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A P3 Marimba with small structural Mods
(built by David Grady)
This is David's first marimba, and he has done a tremendous job. Not only did he build a great marimba to the instructions, but he managed to improve structuaral strength a little with some simple but elegent modifications.
I finally finished the marimba today. Attached some pics. Looks pretty good I think. Sounds good also. The canary wood frame really complements the padauk color. You will notice that I aligned the lower horizontal strut with the center vertical on the small end instead of centering it. It just seemed like a good thing to do. I ran the diagonal struts on both resonator banks from the inner verticals on the big end frames all the way to the corresponding horizontal aluminum strut. As you can see in the photo detail, I riveted the diagonal and horizontal struts together just before the horizontal entered the small end frame. I riveted every resonator to the diagonals. Some rivets had to go through the end caps which required a slightly longer rivet. I kept the end of the diagonal at the large end frame as low as possible (like you indicated), and made the angle such that the diagonal brace was never below the bottom of any resonator brace. I smiled when I read your statement about the diagonal bracing where it stated something like 'for you engineers out there' ...I agreed with your instructions until it was actually time to make and attach them. Making those diagonals continuous and attaching them at the upper end completes the 'structural triangle' which will really strengthen the frame.
Let me know what you think......about the pics and the changes......
Well David - what do I think?? I like it! Whilst the P3 has certainly proven strong enough with the original design, these modifications certainly can't hurt it at all. There's no doubt this will make it stronger still. I avoided this in the original design because it can be quite difficult to find a line where the resonator caps do not get in the way. It seems that you have not only found a line for the diagonal that beats this, you are actually using it to your advantage when lining up over the aluminium horizontal. Nice work indeed!