Tag: bad

-1. Rock, roll and twist again?

This post is part of My top ten bad designs series of posts.

Percussion instruments are three dimensional objects, so in order to effectively describe what I am looking at when I see design problems, below is a diagram of the three axis on which measurements are made.

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The X direction of movement is forwards and backwards.  The Y direction is left and right.  The Z direction is up and down.

However musical instruments don’t just exist on paper, they are used in the real world, and thus are subjected to forces that are also three dimensional.

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These forces are called Roll, Pitch and Yaw.  They are measured in degrees around their respective axis, and I have colour coded them for clarity.  For example, Roll (in green) occurs when an instrument wobbles front to back, it is measured in around the Z axis.  Pitch is one that wobbles side to side.  Yaw is an instrument that has a note bed that rotates when viewed from directly above.  In this post I am looking at roll.

Paul the Porter, and Preschool Paul are going down to the park.  As they approach the see saw, they notice that it is balanced horizontally on its base.

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Preschool Paul loves the see saw, he knows all about how, when on side goes up, the other side goes down because it is only fixed in the middle.  Now imagine that the see saw is the low end of an instrument; as the naturals go down, the accidentals go up.  This is roll. 

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Oops!  And here it is, our first example of bad design – a Bergerault Pedal Glock with a central leg at either end.  Just like the see saw above!  Now glockenspiels may not be very wide at the low end, but they are wide enough, and certainly heavy enough for this central leg to be a weak link in the design.  Consider also that it is a “pedal” glock, so there is the additional problem of moving parts within the damping mechanism that need to operate efficiently.  In my professional opinion I give this instrument no chance of surviving for the long term.

Even Preschool Paul knows that standing on one leg is a recipe for disaster.  Instead he stands with his legs spread wide whilst holding his heavy school bag above his head.

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Now this as we all know is solid and stable, and on paper looks like the perfect solution to roll.  However, if Preschool Paul removes his shoes and stands on a polished floor…

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With socks sliding along a polished floor, his feet slide apart.  Substitute the feet for wheels, and make the centre of the X the weakest part…

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Oh look, we have an Adams marimba using a design that is featured on just about every one of their instruments.  A design that is fundamentally floored in concept and the end result is hundreds of instruments all over the place that suffer from dreadful roll issues.  What is more, because the same components are used on all of their instruments, the bigger the instrument, the bigger the problem.

Bergerault use a capital I as the basis of their design – I for inadequate.  Adams use an X for exceptionally bad.  Any instrument design that transfers the weight of an instrument directly through its centre line is always going to be exceptionally bad and the resultant instrument is going to be inadequate to withstand the forces applied.

So what is the solution to preventing roll?  For me, simple is best, and the simplest solution is a square.  The only decision is either solid or hollow.

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The problem with a solid end, like the Deagan Arora (above) is weight, so I mainly go with a hollow square, ie, two legs, the bottom transom with the casters attached, and the top defined by the note bed.  In order to maximise stability, I make the legs as wide as possible, even splaying the legs out at the narrow end to make a trapezium.

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In the next part of this series I will look at pitch, which is when the instrument rocks from side to side.

Bergerault Pedal Glock (Job No: 1202)

Bergerault have secured a place in my top ten bad designs with this pedal glockenspiel.  In order to minimise the number of removable parts and create a glock that is really quick and easy to assemble, they have this “great” idea of being able to adjust the length of the pedal.
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In itself this is a stupid thing to do, but they were forced to do so in order to make the rest of the design work.

The problem is that the legs fold out, and are secured in place first (albeit with diagonal braces that are also badly designed), and then the bottom bar is put in afterwards.  The bottom bar sits on little pins at either ends to enable it to rotate and thus becomes the pedal.  These pins are the problem, the bar has to be reduced in length to get it over,  then lengthened to “secure” it in place.

As a finishing touch, the method of holding the bottom/pedal bar at its full length is a throw back to the 1970’s, a wing screw and a nut.  I remember when certain makes of cymbal stand first started using nylon inserts, now they all do and with good reason as any percussionist will agree, finally something that consistently works.

The end result of all these stupefyingly bad design errors is an instrument that collapses as it is being wheeled about.

The next problem on the list are the connecting rods to the damper mechanism.  At the bottom they hook over little nylon wheels on the pedal.

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These just become detached while you wheel it about making an irritating noise and becoming hooked on things and being bent, except when they don’t become detached and then get bent when the instrument collapses.

The real problem with these rods is at the other end, where a leather belt is used to connect them to the damper bar.

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Yes that is a leather belt.  The photo is actually off another instrument.  This glock had a variety of materials including string, gaffa tape and cable ties.  Leather needs to be cared for, otherwise it dries out and degrades.  The buckles just rattle.

There are a lot more design issues with this glockenspiel, but those three were the problems on this instrument.  However it is not all bad, the notes do sound really good, and after all that is the most important part of an instrument.  It is just a shame that the rest of it is, well, basically shit.

So what did I do?  In reverse order: 
I took the damper mechanism out and sewed two webbing loops to replace the missing leather straps, and eliminate the rattling buckles.  There is no need for the length of these loops to be adjustable, and the webbing won’t degrade as quickly (3 years to 30+ years).

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One of the nylon wheels on the damper pedal was missing, so I made two new ones that prevent the connecting rods from coming off.  This instrument is never folded down.

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I made an additional bottom bar that fits behind the pedal bar.  This secures the legs in one position; they can neither be pushed in or pulled outwards.

Finally I put on better castors.
 

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My top ten bad designs

So many instruments are let down by really badly designed elements.  They are so bad it’s shocking, but this is why I am in business, my goals are to seek and gain an understanding of the root cause of why an instrument broke in order to design a solution that works.

To me, designing is a procedure, not an act. My idea of designing something, is to encounter and solve as many potential problems whilst doing drawings on paper.  It is the way I was taught at school, and it’s a good idea, paper and pencils are cheap, and it saves a lot of time and heartache during the manufacturing process. Designing is not simply a case of, this is the solution in my head, and now it has to be drawn on paper before it can be made. That is just a waste of time and paper.

Therefore the reason why these instruments are listed as being bad designs, is not because I think that the instruments are rubbish, the opposite is often true, as an instrument they are actually sometimes very good, just badly let down by the frame, etc. What I see is a lack of discernment at the very heart of the process of producing an instrument, which is not an attribute expected or desired in a luthier. Mistakes can be forgiven, but ignorance cannot, not when they profess to be professionals.

The writing of thess blog posts will take some time. The instruments I have in mind need to come in to be repaired, so that I can photograph them and explain my reasoning. However, as you would expect, this does happen quite frequently for the most common instruments.

One final point, before I begin; the instruments are not organised into any particular order of inadequacy. They are used to help structure the text in order to highlight the processes I go through when thinking about solutions to problems. Part -1: Rock Roll and twist again looks at the forces exerted on instruments.