plywood`s ride - the beginning

Document your personal work here. Show photos, movies, and share your secrets.

Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp

G-man
Posts: 600
Joined: Sat Mar 25, 2006 3:58 pm
Location: northern sierra nevada

Post by G-man »

Very nice, plywood. Back in my bicycle building days, I sometimes used a candle to apply soot patterns to the paint job before applying the clear topcoat. It became quite popular. When I first saw your pictures and before I read about the ink bleeding problem, I thought you had figured out how to do that on a ski. Actually, it probably would be pretty easy to do, but I would think that the soot (carbon) would interfere with the top sheet bond. Anyway, the skis look great, and I like the 'smokey' graphic.

G-man
alexisg1
Posts: 110
Joined: Fri Dec 08, 2006 12:38 am
Location: Grenoble, FRA

Post by alexisg1 »

RoboGeek wrote:Looking good! The blurring just adds an 'artistic' touch!
I totally agree with that, very nice skis !

I am very curious about the stifness of the skis because of the carbon strings...I hope it will bend somehow ! Let us know !
plywood
Posts: 499
Joined: Fri Oct 13, 2006 2:13 am
Location: wilen, switzerland
Contact:

Post by plywood »

thanks for all the nice comments! can`t wait to ride those things! :D

@g-man: what do you mean exactely with "the soot/carbon would interfere with the top sheet bond?" because somehow i can`t imagine getting some problems by paintin the topsheet the way you described it - if i understood everything right
alexisg1 wrote: I am very curious about the stifness of the skis because of the carbon strings...I hope it will bend somehow ! Let us know !

of course they bend! from my experience i can say that a sheet of 140g/m2 unidirectional carbon is as strong as a sheet of unidirectional fibreglass with 220g/m2. and i just used 3 strings of 25cm wide and 220g/m2 heavy carbonstrings between base and woodcore. they don`t cover the whole area, so i`d say the have the same stiffness as a full sheet of unidirectional carbon with 140g/m2. these strings are covered by a layer of 140g/m2 unidirectional carbon.so all in all i used approximately 2 layers of unidirectional fibreglass with 220g/m2 for the whole ski- and that`s more or less equivalent to the amount of unidirectional glass in 2 sheets of triaxial fibreglass with 220oz as most of you use. if my calculations and guessings are right ;)

so these skis are a tiny little bit stiffer than volant machetes i ride. but i have no comparison with other skis because i`ve never ridden some other skis than the machetes... so i`ll see if this tiny little bit is too stiff.
plywood freeride industries - go ply, ride wood!
G-man
Posts: 600
Joined: Sat Mar 25, 2006 3:58 pm
Location: northern sierra nevada

Post by G-man »

plywood,

Two ways I used to do the smoke effect... one was with a candle flame right up against/underneath the paint job and moving the flame slowly along. Putting the flame against a surface decreases the combustion efficiency of the flame and causes an inefficient burn, resulting in increased smoke and soot formation. The soot is then deposited on the surface in an interesting design. Another way to do the soot thing is to use a kerosene lamp with the wick that is too long. You can adjust the wick length with the elevation knob to get as much soot production as you want.

Maybe soot deposition on the bond surface of the top sheet material wouldn't effect the bond strength... don't know. Lately, I'm generally inclined not to do anything that might interfere with ultimate bond strength until I get a better baseline for what the best obtainable top sheet bond can be, then I'll work backward from that point to test how different graphics methods effect long term top sheet bond strength. I've even stopped using cloth color layers for the time being.

Another thing that may be worth considering with the candle/soot method is that the heat of the candle flame might alter or destroy the surface treatment that was done at the factory (flame treatment). That would also decrease final bond strength. You could always do a test piece and beat the crap out of it and see how it holds up. It would be a pretty neat effect if you could get it to work.

G-man

P.S. I just did an experiment on a plastic milk jug (HDPE). I smoked it, then sprayed clear lacquer over it. It seemed to stick pretty well... looked good, too.
User avatar
RoboGeek
Posts: 239
Joined: Wed Jan 17, 2007 12:08 pm
Location: Middle of a cornfield...

