Cricket Bats, is it important to understand the willow?

Posted on May 10, 2012 by Andy

Hi all

Is it important to understand the willow? Straight into it I reckon!!!!

Cricket bat willow grain and perform

Lets go over some old ground, why not it is raining afterall…. Ok we know that cricket bats have grains running down the face of the bat and we know the grain itself is the end of year growth, the bark if you like. Well if you didn’t you do now!
So something like this:

Then in between all the grains, the vessels of the willow exist. We know the grain area is denser, so we will see something like this under a microscope.

No need to thank me for the pics. You can now see the grain is dense [here is the link for grains blog http://www.whichcricketbat.com/cricket-bat/cricket-bat-voodoo-willow-and-performance]

Brilliant almost getting to the point

Cricket Bat willow is a natural fibre reinforced composite!

Bear with me here! We know the vessel run through the cricket bat from shoulder to toe. We can see those vessels are layered in the willow itself and mixed with the grain. This longitudinal nature of the willow fibres determine some really important factors in cricket bats. That is, in this vessel orientation and layering we get stiffness, therefore the fibre reinforced composite heading.

So what are you talking about?

Well elasticity and bending frequencies. Due to the vessel layering it affects those aspects of the cricket bat, this leads to cricket bat performance. I wont go to far into this but here is a snippet. They are both intertwined here, elasticity and bending frequencies.

Ok bending modes of the bat, this is based on the bat shape [profile] and if you take into consideration the excitation range [vibration] of a cricket bat based on impact we know you can raise or lower the bending mode frequencies of a bat based on mass of the blade and handles, in layman terms a gain in performance/

But now you can see the willow itself, the vessel layering and the grain effect this as well and why the pressing of the blade is so important as this add another composite layer. Ah I see the composite light turn on didn’t it…

I think as I am just about to finish up here & I’m going to answer my own question!!!!

Yes it is important to understand the willow and not just grab a piece of it and work on it. There is more to look at then just that.

By the way as a quick aside this vessel layering is why Salix Alba Caerulea is used and also the environment in which it has grown in effects these vessels and there layering. Goodbye European willow, Canadian willow, English willow nutured in India and any other rumour you may have heard.

Hope you liked this one

Thanks

Andy

Podshaver and English Willow fan

Cricket bats and SAF hidden innovation?

Posted on April 26, 2012 by Andy

Hi All

I had a long chat and email tennis with a very interesting and well informed chap today about Cricket Bats and I tried to relate hidden innovations in SAF bats to performance. Anyways I thought I’d right something about my bats and stuff you may not necessarily see.

Cricket Bat Balance

You may know it as pickup, that is, “weighs 2lb 12oz pickups like 2lb 8oz” or “Mate, that picks up like a railway sleeper” Whatever it is we are concerned about it! So apart from feel on the back swing what does it do? Well it is actually quite important really in technical terms not the actual back swing but the physical balance of the bat. This and hand position determines the centre of percussion [CoP].

A quick recap CoP results in minimum reaction force at the hands or as I sometimes simplify it to, your hands move neither forward nor backwards when you play a shot.

Additionally CoP is related to hand position, that is, mass and MOI when swinging about the hand pivot point. As I’ve previously said CoP moves that is, it isnt just the bat that control CoP it is combination of the batsman and the bat.

Anyways what I am trying to say what you dont see is that this has been taken into account therefore you see offset edges and spines on most of my profiles to account for that movement. It isn’t just a nice shape the whole swing from backlift to hitting the ball is all taken into consideration on the profile shapes

Cricket bat and ping

The “Sweet spot” isnt that the Centre of Percussion, well I often generalize this because I get asked about “ping” all the time. It is often easier then the longer discussion on this, which I had today by the way!

Sweet spot and or middling area is where the bat absorbs the least amount of vibrational energy during the impact with the ball! Great I hear you say I got that it is the big bit on a bat! Now for the hidden innovation please for sweet spot please?

Vibration on a bat is related to willow selection, pressing techniques, handles and mass distribution. Well not sure I’m innovative here! Maybe just with the pressing and my profiles differ to others [at the moment at least I see a few copying], handles are very good quality and willow selection well everything is handmade by me!

Well I think that is it for now

Thanks

Andy

Podshaver and Yorkshire Tea drinker!

