OOAK Table Tennis Forum

I am trying to make my own blade.
Is it a huge problem if all grains are vertically oriented. Because I read somewhere that blaade may warp if layers are all oriented the same.
How huge a problem is this ?
I am primarily concered about the core. I bought two 6 mm sheets of balsa but they ar cut lengthwise. I wan to make a 12mm (6=6) core with these two sheets. How big would it be a problem if i have both core blasa woods oreiented lengthwise. Would this cause lot of blade warp ?

Are there other tips & tricks to prevent blade warp ?
Any help is appreciated.

In most blades the core is a single sheet, so naturally there is one orientation of grain. I don't see much difference between a single layer and two layers with the same grain orientation. The latter could perhaps be slightly stronger because the grains won't perfectly align, plus there is a glue layer.
I personally would use wood glue for two sheets of wood. If it is clamped together properly it shouldn't warp during production process.
That's how it seems to me.

Also, the playing characteristics of the blade should be radically altered by grain orientation, so a cross-grain core will be very different from a single sheet, while two aligned sheets will be closer.

As for the other (noncore) layers, I think it is advisable that they are not sharing the same orientation. Not just warping but easy to crack.


Not an expert by any means, but that's my thinking.

P.S. You can just buy some other wood, too. It isn't expensive, is it?

One exception are blades made in the same way as the Stiga Clipper - it uses a core made up of three layers of equal thickness. The middle ply is crosswise. The outer two core plies are lengthwise. There are a ton of blades that use this type of core, typically all the Stiga 7 ply blades (they will swap out the outer plies with hardwoods like ebony or rosewood). Lots from other manufacturers, too.



Iskandar

I figured core was almost by definition one sheet of wood, so shows how much I know.

Anyhow, there are a lot of 'single core' blades - all of the ones in my collection seem to be.
I still think OP doesn't have an issue.

If you think about it.. if you go by two rules: 1) The surface plies have to have lengthwise grain and 2) each subsequent layer has the opposite grain direction, then in all 5 ply blades the center ply HAS to have lengthwise grain, and in all 7 ply blades, the center ply MUST have crosswise grain.

5 Ply: L-W-L-W-L
7 Ply: L-W-L-W-L-W-L

Not exactly germane to the first poster's question, of course - I agree that if he glues two layers of balsa together with the grain in both layers going the same way he's essentially created one double thick ply.

Incidentally, I used to make what amounted to 7 ply blades that violated rule 2 above - there was one thick center balsa ply with grain going lengthwise, and then I used very thin aircraft plywood with the outer plies also going lengthwise. So you had L-W-L-L-L-W-L, with the center layer being thick balsa and the outer six layers being very thin birch. These are the easiest blades to source wood for - any model airplane hobby shop sells balsa and thin birch ply. I also made a few blades with end-grain balsa cores (much like TSP's balsa blades), but that's another story.

Iskandar