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60K views 54 replies 16 participants last post by  léomaurel 
#1 ·
My third bowed keyboard

After nearly 2 years of planning and other projects…I am FINALLY starting another bowed keyboard; a streichklavier. It is basically a bowed harpsichord, similar in concept to the wheelharp project I posted earlier. http://lumberjocks.com/projects/3563
I realize I never finished my blog on that (if anyone was following it) but I kind of went about it backwards by posting the finished project, then trying to blog it's construction. How this instrument turns out will be as much a surprise to me as it will you all!
While the wheelharp is a type of geigenwerk, which uses a rosined wheel as a bow, the striechklavier uses a rosined belt as a bow. It differs somewhat from most attempts (I think) due to bridge placement being opposite harpsichord or pianos, and a few other little differences I am going to try. These are a very experimental instrument, with very few working or existing models. Akio Obuchi, a harpsichord builder from Japan, is very dedicated to bowed keyboard research and construction. He has been very helpful with my experiments with these type instruments.
(Google Akio Obuchi if you want to see his work)

I will elaborate more on this instrument as time allows, but I am racing the clock to get it done. I want to have it working at least somewhat to display at a festival our town puts on every May.

This was my first attempt at real dovetails (I did a practice corner last summer) and I'm sure there are lots of people who could do nicer ones with a chainsaw…but I think they'll look ok when trimmed up, and the main thing is, I want the corners STRONG. I can't believe how strong dovetails are, even without glue.

More to come…

vacuum bagging curved side

vacuum bagging curved side

chiseling dovetails

dovetails

bowed keyboard, streichklavier

bowed keyboard, streichklavier
 
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#3 ·
Yeah, they made my head hurt…I cut the outside of the corners at the proper angle, then layed out the dovetails one side and cut a clear template from acetate. I then transfered the pattern to the back side and connected the lines. I did a lot of "eyeballing" though; imagining how one board would intersect the other. I will definately post video as I get it working.
 
#4 ·
I just used finger joints on my harpsichord. I figured the it was to prevent the joints from collapsing rather than exploding.

Looking great so far. I can't wait to see it completed.

Can you do a video of your other instrument. I would love to hear what it sounds like.
 
#5 ·
Gary, I arranged the dovetails so that as the strings pull the case together, it tightens the joint. Propably not needed, but I don't want the corners popping apart. I arrived at the shape by using a stringing chart for harps that gave optimum string length, then calculated my harmonic curve. Akio Obuchi (who I mentioned earlier) recommended best bow placement for strings, so I aligned everything with the bow placement as a centerline and skewed the harmonic curve and bridge (which is under keyboard end) to fit bow placement. The bridge distance is matched fairly close to violin, and bass, depending on which part of the scale you're in. I made a clip (not real video, sorry, just a picture) one is from when I first built it, and another recording from a couple of months ago. It is very hard to get everything working at once…it was working better the first recording, but the record levels weren't as high. This new instrument should have a brighter sound as it is steel strung instead of nylon, as the wheelharp.

http://s261.photobucket.com/albums/ii49/wheelharp/?action=view&current=wheelharpclipbyJonJones.flv
 
#7 ·
It's about to stand on its own...

Over the weekend, I got the case all glued together. Ideally I would have like to let the dovetails hold it all together, but hopefully I won't ever need to take it apart. I got the bottom cut and set in a rabbeted channel in the bottom, but still have to glue it.
test fitting bottom
I got one of the cabriole legs done, and the other 2 are glued up ready to cut. I couldn't wait and had to prop it up and get a look. If the whole picture doesn't show up of the leg, click on it, and I think it will open new window in photobucket where you can see all of it.
first cabriole leg
My strings and tuning pins arrived in the mail from Musicmaker's kits…I'm getting excited now!
 
#28 ·
soundboard done

The soundboard is done (but not glued on yet) bracing is in, and I think I'm very close to stringing it up. I may go ahead and apply finish to outside before I string it, so all the "nasty" work will be done before detail work. The soundboard is spanish Cedar…not sure if that is a good soundboard material, but saw it at the sawmill and just had to have it. The lid is done except for the flap that covers the end, and cutting it apart so part of it can fold back. It sprung a little, but I'll whip it into shape with the latch mechanism that holds it down.
bracing in
trim on
soundboard test fit
lid
 
#36 ·
Adding strings

Been a while since I posted progress, but I have been busy. Both on this, and installing an alarm system so I hopefully can keep my tools till the project is done (long story)

An overview as to what this is: A harpsichord shaped instrument that will use a treadle driven belt to bow the strings when a key is pushed. It will use a different bridges and stringing arrangment than harpsichord- this is more like a big hammer dulcimer in design.