Not a blog as such

Posted on April 11, 2012 by Andy

A bit fun with one of my sons who popped in to see me with my camera phone

He’s eight one of my twin boys and has artistic flair as you will see with his editing

Thanks

Andy

PS: All drawknife work is realtime not speeded up or slowed down!!!! hahaha

PPS: I promise I will do one of those artistic video with the whole process in it soon!!!!!!

Heartwood and Cricket Bat Grading!

Posted on March 27, 2012 by Andy

The much maligned heartwood question…..

What is heartwood?

It is harder and bit more brittle then the sap wood as the moisture is moving out and into the sapwood, the whiter bits in the bat. It will more then likely have more grains if there is heartwood present. Having more grains generally means it will last slightly less time but come to life quick but if you look after them this generally wont happen. Benefits in having heartwood is it is slightly stiffer and lighter due to less moisture so potentially better performance but it is brittle.

What do people think of it!

Some people say have it on the inside edge, some say outside edge it depends which one you hit most, it doesn’t really matter to be honest if you worried about hitting the edge then it is more of a profile shape question then a heartwood on what edge question.

I’m on the stiffer and good performance side of things for heartwood as explained just a minute ago!

Same as any bat if looked after properly it should last it may need just little more extra fussing over, oiling little and often to keep the wood nourished but that can be said for any bat. Then you’ll get the obligatory edge tape and facing but that is again the same for any bat

Some of the stuff written about Heartwood in Cricket bats is absolute bunkem’ by the way!!!!

That brings me neatly on Grading!

What actually is a grade 1 bat, in fact what actually is a grade 1++++++ bat etc etc! For the last bit I dont know, sorry! I do a “Performance Light” I can tell you what that is, it is rare bit of willow that has 11+ grains and is a light cleft.

What do you mean I hear you ask?

In general clefts with lots of grains are heavy as more grains mean they are denser, it is rare that you get light tight grain bat with all sap wood in them then on top of that they need to perform well after pressing. There is nothing more disheartening they get a nice piece of willow that doesn’t want to press well, yes it happens. It could be because the drying wasn’t quite right on them in the yard and moisture has not come out of evenly from the cleft or there is no real elasticity in the blade!

Well that point brings me onto my grading, they are all graded on performance here and a little bit on looks [number of grains]. It doesn’t mean you will get a bat has a load stains in them or horrendous grains, a grade 1 bat may have heartwood in it but see above about that.

Graded on Performance, so what does that mean?

It means they all have the lower elasticity and the upper stiffness that I feel they need to be a grade 1 cricket bat. They have been tested, flicked to measure the tone, hit will a mallet to listen for a crack sound and then had a cricket ball bounced on them. If you buy a cricket bat from me you will often see the odd seam mark or small indentation from a mallet on the face. That is me making sure you have a grade 1 bat and the middle and centre of percussion is where is should be. Anything I feel is not right will lower the grade. Actually a brief note on grade 2 bats, these either have less grains in them and I cant bring myself to sell them as Grade 1 or they will take slightly longer to prepare so they are ready play! Some of the wider grain, ugly-ish bats I have at the moment are absolute blinders!!!!

Thanks

Andy

Partime Blogger and Podshaver

I like this Cricket Bat and want the same bat again!

Posted on March 20, 2012 by Andy

Replicate a Cricket bats feel!!!

Anyways lets take a look at this it might get technical but loads of math involved here so I wont be going to far into it on here……!!!!!

So what makes a bat feel like it does?

Ok you could say swing weight but it isn’t just that! It’s the speed of the bat when playing varying shots and how you hold the bat. Lets remember we are talking about swing feel and hitting areas here!

So this leads onto looking at cricket bats as a combination of things. Lets look at the cricket bat and break it down…. [Please note: I'm disregardinig bat performance here, so don't comment or email me about that]

Deep breath!

The speed of a bat is related to bat weight, the physical bats centre of mass [pivot point], middle position and you!!! Your grip, yep you again, how you hold the bat will determine how the bat rotates for pickup and shot playing. ”What the Deuce” your saying it now….

SO WHAT DOES THAT ALL RELATED TO.

