Yet even more changer questions!

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rogerogrant
Posts: 9
Joined: Sun Nov 19, 2017 11:15 am
Location: Austin, TX...y'all!

Yet even more changer questions!

Post by rogerogrant »

Hey y'all,

It seems I'm not alone in pondering the changer design and execution the most as I'm mulling over my planned build. I hijacked a thread with some initial questions, but reckoned I should be polite and start my own. :D

First, what is the general feeling about ball bearings to mount the control fingers on the axle? I don't think I've seen anyone using them, but I may have missed it - it looks like most folks mount directly on the axle. I'm of the superstitious mindset that lots of moving parts in guitar bridges and nuts = tone suck, but I think that superstition needs to be done away with in regard to the PSG. There are just a lot of moving parts period in the traditional designs. I know at least one person is pondering a keyhead changer mechanism which could theoretically mean a solid bridge and a solid nut (maybe...string breakage would be the deciding factor) but I'm not going to get too experimental with my first go at it.

Second, also related to the axle: for those that use a "comb" housing rather than just pillow blocks at each end, is any sort of bearing required between finger and "comb tooth"? I'm planning on making my control fingers 5mm wide (I'm born and raised 'merican and can only conceptualize things in Imperial units, but when building anything I go metric because it's just a whole heck of a lot easier for my arithmetic-challenged mind! :lol: ). For 10mm string spacing I'll then have 5mm between fingers. The sintered bronze (i.e. oilite) bearings that I've found are 1/16 inch thick, or about 1.5mm. That leaves me with a scant 2mm of aluminum for the comb teeth by my calculations (but see previous sentence about arithmetic challenges). Here's a sketch, in which pink highlighter is control finger and blue is aluminum comb tooth:

Image

Most of the pictures I've seen of the changers made by folks on this forum as well as on other guitars don't appear to have such bearings. This Pro 1 for example doesn't look like it does, although there may be something hidden:

Image

My other questions involve some "under the hood" specs.
I didn't actually pre-determine an angle for the bottom of the control finger when I was sketching it, I just did it by eye so it looked good. Taking a protractor to it now, it appears I hit upon 35 degrees. Is that too shallow? Theoretically that means less work for the return springs versus something steeper like 45 degrees, but I'm concerned about whether or not the whole surface is long enough for a full tone lower:

Image

The length at the bottom of the lower is 40mm. Reckon that's enough for return springs?

Thanks!!!!

-Patrick
maxi19
Posts: 365
Joined: Mon Oct 22, 2012 12:55 pm
Location: Milton Keynes, England

Re: Yet even more changer questions!

Post by maxi19 »

Hi Patrick,
I make my upper fingers from 20mm x 5mm brass, no bearings, I make and use 0.25 ptfe washers from sheet to fit between the finger units and the comb and this takes up any lateral movement or discrepancies.

Ron Mc
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