stuff today, otherwise i`ll lose another week

[plywood]

time passed, skis finished, pc collapsed - and that`s why it took so long to public these pictures here:

so i managed to finish my first homebuilt ride. so, the colour of my grafic faded somehow during pressing...
grafics were done by drawing them on the back of the topsheet. during layup i met there some sheets of white paper...and then somehow the epoxy liquidated the "waterproof" colour (well, on the testings i made bevore, the colour stayed in place...)



so on the tip it should stay "plaiwud" , some mixing of "plywood" with the phonetic script of it. on the tails i drawed two swallows. that`s also the name of my model - the swallow. well, you can guess why it`s called the swallow. yes, because of it`s swallowtail. and the swallow is a nautical symbol and stood also for a lucky return - and that`s what we all can need in the backcountry, right?

so these skis have 146-112-136 and are 177cm long. one ski with binding weights 3300g. camber should be 9mm: the right ski has 9mm, the left one only 7mm...no idea what went wrong there

in the coming week it should snow again here in europe so i`m hoping to take them out for the first ride!

[RoboGeek]

Looking good! The blurring just adds an 'artistic' touch!