Something has changed, well lets remember willow is organic you may get a bat that looks exactly the same, weighs the same but feels different. All of sudden that nice piece of organically grown willow is pain in the ass because the the centre of mass of the bat has moved or the pivot point rotation down to your grip is slightly askew.. A bat that looks the same isn’t, you can pout a bit here if you like….

IS THAT IT?

Well no not really… Golfers can select clubs so they have matching feel and tennis players with there rackets so why can’t we do it for cricket! Well yep we can! What we need to look at here is Moment of Inertia and some other derivations and a good testing setup!

There you go again about Moment of Inertia, why?

Well it is kind of this, MOI, and a bit more!!! For obvious reason I don’t want to go to far into it…. Ok back to moment of inertia, we need to derive some stuff from the cricket bat that we use. Moment of Inertia will tell us the force required to change the velocity of an object, that is, how hard it is for us to move the cricket bat to hit a ball, this in general terms will give the feel of the cricket bat.

Moment of inertia provides a baseline for us around 2 pivots i.e your grip and physical cricket bat balance. With a bit of dwiddling and some math derivations due to batting speeds we can get you a matching feel for your cricket bat. Sounds easy hey, well it requires the original bat for tests against and like I said a good bit of math and then you need to get a cleft and make a replica bat! Not a CNC machine or sticker-r-us bat company in sight for this

I hope you found that interesting….

Andy
Podshaver and Coffee Drinker!

So why the Hades

Posted on February 21, 2012 by Andy

Ah the Hades

Can I just start by saying it is probably one of the best bat shapes I’ve ever decided to make in a pure theoretical to practical sense, it is engineering geekdom . The bat is me, it is traditional in the respect that it is completely handmade, the edges aren’t huge, they dont have to be. I drew a leaf out the SAF Fabrica book for that one, now the SAF Origin. It has the balance of the SAF Infinity a bat born from T20 but with no gimmicks. I took another leaf out of the golf & tennis handbook and because it is handmade the weight versus the swing weight feel is superb.

It is innovative because it has been designed from the bottom up. Literally, I started at the toe and balanced the cricket bat from there. It brings into play the engineering techie areas of the a bat that combine to make a great bat…. Actually time for a picture…

Offset Edges

What is an offset edge? Hmmmm take a look at these two types of profiles

Normal Edge vs Offset Edge

So what have I done, well in simple terms I’ve shifted the willow lower into the toe area and moved the spine higher. Now I’ve got more willow towards the toe section the same willow in the middle section and less on the edge further up. Balance isnt effected because the spine is slightly higher.

Great! So what does it do

Basically I’ve extended the middle at no cost, it has great swing weight due to the mass lower down, balance/pickup is good because I raised the spine because off the willow on the edge. In the back ground I’ve moved the centre of percussion into the hitting middle area so your sweet spot is where you need it when you swing at varying speeds i.e where there the willow mass is. By creating a less uniform area of willow mass I have meat in a larger area resulting in more value for your shots as well. All this combined is part of the coefficient of restitution as well , I didn’t forgot about that!

Another pic!

Hades Offset Edge - click to enlarge

Also the pressing on the Hades is slightly different, it is based on a sound type to ensure I get the right pressing [therefore part of the coefficient of restitution] where all that willow mass is but that stuff is a bit more complex so I’ll leave that for the time being

Also it will be good to say at this point I dont just throw the edge in lower and raise the spine it is will be placed slightly differently on all the cricket bats made. I’m still yet to find two bits of willow the same and a standard robot of a batsman :-) This cricket bat defiantly isn’t a one trick pony

Thanks

Andy

Mass Moment of Inertia and Cricket Bats!

Posted on February 16, 2012 by Andy

Hello again! I’m loving the title of this one, “I cant wait I hear you say..” [No pics sorry]

Replicate a cricket bats feel [Or your heading....] My Favourite Cricket Bat!!!!

If you’ve been playing cricket for a while you have more then likely had a favourite bat. Then you’ve bought a bat with the same middle position, same weight, same manufacturer and it’s just not been the same. This intrigued me a few years ago so I took like through my geeking cricket bat techie glasses!!! It ended up being a heck of question and a half mainly due to the maths involved!!!!!

So what makes a Cricket bat feel like it does?

