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Musical Instruments #6: Marimba Getting ready for final tune

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Blog entry by johnstoneb posted 12-26-2016 03:51 PM 386 reads 0 times favorited 1 comment Add to Favorites Watch
« Part 5: Marimba Resonators Time to build Part 6 of Musical Instruments series Part 7: The Resonators and completion »

The keys and resonators are made and have a rough tune. It’s now time to get everything ready and do the final tune.
We need to drill mount hole in the keys before we can tune, first we need to locate and install the suspension components. The glockenspiel taught me that location and spacing of the suspension is a critical step. Space the suspension to close and the keys rub against the suspension causing vibration noise and affecting the sound from the keys too far and there isn’t room for all the keys.
The plans call for using small eye screws and I was originally going to go that way. The line that supends the keys has to go thru the eyes and once installed to remove a key requires removing the line from all the keys andit also makes removing the resonator assembly more difficult when taking apart to move. I went back to the manufactures website to see how they suspended the keys. I found a video of the keys all strung together in a roll and they just laid the key roll on the support and unrolled them on these open U shaped things. I immediately googled marimba parts and found what I needed. I had to look a little but did find a site that had them at 10 for $9 I ordered a pack thinking I could make some. I got them they were going to require more labor and time than I wanted to put into them so talked daughter into getting enough to do the job. You can see them in the second picture.

Located marked and drilling The plans give the dimensions because I was using a different suspension I went just a little bit wider between keys. I laid everything out in pencil then laid keys in til they fit. Then went to scrap pieces drill mounted some suspension pieces and made sure everything worked right before drilling final holes.

Installing supports and making sure straight

double checking fit.

In this last picture you can see I have put some heat shrink on the uprights. This serves as an isolator in the event that a key slides over and makes contact with the upright this stops the vibration buzz. There is also room to cut small circles of felt and put over the line if necessary. The heat shrink is from harbor freight.
The suspension is ready now we need to drill the keys so the cord can go thru for suspension. I am using a 1/8” 3mm nylon cord. I need slightly larger than 1/8” hole. I drilled different size hole in scrap to get the size I needed. I think I ended with 5/32. The cord slides fairly easily but not to loose. You want as small a hole as possible. We know what size hole to drill. Where do we drill them. Pass the salt. That’s right salt. The holes need to be drilled at the nodes. Sound travels in a wave each note having its own wave length. The center of the key is the high spot in the wave and we want the holes located where the wave passes thru the bar.
I suspended the key on top of bamboo skewers on the frame and sprinkled salt on the key and using a marimba mallet played the key the salt vibrates to the node location now you know where to locate the holes.

salt on

Voila! Mark the edge

Drill straight

Drill the angled hole in the right direction.

Everything suspended, holes line up, actually get music from the keys but not the marimba sound. I hope those resonators work.

At this point that was my big worry. I did not know what things were supposed to sound like at this point. I tried holding a resonator under a key but couldn’t get the sound I should out of it.

I guess we will continue and hope the author of the plans know what he was doing and I did things right. We will do the final tune on the keys and resonators and install the resonators next.

-- Bruce, Boise, ID



1 comment so far

View crowie's profile

crowie

1712 posts in 1554 days


#1 posted 12-27-2016 06:30 AM

There is so much work in this masterpiece….

-- Lifes good, Enjoy each new day...... Cheers from "On Top DownUnder" Crowie

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