Post by RoboGeek »

another way is with an oxy-acetylene torch with the O2 turned off. The soot is almost like a carbon thread. We used it doing custom paint effects on cars. I would assume that it would bond as well as carbon fiber, but I'm not sure if it would bleed. It worked ok with clear enamel auto paints
collin
Posts: 105
Joined: Sun Oct 23, 2005 10:19 pm

Post by collin »

RoboGeek wrote:another way is with an oxy-acetylene torch with the O2 turned off. The soot is almost like a carbon thread. We used it doing custom paint effects on cars. I would assume that it would bond as well as carbon fiber, but I'm not sure if it would bleed. It worked ok with clear enamel auto paints
Perhaps not surprisingly this also happens with a cheap MAPP/Ox torch from a hardware store. Which is my I currently have soot all over my living room. :?
------------------Take nothing I say as expert advice------------------
davide
Posts: 260
Joined: Wed May 04, 2005 7:13 am
Location: Tsukuba, Ibaraki-ken, Japan
Contact:

Post by davide »

Nice, you have finally managed to finish them. Will the 30 cm of new snow be enought?
It seems it was a good idea to come to Japan.
plywood
Posts: 499
Joined: Fri Oct 13, 2006 2:13 am
Location: wilen, switzerland
Contact:

Post by plywood »

thanks for all your explanations about the printing methods! sounds interesting, maybe i`ll try this out some time.

@davide: yes, they`re nearly finished,but they still need the edge tuning.
well, the stuff with the fresh pow...it got really colder now! on my place we have about 10-15cm of snow and even the streets are covered. so it looks kind of good! and it snowed all day long, so i`m hoping that it dumped even more in higher regions. maybe i`ll go to andermatt/oberalp tomorrow for a first testride. and maybe from friday to sunday or so for a short trip to davos - they have the world-economic-forum there, so lot`s of police, security...and no skiing tourists :D

an other question: as far as i know you use the same resin as me, epoxy typ L from swiss composite. i looked up some datas of this resin and found out that it only holds up to 65°. so my question: never had any problems with waxing?
because i don`t know how serious you have to take these 65° - i`m using this resin also for my heating sheets, and there the temperature often is higher than the 65° - and i never had any damage...so i just wanted to know what you think about this....

so, when are you coming back from japan? because next week it should get warmer again here :(
plywood freeride industries - go ply, ride wood!
plywood
Posts: 499
Joined: Fri Oct 13, 2006 2:13 am
Location: wilen, switzerland
Contact:

Post by plywood »

i did a first testride yesterday, trip report you can find here: http://www.skibuilders.com/phpBB2/viewt ... =3845#3845
plywood freeride industries - go ply, ride wood!
mattym
Posts: 51
Joined: Tue Jan 23, 2007 10:15 am
Location: Fernie BC, and Falls Creek Australia

Post by mattym »

dude, as was said the whole way - so interesting to read your work, and follow your progress. And as I've already said - such a sick pair of skis!!!!
Anyway, was wondering if you managed to still incorporate your heating mechanism into your new press design (which kicks ass mind you).

Do you have any idea what material that cloth is?!?! And any idea how many bars pressure it could take?? And finally, :), how did you sew it and what did you sew it with so that it would hold up to the pressure?
plywood
Posts: 499
Joined: Fri Oct 13, 2006 2:13 am
Location: wilen, switzerland
Contact:

Post by plywood »

no, i didn`t incorporate the heating. as i had to split it up into two heating sheets it would create a gap in the middle...also the connections of the fibrestrings which i made with wire would create some problems because the kind of stick out.
but it would be possible to use such heating sheets, even split up ones, if you would construct them better: you could connect the several carbonstrings (without putting a wire in between) by just fixing them together with a filament. after laminating this would also hold and you had a plane heating sheet.

well, about the cloth...i just can say that it is cloth from schöller (maybe you know this manufacturer, they create some special cloths, also for sports suits and skiing jackets etc.) it was made for motorcycle suits so it`s a bit stronger and should have a higher tear-resistance. no idea how much pressure it could take. but i don`t think that the cloth would crack: the weakest point of the construction is the seam with the stiches. so i suppose that the seam would be teared apart first.

Image

well i sewed it with a normal sweing machine. the cloth isn`t extra thick or something like this, it was no problem at all. i also didn`t use special thread, just sewed a few time over the whole seam.

