Tag: Bergerault

-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 (part 2) (Job No: 1239)

All the metal work needed to stop this Bergerault pedal glock collapsing at every inopportune moment was made in 1239 Bergerault pedal glock (pt 1).

I have a few golden rules when it comes to making and repairing percussion instruments, for instance it has to sound good, work, last, etc. In application I also have considerations to make and using experience I identify and remove potential problems before they happen.

This glockenspiel has two examples, first on the list are rattles.  Has it not dawned on the manufacturers that percussion instruments are played by hitting them, and that due to their very nature of being musical instruments they vibrate.  So anything that can work loose and vibrate will do.  Why on earth then would you choose to use a buckle on a percussion instrument?

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Needless to say, they go in the bin!

The next problem is the damper pedal which just hangs off the end of the connecting rod.  Of course this is fine if the instrument never moves and of course the world has a perfectly flat uniform surface.  The damper bar is sprung, so any movement on the instrument will cause movement in the springs – they bounce.  Low and behold the pedal becomes detached, bits snap off, get bent….

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It is only because I am also a quantum physicist as well as an instrument maker, who does a bit of neuro surgery on the side, that I am capable of coming up with solutions to these problems.  Webbing loops instead of buckles, and I remake the pedal connector with bigger sides so the pull rod cannot come off (which is fine if the instrument always stays set up). 

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With those bits of idiocy resolved, the instrument can be assembled and finished.

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Bergerault Pedal Glock (part 1) (Job No: 1239)

There is a big problem with the Bergerault pedal glock; it falls apart if you move it. Besides from being highly irritating, this self destructive characteristic also causes things to break, fall off and get lost. This is a shame, because the instrument sounds nice.  So what happens is that they get sent to me to be sorted out!

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In explanation of what the problem is I’ll use an analogy with our old friend Paul the Porter:

Paul the Porter is playing on the see saw, in the park with Preschool Paul.  When the two Paul’s are sat at either end, Preschool Paul gets flung high into the air which he loves.

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After a little while Paul the Porter’s nerves have been sufficiently jangled so he moves towards the centre.  Preschool Paul is amazed that they now balance and he begins to understand the mechanical principles of leverage.

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So returning to our glockenspiel and looking at the base of the instrument, it is immediately apparent (to me) that there are serious design flaws which mean that there will always be problems with this instrument falling over.  Thus the Bergerault Pedal Glockenspiel appears in my top ten bad designs, which includes a detailed explanation of what is happening.

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In brief, the picture above shows the main offender – the bottom bar has an adjustment on it to alter its length.  This facilitates removing it from the glockenspiel when it is being folded down, but also now means that the legs are not fixed at the bottom.  So when the glock is being wheeled along, this bottom bar offers no structural support.  Returning to our analogy of the see saw,  looking from directly above, the two wheels move about this point like a see saw, compressing the adjustment shorter so it actually falls off immediately prior to the instrument collapsing!

My solution, which applies to just about every instrument I look at, is to sort out the very bottom of the instrument.  It is only when the four wheels are fixed firmly in place that there is any hope for the rest of the instrument to be stable. 

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A large part of the job is getting the attachment of the new frame to the existing working well.  All of my designs keep the number of wing nuts for the player to remove to the absolute minimum; I spend time making it properly to save my customers time every time they set the instrument up.

In the first picture the screw is soldered in place so that it cannot rattle loose and fall off.  The second photo shows the screw and a bolt holding the metal in place.  In this instance I have used two points of contact (usually I have three) so that the see saw effect cannot occur.  The third picture shows the cutout around the peg onto which the pedal arm will rotate; the cut out enables the subframe to be lifted off the glockenspiel.

Once both ends are complete they can be joined together with a bar of fixed length.  The two legs cannot now move apart, but the entire strength is still reliant on the welded joint in the centre, and the screws holding the frame onto the glock.  One of the reasons why I extend the connection to the transom as wide as possible is so that I can triangulate between the two points, and therefore massively increase the strength of the frame.

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Bergerault have already got diagonals from the note bed to the legs, but because the instrument is height adjustable they come down from the top to ensure that the uprights (theoretically) remain parallel.  However they have built a castle on sand, like all the manufacturers (and me) instruments are designed from the top down, but I build instruments from the ground up making sure that the foundations are solid.  Therefore I make sure that the uprights are triangulated to the (now) solid base frame.

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With all the metal work complete, I can send the frame to the powder coaters and resolve the other problems which irritate the customer in 1239: Bergerault pedal glock (pt2)

Bergerault Vibraphone (part 4) (Job No: 1214)

This post continues on from 1214: Bergerault vibe (part 3) and started with 1214: Bergerault vibe (part 1)

The inner two note rails are only supported at the high end of the vibraphone by a metal bracket.  Onto this bracket is also mounted the motor.
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Because I have increased the depth of the two outer rails this bracket no longer fits.
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So I just modified the design a little, and welded new outer supports in.  Now it will also be stronger, and certainly welding is a lot stronger than brazing which is how Bergerault make their instruments.  Welding is fusing two like metals together, so essentially it becomes one piece, whereas brazing uses a different metal to join the two elements, like glueing them together.
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Now this bracket is on, the top frame is rigid, all it needs is the motor unit.  Then I can put the legs on the vibe, and put the notes back on.
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It’s both satisfying and dissatisfying to see it all finished.  On the one hand it is good to see a finished instrument, especially when the job has been so involved.  On the other hand it looks just the same as it did when it came in, which is the point, but still I can’t really see any evidence of all the work I have done.

