A bambus? Sto da kazem?
Dvije su vrste bambus sperploce (ili bilo kojeg lijepljenog bambus proizvoda), horizontalno i vertikalno zalijepljeni. Za ovaj projekt izrade kiteborda, odlucio sam se za horizontalni, jer ce se savijati bolje po duzini daske (manje) i nesto manje po sirini daske od vertikalnog.
Receno mi je potpuno suprotno za vertikalno ljepljeni bambus (probao sam, previse je savitljiv).
Napravio sam probu! Zalijepio sam dva komada sperploce prije 10 dana (razlog kasnjenja novog clanka). Ovo je izmjereno od "sredine" konkave i iznosi 11 milimetara!
No, malo sam i iznenadjen! Sto se desilo: Nakon sto sam savinuo drvo i zalijepio, ostavio da se susi i nakon 24 sata otpustio stege, nije bilo konkave skoro uopce. Tako da sam zaboravio na to:)
No 7 dana kasnije pogledao sam ponovno - 11 mm konkava! Kako? Ako je bambus bio suh (da, mora se osusiti prije lijepljenja), mozda je pokupio vlagu i rasirio se? Kako ce to djelovati na dasku? Vidjeti cu.
I was thinking to use two layers of marine plywood to get the rocker and concave nicely shaped. But than, I got some bamboo plywood 5mm thick and decided to use that instead. Bamboo can be sanded well to get the thinner board tips. It is very strong in one direction and will bend well. Looks like the marine plywood is hard to bend and it will be even more difficult to bend it in 3D (three dimensional).
But bamboo? What to say?
There are two versions of bamboo ply (or any glued bamboo product), horizontally and vertically glued. For this kiteboard project, I went with horizontally glued, since it will bend much better (less) with the board length and slightly less in the board width direction than vertically glued product.
I was told exactly the opposite for vertically glued bamboo (tried it myself, too flexible in my opinion).
Let's test it! I've glued two peaces of ply 10 days ago (hence the delay of this writing). This is measured from the "middle" of the concave and it's 11mm!
But, I'm confused. What happened is: I've shaped the concave when I glued this, left it to dry, and after 24hrs released all clamps. There was almost no concave at that time. So I left it and forgotten about it:)
7 days after, I've checked and there it is - 11 mm concave! How? Was the bamboo dry (yes, I did dry it), and now got the moisture and bent? How will this work on my kiteboard? Time will tell.
~The top bamboo layer is now cut and ready for sanding (to thin the tips).
~Any finally, I've got almost all parts for the vacuum pump. More about this some other time...