Questions about building blades

hipnotic · Aug 30, 2018

I've started making my own blades. So far i made 2, but they are still missing the handles. That got me thinking on a few things. Has anyone tried these?

1. Making the same blade but with different handle length, or even handles with different lengths on the same blade? Would this work as a way to fine-tune the flex of the blade?

2. I don't have access to a lot of woods. Besides balsa, most will be too heavy to use as a core wood. Maybe hollowing out the core in a honeycomb pattern will maintain the structure stability while loosing a few grams?

3. This one probably isn't ITTF legal but it would still make a fun experiment. I'm thinking of using a mixed core, like a strip of wood between 2 balsa wings or something like that. The goal is to have a light core but not so stiff as full balsa core.

EvilOctopus · Aug 30, 2018

not built any blades but i think theres no rules regarding the core having to be made of a single piece of wood or anything. In fact i think theres a donic blade that has a layer of carbon in the center of the core.

hipnotic · Aug 30, 2018

I'm not sure but I think that the rules state that the ply should be homogeneous.

perham · Aug 30, 2018

While we’re at it, why isn’t there a blade with a metal layer? Something like titanium?

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mart1nandersson · Aug 30, 2018

perham said:
While we’re at it, why isn’t there a blade with a metal layer? Something like titanium?

Google "Stiga Titanium"

perham · Aug 30, 2018

mart1nandersson said:
Google "Stiga Titanium"

Wow! that looks cool. Too bad I've already settled on the bat. Where was this when I was EJing?

I wonder why it's not so widespread? maybe the lack of control?

cfagyal · Aug 31, 2018

The only rule for ITTF for blade composition is they must be at least 85% wood. Rule 2.4.2 in the ITTF handbook for 2017 states: At least 85% of the blade by thickness shall be of natural wood; an adhesivelayer within the blade may be reinforced with fibrous material such as carbonfibre, glass fibre or compressed paper, but shall not be thicker than 7.5% ofthe total thickness or 0.35mm, whichever is the smaller

Rule 2.4.1 regarding weight, etc states: The racket may be of any size, shape or weight but the blade shall be flat andrigid.

hipnotic · Aug 31, 2018

"2.4.5 The blade, any layer within the blade and any layer of covering material oradhesive on a side used for striking the ball shall be continuous and of eventhickness."

Ok, they say continuous not homogeneous, i don't quite get what they mean by that.

However, this was not the purpose of the post, i just wanted to know if someone had tried any of these ideas and what were their results.

cfagyal · Aug 31, 2018

I Think by continuous they would mean you can't have gaps. It is common practice for commercial blade makers to have seams in their layers rather than using jointless veneers. Some manufacturers actually advertise that a jointless veneer blade is something "special". So having a multi-veneer layer made up of different types of veneer would be acceptable if it is of even thickness. However i'm currently unable to determine what the benefit would be? What sort of effects are you thinking might occur by doing this? Your last statement in your original post confuses me, as I don't associate Balsa with being "stiff" as Balsa is, by far, the most flexible material used in any blades for a core material. According to Wood-database.com, sorting all woods listed on the website by elasticity of modulus, there is no wood in the world that is more flexible than Balsa, so by adding other woods in strips along with Balsa, you'd be increasing stiffness, not decreasing it.

To answer your question though, I have not tried such a thing. I have used jointed veneers when necessary, but always they were of the same wood.

hipnotic · Aug 31, 2018

cfagyal said:
I Think by continuous they would mean you can't have gaps. It is common practice for commercial blade makers to have seams in their layers rather than using jointless veneers. Some manufacturers actually advertise that a jointless veneer blade is something "special". So having a multi-veneer layer made up of different types of veneer would be acceptable if it is of even thickness. However i'm currently unable to determine what the benefit would be? What sort of effects are you thinking might occur by doing this? Your last statement in your original post confuses me, as I don't associate Balsa with being "stiff" as Balsa is, by far, the most flexible material used in any blades for a core material. According to Wood-database.com, sorting all woods listed on the website by elasticity of modulus, there is no wood in the world that is more flexible than Balsa, so by adding other woods in strips along with Balsa, you'd be increasing stiffness, not decreasing it.

To answer your question though, I have not tried such a thing. I have used jointed veneers when necessary, but always they were of the same wood.

Ok, if gaps are not legal then the hollowed core would be illegal. However, i might experiment with that to see the results.

Yes, balsa is not very stiff when comparing to other woods but it's very stiff comparing to it's self weight. If the core is thin the blade will be slow, if the core is thick it will have that "dead" feeling. By mixing woods in the core i was hoping to have a relatively thin and light core but not a slow blade.

cfagyal · Aug 31, 2018

Yea a hollowed out core would be illegal based on the ITTF handbook, I agree. I never considered comparing elasticity of modulus as compared to a woods weigfht. That's very interesting. What sort of math are you looking at when you do that comparison (basically, if I look at any core, how would I make these determinations? Are there specific ratios you look at that?). I have a variety of core materials and each of them are a variety of thicknesses (for example, I have 3.3, 3.6, and 4mm kiri cores, and the same with Western Red Cedar).

hipnotic · Aug 31, 2018

That's the Specific modulus, which is a materials property consisting of the elastic modulus per mass density of a material. If you compare the specific modulus of balsa with, per example Kiri, you will see that it is much larger. But there are factors to consider, wood is an heterogeneous material and the Young modulus will be different in every direction (x,y,z). Balsa is only strong along the grain, the wood database only gives the longitudinal modulus, the others will be much smaller.

cfagyal · Aug 31, 2018

Wow very interesting. There is much more research it looks like I need to do. Thank you for the insight!

hipnotic · Aug 31, 2018

You're welcome

Questions about building blades

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