Bergerault Vibraphone (part 3) (Job No: 1214)

This post continues on from 1214 Bergerault vibe (part 2) and starts with
1214: Bergerault vibe (part 1)

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The above image shows my progress with the Bergerault vibraphone over the last three days, from the left; prime, undercoat, top coat.

This is the moment, before I put the new note rails into the instrument, to sort out any problems with the inner two note rails.

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Unsurprisingly, these rails were also loose.  Like the original outer rails, these also have a single tenon towards upper side of the rail.  This is supplement with a tiny bracket at the bottom.

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As Paul the Porter pushes the instrument at the top, there is greater friction at the wheels making the instrument rock from side to side.  The leverage exerted by the very long rails on four octave instruments is enough to break open a single tenon joint, especially if it is located at either end (top or bottom).  Again this is a design flaw; a demonstration of a lack of knowledge, forethought, and expertise.
I go to museums and see objects made literally hundreds of years ago that demonstrate the type of joint needed to resist a particular force.

Once the glue is dry on the inner note rails, I can then glue in the outer rails.

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If you look very closely at this end of the outer note rails, there are two holes.  This is an idea that I ripped off those museum pieces.  It’s called a pegged tenon joint.  Back in the day, they would have used a wooden peg, today I use a big screw.  This screw ensures that the tenon cannot be pulled out, and massively increases the strength of the joint – why wouldn’t I do it, it took less than five minutes.

At the end of the day, I will remove the clamps and do one final coat of paint so that it will be finished for the final assembly.

This post continues in 1214: Bergerault vibe (part 4)

Bergerault Vibraphone (part 2) (Job No: 1214)

This post continues on from 1214: bergerault vibraphone (part 1)

The timber I bought is European Oak.  I could have also used Ash, but that was not available.  Both are known for their structural rigidity as opposed to the original timber, which is hidden behind a plastic veneer, but looks to be African Mahogany which is a cheap easy to use timber, which is not known for its strength.

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After planing the timbers to size, I marked off the length and angles, to duplicate the existing note rails.

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Because I am doubling the depth of the note rail, I put a double tennon at the ends to go into the end boards.  This will massively increase the overall strength of the instrument.  These outer rails are the only joints that hold the whole instrument together, so they must be good (unlike how they were).

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Pictured above are the note rails with double tennons roughed out ready for the mortices to be dug.

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Once All the new mortices were dug, I ended the day with a dry assembly to expose any problems.

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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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Bergerault Vibraphone (part 1) (Job No: 1214)

These Bergerault four octave vibraphones are massive!  Even though vibe notes are made from aluminium, that doesn’t make them light, in fact the opposite is the case.  Percussion instruments are heavy, but vibraphones are particularly so.

The reason for this vibraphone coming into my workshop was because the butterflies in the resonators were hitting the underside of the note bars.  When I went to collect it, I spotted the probably cause, and verified it with my straight edge once back at base.

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Because the vibraphone is so big, it is hard to get it all in the photo and still see the issue when the notes are on, but after I have removed the notes it can be clearly seen that the instrument sags in the middle.

The first job is to remove the base frame, which are attached to the end boards.  It was at this stage that I noticed another potential problem:

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The little blocks that Bergerault have put in to hold the resonators, are wonky.  I will have to investigate this, because I also noticed that the resonators didn’t hang straight, they were pulled in at the bottom.  I suspect that this is a Bergerault design error, but it just seemed wrong to me.

Once the legs are off, I can now remove the High End board using the motor support bracket to hold the note rails.
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Next the motor and control unit are removed.  I will take the opportunity to improve this whole area which at the moment looks like a dogs dinner.

Finally the offending rails can now be removed from the Low End Board.  Classic understatement, I had to sit down and take a breather after I finally got them out!
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Now I am ready to make some replacement rails – time to go shopping for timber.

The story continues in 1214: Bergerault vibraphone (part 2)

Bergerault Xylophone Tuning (Job No: 1059)

Due to the use of hard beaters, xylophones are prone to face and edge damage.
Whilst it is easy to see the wood splintering at the edges, damage to the face is harder to see, but both will reduce resonance, and of course affect the tuning.
Vibrations don’t only travel along the length of a note bar, but also across the width and through the depth. The grain of the wood runs up the length of the bar. Below is an example of the cellular structure of hardwood:
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In general the cells are lying like long strings of sausages alongside each other, stuck together with cellulite. Vibrations go along the length very easily, but meet more resistance going across the strings of cells. A crack creates a void that the vibrations cannot cross. So depending on where the crack is will determine whether anything can be done.
Glueing the pieces back together is not practical, but also will not solve the problem. A crack through the entire depth of the note means a new note, any repair will be temporary – the wood will always be trying to get to a relaxed state, glueing and clamping is stressing it.

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So the only option is to remove any loose wood that is dampening the sound. As it is removed, the improvement in resonance can be clearly heard. It looks drastic, but the note is useless as it was, and repair is cheaper than making a new note.
The photo shows that the left hand edge has been cleaned up, but the note still didn’t sound, so the face was examined, and a crack discovered. That groove in the face is about 3mm deep.