Speed of bat is related to bat weight, the physical bats centre of mass [pivot point], middle position and you
Your grip, yep you again, how you hold the bat will determine how the bat rotates for pickup and shot playing. [swing]

So what does that all related to here, I see you asking….

Something has changed, well lets remember willow is organic you may get a bat that looks exactly the same, weighs the same but feels different. All of sudden that nice piece of organically grown willow is pain in the arse because the the centre of mass of the bat has moved or the pivot point rotation down to your grip is slightly askew.. A bat that looks the same isn’t, you can pout a bit here if you like….

Is that it you just confused me?

Mass Moment of Inertia BUT why?

Well it is kind of this and a bit more, for obivious I don’t want to go to far into it…. Ok back to mass moment of inertia [MMOI], we need to derive some stuff from the cricket bat that we use.

Well mass moment of inertia will tell us the force required to change the velocity of an object, that is, how hard it is for us to move the cricket bat to hit a ball, this in general terms will give the feel of the cricket bat.

Moment of inertia provides a baseline for us around 2 pivots i.e your grip and physical cricket bat. With a bit of dwiddling and some math derivations due to batting speeds we can get you a matching feel for your cricket bat. Sounds easy hey, well it requires the original bat for tests against and like I said a good bit of math and then you need to get a cleft and make a replica bat!!!!!

A great example of this, MMOI, you’ve probably seen

Where has my Cricket Bats middle gone!

We love fiddling with bats so the next heading is, bear with me here please

Pick up of a Cricket bat and adding a grip or weights to the handle

Ok you’ve added a grip or some sort of weight to the handle because the cricket bat you have bought picks up like a railway sleeper. The cricket bat feels better with regards to picking up but all of a sudden you’re getting bat vibration from the where the middle was.

The techie bit, only a little bit!

The point at which you get the least vibration from the bat is called the centre of percussion [COP]. I think I’ve discussed this before so take a look at another article for the infomation on this.

Hmmmm, by adding weight, e.g. an extra grip, you move the centre of mass or the balance point of the cricket bat towards the handle and this moves the COP [the point of least vibration]. That is because the centre of percussion is related to the total mass of the cricket bat, the balance point and the mass moment of inertia…..

So what does that mean?

The cricket bat picks up better but all of sudden the middle feels like it has shifted by about an inch all because of the extra weight at the handle end! Holy heck!!!

Another one to put in the back of you mind, a bit more techie but I hope you find it interesting and makes you think a bit more of that piece of willow you wielding about

Thanks

Andy

https://twitter.com/#!/AndyPodshaver

Cricket Bat voodoo, willow and performance

Posted on February 7, 2012 by Andy

Willow and grains

Older trees are more stable but not as strong as middle-aged trees. Younger trees move more and are not ready to use. Tighter grain is what some people prefer, but the grain can be too tight because it will start to lose strength at some point.

As trees grow through the season, growing season that is not the cricket season, they grow faster from spring through summer and more slowly from autumn through to winter. That is what we see in tree rings, sap wood and then grain, then sap wood.

Tighter grain means less space in fast-growing fibre. This space in looser grain is where the moisture stays, which is why a tighter grain is more stable [stiffer] than looser grain but density is also heavier in tighter grain. The increased density means that the wood is stronger therefore it potentially makes a bat come to life quicker but it may die earlier because there is no glue, sap, in the grain itself.

Cricket Bat Willow Grains

Heartwood is just wood that has lost its sap as it moves out through growth therefore brittle, it is also denser.

The Give and take bit

Ok loads of grains brilliant hmmm is it, if you look at it on density perspective then we now know tighter grains will make for stiffers blades but it may also mean faults develop quickly. Dont mind I hear you say, it also means, more weight for the same given volume. Performance of cricket bats is related to a number of things and wood mass in the hitting area is one of them. Ah ha! the give and take bit.

Anyway, pressing a tighter grain cleft as opposed to looser grain cleft will be different which was one of reasons I wrote that bit, I hope you can see why now!

That brings me neatly on to!

