Bridge mod- from fixed to adjustable?

Ortonomics · #1 04-06-2010, 03:32 PM

Hello everyone, I just recently got my first upright and am in love. The sexiest thing I ever played with that didn't talk my ear off afterward.

Okay, somewhat inappropriate jokes aside, I am planning to modify the fixed bridge to adjustable so I can start playing with the action and different strings to find my most comfortable zone. I have plenty of woodworking skill and am technically inclined so it is something I can manage, but is there anyone who might have tried this before?

Namely I am curious about the adjusters themselves. I can make them out of brass or sterling silver, however I have read that hardwood adjusters (threaded post and all) deliver a better tone to the top of the instrument. I wondered if anyone has any suggestions on this point... It would be a lot easier to make them out of metal (for me) however if it's a significant tonal improvement I will try the hardwood approach.

Any thoughts are appreiated and thanks for the great forum with tons of excellent advice and tips!

-Michael

Andrew McGregor · #2 04-06-2010, 04:15 PM

You can just buy the adjuster parts. All bridges start out as non-adjustable blanks, and the adjusters are fitted later. It's a tricky job to fit them into the bridge, but if you're able to make adjusters from scratch I expect you can do it.

I haven't noticed any tonal change fitting adjusters to my bass (mine are aluminium), so I wouldn't worry about the material too much. Very heavy adjusters might change the tone, I suppose.

Cody Sisk · #3 04-06-2010, 05:25 PM

This thread is a good place to start.

bigolbassguy · #4 04-06-2010, 06:02 PM

I think the general consensus is that aluminum adjusters sound the best. Many people swear by wood, and there is an audio test that was published a few years ago that, on paper, appears to confirm this. However, it seemingly contradicts itself. At the bottom of the page is a link to some audio samples of the different adjusters tested. You might disagree, but I think the aluminum sounds better than maple. You wouldn't think so, but check this out if you need proof.

http://iwk.mdw.ac.at/Forschung/engli....htm#realaudio

Hope this aids you in your decision.

Ortonomics · #5 04-06-2010, 06:27 PM

Groovy, thanks folks. I could also make them from aluminum, now that you mention it. It's a lot easier to machine and it makes sense that it would transfer the vibration better due to it's rigidity and low mass.

Typically I am a DIY guy but I will do a websearch to see if Aluminum adjusters can be found cheap but at the moment I would need money just to say I'm flat broke, so given that the materials are either cheap or free I will probably make them.

Eric Hochberg · #6 04-06-2010, 08:00 PM

$10.95 from Lemurmusic.com.

Ortonomics · #7 04-06-2010, 09:01 PM

Dallas, thanks for that thread link, I thought I did I thorough search but apparently not. Anyway the info there led me to the Moser bridge. I checked it out and in concept it seems like a logical design improvement, although when talking about classical instuments, the word "improvement" is a loaded gun, and not appreciated by everyone.

Anyway... being that I enjoy making things, I will redesign my own version of moser's idea and apply it to my own needs. I will keep track of the project and post pics.

And btw I respect copyrights/patents (especially when it's a good idea!) so I am only doing this for myself. No patent violations if I don't sell it!

Thanks for the help y'all!

sjd007 · #8 04-13-2010, 05:32 PM

I did my bridge about a year ago. Glued it to a biece of hardboard then cut it with a mitre saw. That keeps the feet in the correct position for drilling wiht a drill press, and the rest of the bridge for drilling and tapping the thread.

I bought aluminium adjusters (as Andrew said) - really cheap but very well made and very light. I "modified" them by drilling about 6 holes around the wheel part to reduce mass, but mainly to make them look cool.

The bridge needed a little refining of the fit to the soundboard (the sandpaper trick) as even being very careful it still wasn't 100% aligned once put back together, but all in all looks fine and works well. No tonal change that I can tell. Bit of graphote on the threads a good idea too to keep them from sticking under tension.

Good luck - it is fun having a play, and at the worst you can always buy a new bridge...

Tim Skaggs · #9 04-13-2010, 08:04 PM

I can tell you that when you prep a bridge for adjustment wheels, the aluminum wheels are more forgiving. I've drilled and cut a few bridges with no problems when fitting aluminum wheels. I've completed a few with wooden wheels, but I've also split a couple bridges when prepping for wooden wheels. The issue is the diameter of the shaft on the wooden wheels is much larger than the aluminum (like 1/4" vs 23/64"). It requires that you get the hole up through the bridge feet very evenly centered in the bridge legs. If you get a little off center, you end up with a thin side and when you start cutting threads, it's not difficult to get a split. If it doesn't split when threading, it can split later on when under stress.

It's obviously not impossible to get it right, but more difficult. The aluminum shaft being so much smaller in diameter allows you to retain much more of the original "leg" by drilling a much smaller hole. You still want the hole as dead center as possible, but there is a little more room for a slight error.