EDIT:
ok, cloth-update! i`ve spoken with my mother. if you work with cloth you have to pay attention to following: cloth is woven. so in one direction the filaments are spanned and in the orthogonal direction the filaments go kind of up-and-down "around" the spanned ones. so you have to consider this - you should make the cloth-tunnel for the "pressframe" so that the spanned filaments lay in direction of the load - otherwise you become a flexible tunnel, and that`s not what we want, right?!
then: if you`re gonna operate your press with maximum 3bar i suppose a bed linen would also work as a press frame - if you take it doubled. my mum just told something that bed linen are made of cotton and that cotton reacts on humidity, so you may also have to consider this. so some synthetic cloths would work better for this.
so it`s not that easy to recommend an exact type of cloth to recommend. but you can make some basic calculations: 1bar is approximately 10,2t per square meter. the area you`re gonna press is about 0.27 square meters (15cm wide and 180cm long, apporimately the dimensions of a ski). so if you press with 3bar you get 8,262t load for your press. if you divide this throug the lenght of the press (180cm) you get a load of 46kg per centimeter. so each side of the press has to carry 23kg per centimeter of lenght.
and now all engineers hair stand on end regarding my calculations :D
but i`m nearly sure that they work approximately well :)

and now the last part that you have to consider working with cloth: you have to sew such a piece together so that you get a tunnel. the seam you got is the weakest part of such a construction. so be sure to leave enough cloth to make a broad seam to distribute the load on this part. i`d recommend to leave about 10cm for the seam. that should be enough. and then you just have to sew a few times over the whole lenght and everything is fine.

so the calculations above can be used for your guessings. 23kg load on every 1cm-wide stripe of the tunnel is not that much. so you can appreciate if the cloth you got can hold it up. if it wouldn`t hold up your pressframe wouldn`t burst immediately - i suppose it would continually tear your seam apart.[/b]
plywood freeride industries - go ply, ride wood!
mattym
Posts: 51
Joined: Tue Jan 23, 2007 10:15 am
Location: Fernie BC, and Falls Creek Australia

Post by mattym »

alright, well i think i might have found the cloth you speak of!

http://www.schoeller-textiles.com/defau ... 8&langID=2

It looks like it would make an awesome 'pressframe' - 5 times stronger than steel gram for gram!! Click on the PDF link - it has some good info there too!!! Think im going to have to investigate prices and what not a little further.

Do you think a single sheet of this, ie. one large tunnel that holds the entire mold, stitched together would be the way to go?
plywood
Posts: 499
Joined: Fri Oct 13, 2006 2:13 am
Location: wilen, switzerland
Contact:

Post by plywood »

wow, super link. but my cloth isn`t that radical.

i`ve not found it on the internet. maybe because it`s not one of schöllers own cloth - they also manufacture cloth for many other suppliers/industries....

but this would sure made an awesome frame. but i`m afraid that it`s not that cheap...

difficult to say if it would hold out since there are just pictures. but i`d suppose that it would last. as i said - the load isn`t that big, also 2 bed linen could take it.
i`d recommend to look for a synthetic cloth that is a bit stronger than normal one and which not so expensive...and then just try! but no matter how strong cloth you take, the seam always is the weakest point of this cunstruction.

just something about the tunnel: i`d recommend to split the tunnel up in two half so that you can attach it from every side. a lot more confortable than just one piece which you had to pull over the whole mold.
plywood freeride industries - go ply, ride wood!
mattym
Posts: 51
Joined: Tue Jan 23, 2007 10:15 am
Location: Fernie BC, and Falls Creek Australia

Post by mattym »

haha yeh I kinda thought that may be a little extreme - but if you could find it for a decent price it could perhaps hold more pressure than say bed linen....

Id like to find a different way to join the cloth other than stitching, athough this seems to work. Do you think there are better ways?
plywood
Posts: 499
Joined: Fri Oct 13, 2006 2:13 am
Location: wilen, switzerland
Contact:

Post by plywood »

well...sure there would be other ways to put the cloth togeter...but i don`t think that any of these ways is as strong as sewing...

you could glue the cloth together - but this wouldn`t be a very strong connection and the area were you glued it would be kind of sensitive...

you could make some leashes so that you could lay the press on the cloth which is laying flat and outstretched on the ground. then before pressing you could lift the cloth on each side so that the leashes are on the top over your mold. there you could connect them somehow that you get a tunnel for pressing - this would be more confortable during layup/installing the pressframe would be easier...but there would result a higher load on the leashes. so i suppose this connection would also be weaker than sewing.

well...what else could you do... oh yes, you could take a very long peace of cloth, so long that you can wrap it around your mold at least 3,5times. then the cloth creates a static friction which is big enough to hold it - not a very serious suggestion ;) it would work, but on the beginning it would stretch your cloth a bit so it maybe was too flexible.

so in other words: there are other ways, but none holds out as much as if you sew it. look at lifting straps - no matter how heavy things they carry, practically all kind of lifting straps i know are sewed.
plywood freeride industries - go ply, ride wood!
Post Reply