4.3 Octave Concert Grade Marimba

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Project by Wolfdrool posted 07-29-2016 09:57 PM 1667 views 5 times favorited 12 comments Add to Favorites Watch

I just finished building this marimba for my younger son, who plays in his school band and competes at competitions. Very challenging project, but very fun. Back in April, this was just a pile of wood and a stack of aluminum tubes.

The keys are padauk. The base is a mixture of hardwoods. Metal unistrut rails hold the upper rails that support the keys. Rubber is used to isolate these so the metal doesn’t resonate during play. Hockey pucks are the knobs at the ends that can be loosened and tightened to change the height of the strut assembly up to 8 inches.

The resonator tubes are aluminum. These were priced great from but were rough as supplied. Surprisingly, they easily polished up to look like shiny chrome using 150-220-400-600 grit sandpaper followed by 00 and 0000 steel wool followed by Mother’s aluminum polish.

The mallets shown were made to use during the build to tune the keys and resonator tubes so that good mallets would not get ruined. These mallets were fast to make from superglue, a couple pieces of dowel, rubber chair leg caps, baby socks to wrap the ends, and electrical tape to hold the socks on.

12 comments so far

View gargey's profile


1013 posts in 1135 days

#1 posted 07-29-2016 10:29 PM


View ClaudeF's profile


893 posts in 2067 days

#2 posted 07-29-2016 11:41 PM

Wow! Quite the project. Was it difficult to change the length of the tubes to tune the instrument?



View Wolfdrool's profile


57 posts in 3757 days

#3 posted 07-29-2016 11:57 PM

Claude: Tuning the pipes was pretty easy for all but the shortest pipes. Using a miter saw with a 90 tooth blade, I could shave off tiny amounts or bigger amounts from the pipes. The aluminum cuts easy and pretty smooth, but does throw off little metal pieces, so I had to wear one of those full face shield protectors. I had never cut aluminum with the saw before, so making the first cut took some gritted teeth. A chart of tube lengths gets you really close at the start. Tuning the pipes went really fast, surprisingly. The shorter pipes are harder to tune because they are too small to hold and use the miter saw safely. I made a jig to hold and cut the smaller pipes, and then it was fine.

View JoeinGa's profile


7741 posts in 2366 days

#4 posted 07-30-2016 12:28 AM

Dang! That thing is abso-freakin-lutely GEORGOUS !!! And I loves me some marimba music !

I see a photo of it being played, how ‘bout a video !

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View lightweightladylefty's profile


3335 posts in 4072 days

#5 posted 07-30-2016 03:19 AM

What an incredible accomplishment! You can enjoy concerts at home at any time of the day or night. What a treat!

Did you have a plan from which to work? Design it all yourself? Or did you just measure off another marimba?


-- Jesus is the ONLY reason for ANY season.

View Wolfdrool's profile


57 posts in 3757 days

#6 posted 07-30-2016 11:04 AM

L/W: I used excellent plans from to make the keys, resonator tubes, and to get the right dimensions, angles, etc. for the base. I designed the base structure under the keys myself as I went along, constrained by the proper dimensions for laying out the keys and resonators per the plans. Having built this one, I could likely build another in 1/3 the time with some improvements, but we don’t need two! I recommend the plans highly. The plan author is readily available for advice and feedback, which was very helpful. I’ve got some metal parts in here, and these need to be isolated by rubber strips or bumpers from the other parts to avoid resonating during play. I’ve built a lot of hand and motorized shop tools, but building this has to be the coolest project to date. Neither my son or I expected this to turn out so good, but the plans are that good. is also a good site as it has a lot of photos of custom made marimbas to give ideas for making the base.

View Calmudgeon's profile


260 posts in 1787 days

#7 posted 07-30-2016 01:00 PM

That’s a beautiful thing. I’m always intrigued and impressed by projects that have another dimension to them beyond the woodworking – in this case the musical dimension, tuning, ...

But with this you also have the added dimension of building something with and for your son.

-- "As are the things we make, so are we ourselves." - Lin Yutang

View gsimon's profile


1312 posts in 2473 days

#8 posted 07-30-2016 01:29 PM

awesome project – first i’ve seen here

-- Greg Simon

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1313 posts in 1993 days

#9 posted 07-30-2016 08:07 PM

Very nice.

-- Jeff NJ

View johnstoneb's profile


3100 posts in 2532 days

#10 posted 07-31-2016 03:37 PM

Awesome. I have the plans for a 3 octave marimba from makeamarimba. That I will be making for my grandson. I am really happy to see somebody else completing one. The padauk looks good as the keys that was my choice for the keys also. I have the lumber in my shop now just have to finish one project then will start. Did you tune the keys for the first overtone also and if so was it very difficult to do?
The base looks like it is adjustable for height.