Knocking in a cricket bat

When a bat is pressed it creates a stiff surface layer on the face of the bat. If you press it hard the willow fibre’s combine together too deeply into the wood and the blade has no real rebound [ping] If it is to soft then lots and lots gentle hammering and then more rigourous knocking in is required to stiffen up the blade. A quick example [you can work out soft pressing ]

Cricket Bat pressing

At the end of the day we all hope that we don’t get an over pressed bat and then the basic idea is to stiffen the surface

Knocking in a Cricket Bat

On the left side is surface stiffness along the bottom is hours spent knocking in.
Look at the dot shape and 0hrs of knocking in and then at 4 hours. The surface stiffness has doubled!!!!
So what has happened, the core of the bat is left unhardened resulting in a more elastic response of the bat. Because the surface is stiffer less enery will be absorbed by the bat and so therefore it will be transfered to the ball

Whilsts I have Mr Issac Netwon mentioned on the x-axis on the graph, something brief on performance!

Newtons Law!

As you probably know from phyiscs for every action there is an equal and opposite reaction, also energy cannot be created or destroyed it can only be transfered, transformed, converted from one form to another.

The upshot is though, as you can all probably guess, is to transfer as much of the energy you are exerting to swing the bat to the ball and conserve as much of the energy of the bowled ball speed. A real life example is hotspot. We’ve all seen hotspot that is energy loss due to heat from the cricket ball hitting the cricket bat

Cricket Bat performance options!

There is the option of having increased stiffness, a bat that doesn’t absorb the energy of bowled ball. So for example the bowler transfers his energy to the ball and bat transfers it back. Well that is the idea If the cricket bat vibrates as we know it does on impact it absorbs some of the energy. Therefore the less vibration of the bat the less energy absorbtion and the greater the energy transfer.

Cricket Bat Vibration

There is the option of having an elastic bat. A bat that has the ability to hold the ball in the hitting area so the bat vibrates far enough through a cycle so it acts as a trampoline. Basically vibrations are wave’s in simple terms if the ball can be held at the point of impact for the time it takes the wave to go down on impact and then back up again. There is effecitivly a rebound effect. This effectively is a bit of a non starter though as the the time required to hold the ball in the vibration cycle position is too long.

Cricket Bat Trampoline Effect

There is swing weight, bat mass, density in the hitting area. It all gets a bit techie…

Believe it or not cricket bat handles make a difference

Then there is the player holding the bat and what he is comfortable with and what makes him confident. What you need to do is speak with a Bat Maker and tell him how you play and he should point you in the right direction.

Andy
Podshaver for San Andreas Fault Cricket Bats

Cricket Bats, Edges, Concaving, myths, smoke and mirrors!

Posted on February 2, 2012 by Andy

Thought I’d get one done as I will more then likely be out of the blogging loop for a while. Please note this is assuming that the cleft start weights are the same, which they generally are if you making a bat to target weight.

We eat with our eyes

Do you buy cricket bats with your eyes, is the first thing you say when you see a bat, “Look at the size of those edges” and do you hear “40mm edges, oh and it only weights 2lb 8oz” in reply from its proud owner, phenomenal, well is it!

Stuck now, where do I go for the next bit, smoke and mirrors, myths or concaving. Hold on I have a plan….

Smoke and mirrors, myths and traditional vs concaving

See what I did there

Traditional vs concaving

I won’t say this is the age old question as it is fairly new to the world of cricket in the scheme of things but a question often asked nowadays. Concaving gives you a big edge and traditional doesnt, eating with your eyes again. So what the difference, a quick diagram below.

Cricket Bats Edges Traditional vs Concaved

I suppose you are wondering what that is? Well you should just be able to make out the two styles of cricket bats. What I’ve done is draw some lines joining the two at various heights to show you where the traditional bat would have the same size edges as the concaved bat and where the concaved bat would have the same size edge as the traditional bat. You have to imagine that you are shaving either of them along the edge so the edges match in size.

Ok on the bottom you have the amount of willow behind the face based on its edge size, so for example the concaved bat has a larger width for the orange section then the traditional bat. Then you look at the traditional bat you’ll see the middle the red bit is larger then the concaved bat, the pink bit.

Now if you read that and understood what I trying to say you have probably guessed the next bit. If I concave a bat I get a better edge. Cue another picture

Cricket Bats Edges

On the traditional bat the orange to green bit shows where it lags behind the concaved bat, oh and I stuck a dirty great box around it Not much hey in the scheme things, you are suppose to be using the middle afterall

So when does the traditional bat start making a name for itself! Cue another one of my special diagrams.

