Tag: 1260

Premier 701 Vibe damper (part 2) (Job No: 1260)

In 1260 (pt1), I looked at all the work I had to do before I could even start looking at the reason why this Premier 701 vibraphone had come in to be repaired.

wpid-img_20150428_155950.jpg

Having fixed all the issues with the frame and therefore I have an instrument that doesn’t continually change shape, I can put the notes on and define a centre line for the damper bar.

There are several different approaches used to control the movement of a damper bar; this system that I am making is my favourite.  It has the fewest number of parts to make, which means that it is quicker and cheaper to fabricate.  This also means that the tolerances (manufacturing discrepancies) don’t add up and become too great.  But above all that, it is the system that seems to go wrong the least number of times.

What I should say, is that I have no intention of replicating the system made by Premier and used on their 701 and 751 vibes.  The Premier design is actually quite neat, but it doesn’t really work very well, has an Achilles heel, and all the spares are now obsolete. 

wpid-img_20150428_163436.jpg

Back to the vibraphone.  Now that I know where the damper bar needs to be, I can make the levers around which it will rotate.  All of the manufacturers who use this system, fix the levers to the damper bar with screws.  I have used very thin wall steel instead of aluminium, so I have chosen to weld them on in position and have fewer parts to go wrong and end up with a more resilient design.  This is one major reason for choosing steel over aluminium, the other is that it is stronger.  Yes it is very slightly heavier than the aluminium the manufacturers use, but when that is substituted for aluminium stock that doesn’t bend in use, the thicker walled aluminium actually weighs more than the steel.  This is a common misconception about aluminium.



The connection rods between the damper bar and the pedal are always a bit tricky, both in design, where there is always a compromise, and in application.  The design problems are mainly concerned with ease of use when the vibraphone is being transported.  The issues in application are that they want to fall down towards the pedal exactly where the motor sits.  Therefore the positioning is also a compromise.  The actual method I use are simply tubes that have a telescopic rod that connects to the pedal.  This will be seen in 1260 (pt 3) when all the bits are back from the powder coaters and chrome platers.

Premier 701 Vibraphone (part 1) (Job No: 1260)

This whole job is a bit embarrassing, not for me, but for all the other people who have been associated with this instrument before it ended up in my workshop.  Most of all it is embarrassing for the man who bought as a birthday present to his son, discovered a problem with lack of damping, and ten months later the son is nearly another year older!

wpid-img_20150423_154938.jpg

I do have the notes and resonators, but as can be seen the damper bar is missing – taken to be repaired.  So the job is to sort out the lack of damping.

The damper bar on these Premier vibes is rubbish and now all the parts are obsolete.  Why anyone would go to the trouble of remaking parts to get a badly designed assembly to work is a mystery to me.  The main problem with the design is the leaf springs which work harden over time and snap like the top of a tin can when you wiggle it to get it off.  I could make new springs in an hour, but why make something that is destined to break?  Furthermore, because I don’t have the original damper bar I don’t know what condition the ball joints are in, or if the bar is straight which are the other major issues.

Immediately when the instrument was delivered I noticed a problem.

wpid-img_20150427_160010.jpg

The bottom bar which carries the pedal, and around which the pedal rotates, has been welded to the frame.  How could I resolve any damping problems if I were to ignore the point of operation?  First big question therefore is why the damper bar was removed for repair when the whole instrument should have been taken.

I know why the damper bar was welded into place.  As can be seen from the photo, several attempts have been made to sort the problem.  It’s unbelievably bad and so obvious only someone stupid would have failed to realise that the pedal acts against springs which therefore will try and rotate the tube.  So the two screws in the ends didn’t work because they have created a nice axle.

wpid-photogrid_1430294141180.jpg

The first thing to do is to make a new bar, because the only way to that one off is with an angle grinder.  Because the damper bar and springs slide onto the tube and are riveted in place the ends need to be both the same diameter of the tube and removable.

wpid-img_20150428_110324.jpg

I put flats on the under side of these caps which sit on a little square bar welded to the leg frames to stop the rotation.

wpid-img_20150423_172802.jpg

Whilst I was welding, I put mounting plates on for the casters – in the picture above it can be seen what the previous person did.

wpid-img_20150428_133620.jpg

The damping system will not work if the legs aren’t attached to the top frame or the frame to the note rails.

wpid-photogrid_1430297641776.jpg

The whole thing needed to be removed straightened and refitted, so that the top and bottom are now both solid, all I then had to do was join the two halves, except the holes don’t even line up.

wpid-photogrid_1430297818980.jpg

I think that the owner said that he bought the instrument from a school – I certainly hope that this is not the work of the metal work teacher, but I suspect it is.  As a digression, I applied to do teacher training in the early 2000’s, become a craft and design teacher; I was told that I was under qualified.  You don’t need a bloody degree to make something square!

wpid-screenshot_2015-04-29-10-03-532.jpg.jpg

That was hot, hard work!  Fire and brawn to pull the thing straight.  The frame that has been built (which actually needs to be binned) is massively heavy 6mm steel!  I would make a shelter out of this stuff and still guarantee it for life.

Finally I can assemble the instrument and begin to look at the actual damper bar which will be in 1260 (pt 2).

wpid-img_20150428_153742.jpg