-- Bruce, Boise, ID

View Wolfdrool's profile


57 posts in 3757 days

#11 posted 08-01-2016 07:54 PM


Is tuning keys hard? It was until I devised and learned the miter saw/drill press technique described below. Then it’s doable and even fun. This allowed me to do 8 to 10 keys an hour, which is way faster than any technique on the web that I found. I’ll describe it below.

I tuned to the fundamental and first overtone for about half my keys (A2 to B4) but not after that. As a coincidence, I found that this also got the second overtone right as well. The tone on my keys is excellent except perhaps C7 way at the top. I need to tune that again as it plays as C#7. B6 and C7, the tiniest keys, were the two hardest keys to tune because it was hard for the tuner to pick up their fundamental. Once they were strung on the instrument, it became clear that C7 was too sharp.

I practiced first on several hardwood scraps until I could get to the fundamental easily on the lowest keys. Then I practiced getting both the fundamental and the first overtone on practice low keys. It’s important to practice. I think you can use any hardwood for practice. Poplar or some low density hardwood might not work.

It worked best for me by cutting the initial arch to about half the targeted depth (your initial practice keys at your lowest keys will tell you what this depth is). Both tones will be way too high at this first stage. That’s good. Then work down the arch in the overtone area if the overtone is too high. Take a little of the fundamental zone if the fundamental is too high. This takes down both tones, but the overtone more. When the two tones are properly related, then you generally can take even swipes across the whole arch evenly to lower to the fundamental, but sometimes you have to address the overtone area or the fundamental area a little more to keep them good.

I struggled with taking too much time to make keys until I used the following miter saw/drill press technique. With this approach, I could do 8 to 10 keys an hour. I used a miter saw and jig to very roughly cut the initial arch shape to about half the desired depth. I highlighted areas of my jig in red where no hands are allowed, as this was a great, effective reminder, to keep my hands out of the cutting zone. The jig securely holds the key under the sliding saw blade so you can hold the jig way out of the cutting zone as you make a cutting pass. Your practice keys will tell you what this depth is. Cut the lower keys first in groups of 4 similarly sized keys. As you move to each new key group, make this initial arch depth a little less deep when the arch depth in your current set of 4 keys leaves you closer than 5 notes from the desired fundamental.

My 12 inch miter saw slides, and I added a pair of stops on the rails to control its sliding range of motion. I made a jig that holds each key, bottom up facing the blade. I take a pass, cutting 1/8 wide on one edge of the key. I now have a narrow arch about 1/8 inch wide. I move the jig over and make the next pass, etc., until the whole arch is made. Even though you cut this in several passes, it’s fast. The arch will be lightly grooved on the bottom when you are done, but its shape looks good. Move over to the drill press fitted with a 60 or 80 grit sanding drum. On a practice key, calibrate how much a very light pass, a moderate pass, and a heavy pass will lower the tone. The amount these passes impact tone is very repeatable from key to key. Your heavy pass should not be ridiculous because drill presses are not designed to take a lot of side thrust.

At the drill press is the place to get the overtone and fundamental into proper relation. Then, rough tuning to about 30 to 40 cents of the final fundamental worked well. This leaves plenty of room to final tune after drilling and final sanding.

I was worried that final tuning would be as time consuming as rough tuning, but it’s very easy and went fast. I put a 220 sanding drum in my drill press for final sanding. I very light touch over the whole arch lowered the tone 1 cent. A moderate (not heavy) touch took it down 5 cents. I did not use a heavy pass at this stage. Pretty repeatable on all the keys. I tested each key after each swipe, but it was very fast to get right on the final tone. I read that being within 5 cents is a finely tuned instrument, but with this technique, assuming the phone is accurate as a digital tuner, you get within a cent or two easily. Oil will add 1 to 2 cents.

Note I used iStrobosoft on my phone, which worked great as a digital tuner.

I’d sand the keys to 220 before doing any arch work, because this is easier to do while the keys are all square. Then all you have to do later is drilling, final sanding, the final tune and oiling. I used masking tape to label the keys but then switched to using a sharpie on the bottom flat area as the masking tape would fall off.

View johnstoneb's profile


3100 posts in 2532 days

#12 posted 08-11-2016 08:43 PM

Thank You. I like your cutting part of the key away before going to the sander. I don’t have a sliding miter but the table saw will do the same. I have an oscillating spindle sander was going to use that for everything. The saw will help with that.
I built a glockenspiel just to get the tuning practice. The heat from sanding on the aluminum really changes the tune. I would get close . Let it set for a day or so then tune again. I did that twice and got within a cent or 2 which really made me happy. My experience was the C7 tuned right in. The C3 still isn’t right If you hit in the exact right place it will be right on but any where else it is sharp. I ordered the tuner that makeamarimba recommended using. Trouble with it was it didn’t show the octave. I found a stroboscopic app on line for my kindle fire for $2.25 and it worked great. The strob display really made it easy when getting close.
Glad to know how the oil changed things I was wondering if it would. This will give me something to do this winter.
Thank you.

-- Bruce, Boise, ID

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