Beat It

Over the course of several weeks I had to refine and re-engineer the bass drum beater mechanism. I only have photos of the final configuration, because I was too busy getting the damn thing to work to remember the camera. You’ll have to settle for my crude diagrams.

Essentially, the original design wasn’t good enough. A simple lever action didn’t provide enough velocity and/or force for the beater to hit the drum face hard enough.

 

I had a close look at a proper bass drum pedal, and noticed that the link between the pedal and the beater is actually a chain that winds around a gear fixed to the beater pivot axis, and wraps about 3/4 of the way around. Furthermore, the gear can be made eccentric, so that when the pedal is actuated and the beater “unwinds” towards the drum, it accelerates faster as it travels.

 

 

After studying this design, I decided I could incorporate it into my pedal. There wasn’t a lot of room to work in, and the size and position of the beater anchor and the cable feed meant that I had to use an extra pulley. I couldn’t find a pulley at the hardware store that was small enough, so I ended up fabricating my own out of a wooden dowel with a crude (plastic file folder material!) sleeve bearing around a mounting screw axle.

 

 

I had to experiment with different return spring rates and amounts of weight on the beater head but eventually I got something that worked and felt reasonably close to a commercial bass drum pedal. Coupled with the new skin on the bass drum it could now make a THUMP that shook the windows! (Well, as long as the windows were directly behind the open back of the drum…)

Unfortunately, after several hours of use the cable broke. I replaced the cable only to have it break again, in the same spot – right where it rounds the pulley. Apparently the curve is simply too sharp for the bicycle cable and with repeated flexing over the pulley it will eventually fatigue enough to break through.

So I went back to the original venetian blind cord… but only for half the cable length. Mounting another anchor point on the base plate, I split the cable and put a simple connection between the cord and the cable. This has the added advantage of allowing me to adjust the cable length without fighting the springs.

 

I really hope I don’t have to revisit this again because it has been one of the most time-consuming parts of the entire build!