MIDI Pedal Board, the casing

How about a music gadget build project? This blog hasn’t seen one in.. err.. almost two years, so here’s one for change: Converting a 70s Hammond (or is this 80s?) organ to a MIDI foot keyboard / pedal!

The Hammond 123J3, photo by the internet.

The Hammond 123J3, photo by the internet. Mine was missing the note holder board altogether.

Background

A friend donated me this Hammond 123J3 organ that had some broken oscillator divider chips, bad solder joints on the PSU and a missing note holder stand. Solder joints I can handle and the note holder; not an issue, don’t care, whatever. However the dividers.. As the 123J3 is of japanese make and transistor based, it’s not one of those sought-after Hammonds that fetch for good buck$$. Thus it likely would’ve not been worth the effort to try sourcing the rare divider chips & fix the organ back to its original condition to be sold for next to nothing.

But it would be a shame to toss the whole instrument to landfill too.. One of those things to break a musicians heart! But perhaps at least some bits could be repurposed?

Initially my plan was to turn the whole organ into this epic music workstation. There’s ample space inside the organ, so you could easily chuck in a desktop computer, set up a your screens on top, midify all the controls and end up with this certifiably unique all-in-one DAW+keyboard+controls of a monster.  A true retro-spirited beast to rule all the sleek modern keyboard workstations.. And it would’ve even had a nice spot for the mouse to the right of the lower keyboard! :)

After taking some time to come to my senses, I gave up on the idea due to space requirements (in Finland we have this thing called ‘hellasärö’). Instead I settled for a less grandiose and a way more compact build. The plan: mod / hack the 123J3 down to the bit that’s off most interest, the foot pedal keyboard & volume (swell) pedal!

I already have the pedal in good use, so let’s get down to it. This first part is about building the case. Casing. Enclosure. A shell. Or what the hell you might call this?!

Chop shop

The 123J3 has plenty of particle board, angle brackets, screws and other mech bits to source parts from. This made building the case pretty straightforward, as almost everything was at hand from the get-go. I didn’t bother designing the measures thoroughly either, just winged it as I went along. As usual this caused a few minor issues along the way, but nothing that would end up with the project getting binned. My plan was something in the lines of:

  1. Stop (the organ gets it). Hammertime.
  2. Trim down the neatly removed side panels.
  3. Remove the bottom board (with pedals) and make it as compact as possible.
  4. Somehow install trimmed side panels.
  5. Make & install some sort of rear panel to hold connectors.
  6. Trim down the top cover to whatever that fits the rest of the build.
  7. If some of the original hinges are good for making the top cover “flip to open”, try to include them despite having such a feature is totally pointless for the project.
  8. Admire the wonderful & compact pedals for a while, then move on to electronics

That said, the photos..:

The side panels ready to be chopped

The side panels ready to be chopped.

The top and bottom boards of Hammond 123J3

The top and bottom boards.

Compacting the bottom board: The volume (swell) pedal can move about 5cm to the left

Compacting the bottom board: The volume (swell) pedal can move about 5cm to the left. Also the right side can lose a few centimeters.

I actually trimmed the board a bit too short on the left edge. This turned a minor design flaw just shortly after as I got as far as to install the side panels. Problem is, with the side panels in place you simply can’t remove the volume pedal from the bottom board without first removing the side panel (too close) next to it. Oh well.. Figured there’s very little need to remove the volume pedal once I’m done with the build, so no biggie.

The trimmed side panels needed a wider groove to slot in the bottom board.

The trimmed side panels needed a wider groove to slot in the bottom board.

Add some wooden bits to allow affixing the side panels to bottom board

Add some wooden bits to mount side panels to bottom board.

I also added similar wooden bits to the top of the bottom board, as having them only against the bottom made the entire build somewhat flimsy. On the original design, the bottom board had both edges thinned down to fit the narrow slot on the side panels, and this step-shape made it more sturdy than my “I’ll just cut it straight” approach.

Side panels ahoy!: Meet the bottom board

Side panels ahoy!: Meet the bottom board.

On the bottom side, things look like this.

On the bottom side, things look like this.

Side view: The volume pedal is slightly above the side panels, so the top board will need an opening to match.

Side view: The volume pedal is slightly above the side panels. Top panel will need a hole to match.

Ooh I'm so excited: A not-so-promising quick mockup of what the pedals might look like!

Ooh I’m so excited: A not-so-promising quick mockup of what the pedals might look like! Also a good demo on how much did the bottom board actually compact..

The pictures above might give it away but I’ll say it anyway: The top board sure needed a good bit of trimming to fit. Besides matching the width of the bottom part, small notches had to be cut to the front (for side panels), a slot for the volume pedal milled accompanied by a few ~3mm deep grooves on the inside. These grooves were a mandatory extra bit of work because I cut the side panels without taking too exact measures. They turned out too short to line up neatly with the rear panel and pedal spring mech, and without the grooves the top panel would’ve just floated on top of the mech parts, leaving nasty looking gaps to the sides. No no no, not having any of that.

The rear panel I cut from Hammond logo metal bar, the black part that runs between the upper & lower keyboards (check first pic perhaps?). I removed the Hammond logo from the bar for later use, as surely a build like this can use some fake branding later on.. :).

Once both the top & rear panels were all good, I took a couple of L-brackets from the organ remainders and used those to secure the two together. Using hinges like I planned initially would’ve required too much extra drilling and ugly visible bolts, so I decided to scrap that idea. For the L-brackets there were two readily available holes so I didn’t bother installing more. Besides, making a sturdy solution by having some towards the front edge of top cover would’ve once again meant ugly visible bolts (oh noes!). As-is, since there are only the two brackets affixing the top cover to the rest of the case, the pedal board absolutely can’t take any lifting from the cover. Do that and the particle board will probably just break from all the weight.

Yup, with all the thick particle board & metal bits, this pedal actually isn’t any feather-weight thing :)

One of the L-brackets fastened to rear panel.

One of the L-brackets fastened to rear panel.

Thanks to the grooves I had to mill on the inside of top panel, the L-brackets didn’t align flush with the inside surface (a nice 3mm gap in-between). Nothing better at hand, so to work around the issue I folded small bits of cardboard in-between:

Do it like the pros: Use a pizza box to fix the short-comings of your mech design. Also visible, the milled inside grooves!

Do it like the pros: Use a pizza box to fix the short-comings of your mech design. Also visible, the #!@%#11! milled grooves.

..And with the brackets in place, I had finally reached step 8 of my initial plans..:

The case, all good to receive electronics!

The case, all good to receive electronics!

Yeah there it is. Electronics coming up on the next post, stay tuned!

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