Cricket bat Traditional vs Concaved

You wont think I was a qualified Mechanical Engineer with these wonderous technical drawings Oh dear concaving isnt fairing well, we’ve got more willow over a large surface area on the traditional bat and as we know Force = mass x acceleration

Below is a close up view, seems the middle – middle [red and pink bits] is over a larger area on the traditional bat as well

Large edge = Good bat, myth

So what do you reckon of the that 40mm edged bat now, it is food for thought isnt it! Don’t assume that a traditional profile isn’t good because the edge size is small, it will pack some punch.

smoke and mirrors

Ok flat faced bats, a flat bat instead of curve gives the impression of a larger edge!

Pressing differences

I know the flat one is a bit extreme but you get the idea, if you edge a ball it will compress to something similar to the curved faced bat plus you have to knock the edge in, that square edge will to a certain extent sooner rather then later resemble the curved face bat and at least the curve face was pressed to be like that so it shouldn’t of cracked up in the process, smoke and mirrors to give you a big edge?

Also as we know you could shave the edge down a bit from 4.25 inches to something less, Please note this is also done intentionally on some bats not just smoke a mirrors. Then the unscrupulous over dried willow technique, lets make a normal cleft light by taking the moisture out of it. [http://www.safbats.co.uk/BAT-BLOG/cricket-bat/cricket-bats-and-moisture-content]

I think I’ll stop there… on a final please note, this is intended to make you aware of the potential differences between bats and give you a respect for each shape. There are always merits to shapes if you understand the what and why about them. I make both types, traditional and concaved but as with all my bats I understand them they aren’t one dimensional. If I had to make a bat that was ring fenced I’d give it all up.

Thanks All

Andy

Bat Maker / Podshaver originally from Devon

Cricket Bats and Moisture Content

Posted on February 2, 2012 by Andy

Hello

Anyways I’ve been asked a few times, what the heck is all this about moisture content of a cricket bat?

Well this one isn’t to complicated so no real need to hold onto your hats for this article!

Cricket bats and Moisture

There are a couple of schools of thought with regards to what level of moisture content should be left in the willow cleft when it is ready for the market! The variation is around 2% and that is either 10% or 12%, I won’t go into who is right and whose wrong in my opinion as I don’t really have an opinion on it. Yeah right I hear you say! Well maybe you are right but as I’m going to explain a bit about it you can form your own views on it!

Here we go, the measure of resistance to elastic deformation!

Having the willow at a certain moisture means the willow cleft has certain characteristics. Oh please I hear you say this was going to simple…. Ok let me get this done quickly then! Young Modulus there you go done, well almost! Elasticity is what I’m talking about and as you probably remember from your Physics lessons about Youngs Modulus / Hookes Law.

Ok, why 12% well it is effectively a standard for timber yards, but I must say I wish some willow merchants used this, I’ve had to create my own room to take mine down to that level. I forgive them though as they always look after me. Ok I went off on a tangent, within the moisture range specified above the elasticity of the willow will be in a range that is known quantity 5.3 N/mm²[normal caveats apply for an organic bit of wood] This means you’ll get a cricket bat that should have the bending properties that have been around for years.

Bending! excellent that brings me onto bending strength. Ah the light bulb moment “I see it is related to elasticity.” Yep, it is as you’ve probably worked out the less elastic the willow is the less bendable it is!

As the heading said the measure of resistance to elastic deformation, brilliant…..

Why, are doing this to me, what does that all mean for my cricket bat?

It means that the less moisture content a cricket bat has the stiffer it will be, great I’ve read some your other articles and stiffness is good.

Yep it is but it is at a cost!!!!!

Why, because the life of the bat is reduced because you have what in effect is a brittle bat. Yep you have a bigger bat as less moisture means a lighter cleft and yep you have a bat that better goes from the outset but it will die alot quicker possibly only giving you only a few hundred runs! [This includes nets as sometimes people forget about there net sessions] So it is better to get that stiffness through the bat makers ability in making and pressing a cleft then artificially from over dried willow to make it look big

Well there you go, I hope you found that one useful

Andy
Podshaver for San Andreas Fault Cricket Bats