$15 Foot pedal left mouse button project

I used to do 3D animation and devloped tendinitis in my right index finger from using the mouse so much. Normally, it’s not too bad, but it can be painful sometimes. I tried different sized mouses, trackballs, etc. but clicking the left mouse button always hurts. Trackpads are a solution, but I just like the feel and accuracy of a mouse. Anyways, I found the Fentek foot pedals, but being the cheapskate that I am, I was unwilling to part with $95 for a foot-operated mouse button.

After thinking about it for a while, I came up with the idea that I could hack the components of an old mouse with a foot pedal used for electronic keyboards. The switch used in these type of pedals are normally open and momentarily closed when depressed…essentially a foot-operated mouse button. I was able to put a working unit together for about $20 and here’s how I did it:

Parts List:

  1. M-Audio SP-1 Sustain Pedal I found it for $15 online, plus shipping
  2. A USB mini-mouse. One of those tiny ones that usually come with a retractable cable. I got mine as a freebie giveaway from somewhere. Here’s a Amazon link, but I’ve seen them on eBay for $5.99 with free shipping.
  3. Pliers
  4. Soldiering iron
  5. Electrical tape
  6. 2-conductor wire. Only a couple inches needed and you could get away with using the existing wires in the foot pedal.
  7. USB extension cable, if your PC doesn’t sit on the ground

First, disassemble the mouse and take the circuit board out of the shell. Mine had a pair of screws on the bottom. (One screw was beneath a sticker.) The scrollwheel should just come off, but be careful not to disturb the cable wiring. You can disgard everything except for the circuit board and the attached USB cable.

You can either de-soldier the three little switches and the scrollwheel mechanism or just carefully snap them off by rocking them back and forth with pliers. I took the latter route.

Open up the foot pedal by unscrewing the two screws on the left and right sides. The spring will be loose so be careful not to lose it. Save these screws and spring in a safe place. Also remove the screw in the bottom left corner of the circuit board (see picture). You can disgard this one screw. The mouse circuit board will lay over this area and you need the space and also don’t want that metal screw shorting anything out.

Now, you can either carefully bend the back corner in to make an exit for the USB cable or you could drill/dremel an opening. I was lazy and don’t have a dremel, so I just bent it in with pliers.  Note that if you bend it you need to be careful because the pedal cover is screwed into the side and you don’t want to get it out of alignment.

Next, soldier the wires to the two soldier points that are used by the right-mouse button. Soldier the other ends to the foot pedal circuit board. One conductor where the red wire is connected and the other conductor to where the black wire is connected. If you want, you can remove the foot pedal wires, but it’s not required. Cut off the big cable attached to the foot pedal circuit board and disgard.

[The soldier points and the screw removed]

[A bird’s eye view of everything]

Now, orient the mouse circuit board along the left space of the footpedal with the IC facing up. It won’t totally fit and some of it will lay over the pedal board circuit board. You’ll need to move the wires around the foot pedal board so that the mouse board can lay as flat as possible.

[Route the wires in the cavity around the foot pedal board]

[The mouse board should not protrude (much) above the top of the case.]

You can plug the USB cable into your computer and test the switch now. Just press down on the rigid wire on the foot pedal board. If it doesnt’ work, check your wiring. It’s very basic circuitry. When the rigid wire is depressed, it completes the circuit. When not depressed, the circuit is open.

Once it all works as expected, put some electrical tape over the top of the mouse board to ensure no shorts occur when the pedal is depressed. Put the spring back in it’s place. Screw the top of the pedal back on.

One downside of using the mini-mouse is that the retractable cables tend to be on the short side. Thus, I had to use a USB extension cable for the unit to reach the ground. You may not have this issue if your PC sits on the ground, but I’m using a laptop.

Well, all in all, it’s a pretty quick and easy project. The mouse was a freebie I got somewhere and so the entire project only set me back $20 including shipping on the $15 pedal. It is probably a little more “springy” than I’d like it to be, but maybe it will loosen up over time. Enjoy!

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