I applied dye and laquer- still needs work, but it's getting there. I liked the natural look, but there was a lot of green to cover in the poplar.

strings on 5-3-09

got the flywheel amost done…still have to attach the treadle plate and pitman arm, connnecting rod, or whatever you call the thing that goes from the pedal to the crankshaft.

flywheel and treadle

strumming the strings…

http://i261.photobucket.com/player.swf?file=http://vid261.photobucket.com/albums/ii49/wheelharp/MOV03209.flv

plucking the strings

http://i261.photobucket.com/player.swf?file=http://vid261.photobucket.com/albums/ii49/wheelharp/MOV03214.flv

If the bow mechanism doesn't work well, I may convert it to a type of lautenwerk (sp?) which is a cross between a lute and a harpsichord.

I have 2 weeks to get done...don't know if it's going to happen or not.
 
#41 ·
back at it- ready for the keyboard

In case anyone was following this project, I haven't given up…I just had to get away from it for a while. I didn't get in done in time for the festival in May, but I did take it to show what I had done. I had spent so much time in the shop I was really testing my family's patience, not to mention all the odd jobs that had piled up. The first order of business was pressure washing and sealing a chapel on my mother's property that the family built as a memorial to my brother who died in 2001.
chapel
After that we sanded all the hardwood in our house and recoated with Varathane. What an ordeal, but I won't go there now.
hardwood
After a whole summers worth of this and that, a few weeks ago I figured I better tear into this thing again if I wanted to take it to the fall music festival Oct 17. Not really sure at this point if I have just wasted a lot of time on a fancy parlor decoration that looks like an instrument, but I figure I'll go ahead and finish it and see what happens. I made a new smaller pulley on the flywheel to increase the speed I can pedal it- thus building more inertia while srill keeping belt speed down. It's amazing what 1/2 reduction in pulley diameter can do. I also put a new belt on it (nylon ribbon). I rebuilt the guard rollers that keep the belt off the strings, my wife said the first one looked pretty rough. I didn't really care - it's hidden, but I made a new one anyway.
streichklavier peg guides
I then made a guide rail that holds little "fingers" that push the belt down on the desired string that you want bowed. At this point I'm making things up as I go. I have made sketches, but it's hard to tell what's really going to work until you can manipulate the working parts and see what they will do in reality. A lot of times I have found I spend way to much time figuring out a mechanism, as it turns out easiest way to do it works best. Now I'm to the point of making the keyboard which will directly set on top of the pins which push the belt down. I have a low quality video clip of me pushing the pins in without the keyboard…gives a little preview of how this works, and what it will sound like. The knocking noise is a loose crankshaft on my flywheel-and by the way, I'm NOT a keyboard player:) I have a week and a half before the festival. Maybe THIS time I'll get it done, but I'm not holding my breath…
http://static.photobucket.com/player.swf?file=http://vid261.photobucket.com/albums/ii49/wheelharp/MOV03257.flv
 
#42 ·
First time seeing your project. You are quite the inventor.

I have been at the "much time figuring out a mechanism, as it turns out easiest way to do it works best" point many times. Some of my things have ended up being a Rube Goldberg prize contender.

Looking forward to seeing and hearing the finished product. (Even if for the 2010 festival.)

Steve.
 
#45 ·
at the fall music festival in Ironton MO

I didn't get completely done, but took it to the festival anyway. Friday night I had it working pretty good about midnight, but as I was getting ready to put it away for the night- I heard a popping noise every time the belt made a full circle. I knew what that meant… time for a new belt. I cut the old one off and spliced a new one on. I use gorilla glue and clamp the splice between waxed paper. this time I used maple blocks and two clamps so I could really crank down on it. Sat morning it looked good, but I didn't really have time to get it broke in properly (rosin worked into fibers) I took it town and set it up- It was starting to work, but the 45 degree temps really started working on the rosin. It lost it's "grab" and began slipping on the drive pulley when you engaged a key.
streichklavier at fall festival 2009

I kept it at the festival for about 3 hours, then gave up and took it to the house. After I catch up on a few things- going to try and tweak it some more- I'm going to move the keyboard, and add a second keyboard and hardware to pluck the strings in addition to bowing them. I hate that this is taking so long, but this has really been time consuming, and I can only work on it for so long as it pushes the limits with family and work. Just aren't enough hours in the day. Hopefully before long I can post it as a FINISHED project with sound samples.
 
#49 ·
A short recording of bowed keyboard

For those of you that have not seen this yet, a short recap…A harpsichord type instrument that uses a rosined nylon belt driven by a foot treadle to bow the strings when a key is pushed. This is a little video I made while it was working halfway decent. The first little clip is shot with video mode on still camera- the rest is an audio recording with older shots of construction to fill the video void. I plan on adding another keyboard that will pluck strings similar to a harpsichord, but with softer plectrums to sound like a harp. The squeaky noises are little rollers that need oiled. The belt also slipped once if you hear something like a seal barking…

http://static.photobucket.com/player.swf?file=http://vid261.photobucket.com/albums/ii49/wheelharp/streich2_0002.flv
 
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