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Double Bass Wood vs Metal Bridge Adjusters

bassically_eli

bassically_eli

Supporting Member
Feb 7, 2010
1,717
1,623
Virginia
#1
What are the pros and cons of wood (ebony, rosewood, or others) bridge adjuster wheels vs. metal ones (typically aluminum afaik)? The only thing I remember hearing is that the metal ones can be sticky sometimes and more difficult to turn. I've never had that problem with the aluminum adjusters on my ply bass (they're black, so perhaps they have a coating that helps).

Also, do wooden wheels always have a larger diameter on the threaded portion? I was just about to order a Lifeline pickup for a project bass that I purchased recently (no adjusters currently, probably needs a new bridge), but then I realized that I might need the XL version if I decide to go with wooden adjusters.

P.S. - I did a search and didn't find much, but I can't believe that this hasn't come up before. So sorry if this is a redundant thread.
 
#2
Adjusters are only "sticky" when they are not installed correctly, either crooked (pressure from the strings causes a pinching effect when the force is not spread evenly) or poorly machined threads. You can rub wax or preferably sliding paste on the threads to loosen them. I've seen the hole for the non threaded side drilled too small, even a few with masking tape shoved in there to I guess make for a better fit. The non threaded hole does not need to be tight at all, just straight and with as little friction as possible.

There are threads about the sound difference, the consensus was that aluminum had the least change in sound, though some still disagreed. I don't feel I've seen enough to say one way or the other. After installing adjusters I usually make so many other changes (sound post, tailgut spacing, bridge feet fitting) that pinpointing the adjusters effect is impossible. I don't get to work on a lot of very high end basses either.
 
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#3
Any thoughts regarding the Lifeline pickup size?
Brad_Pearson said:
Adjusters are only "sticky" when they are not installed correctly, either crooked (pressure from the strings causes a pinching effect when the force is not spread evenly) or poorly machined threads. You can rub wax or preferably sliding paste on the threads to loosen them. I've seen the hole for the non threaded side drilled too small, even a few with masking tape shoved in there to I guess make for a better fit. The non threaded hole does not need to be tight at all, just straight and with as little friction as possible.

There are threads about the sound difference, the consensus was that aluminum had the least change in sound, though some still disagreed. I don't feel I've seen enough to say one way or the other. After installing adjusters I usually make so many other changes (sound post, tailgut spacing, bridge feet fitting) that pinpointing the adjusters effect is impossible. I don't get to work on a lot of very high end basses either.
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#4
I think 1/4 20 aluminum adjusters are the most flexible for transmitting the vibrations. Yes the wooden or new harmony are a larger diameter. I actually have new harmony ones on my bass, swapped out the wooden adjusters. Think they are better then the wooden. If your adjusters don't turn you probably need the threads re-tapped. Lifeline pickup size only matters if you have wooden adjusters or any other large diameter adjuster. Get the xl size. To compensate for the thickness of the pickup do one less turn on that side of the bridge.
 
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#7
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#9
For the most part the load placed on bridge adjusters is static, but I would hesitate to use adjusters that were plastic, nylon etc. an exception for me would be the TUSQ/Graphtech stuff. I have made several nuts with them and they would be strong, light and low friction at the flat contact points, but with a metal threaded stud.

As for other materials, I have had bridges with wood and aluminum adjusters and I heard less of a high frequency damping effect with aluminum. Was it the lower mass and/or the difference in the velocity of sound through the materials? ‍♂️ Either way, it wasn’t a dramatic change, and less noticeable playing pizz.
 
#10
I have to admit that a part of me prefers the idea of wood adjusters for a nicer instrument (can't say I really care on my ply) and does not like the idea of the metal-on-metal pairing of the Lifeline with aluminum adjusters. BUT, my engineer brain says it probably doesn't matter, and that part is leaning towards a standard size just in case I decide to switch to the Yamahiko or Full Circle pickup someday.

Edit: the metal on metal thing has never actually been an issue. The Lifeline works great on my ply. That part of my brain is silly.
 
#12
On my bass, aluminum delivers a tad more highs compared to wood, but the difference of both compared to fixed bridge is rather minimal. I used to use a Lifeline with aluminum adjusters and the bridge legs were compensated so that the pickup side was 1,5mm shorter, if I recall. The bridge didn`t need the 1,5 turn compensation that way. For ebony adjusters you`ll need the XL size Lifeline.
 
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#13
I’m pretty sure that that adjuster didn’t break under normal conditions.

And while wooden adjusters have a certain aesthetic appeal, it seems that they would present more potential for problems. Since wood can swell or shrink (or even warp) under various conditions, they might not be the best option. Where else do you find wooden screws used for fine adjustments?

Regarding the affect on tone, everything on our basses can affect the tone. I think adjuster material would be fairly insignificant.
 
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#16
Stewie said:
Thanks James, now I'll have to call my friends at Gollihur. Anyone know if a Thompson ply has 1/4 20 threads? Or will I be cursing James as I remove my bridge to check?
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The String Emporium usually uses delrin adjusters that are bigger than 1/4 20. Sorry, I forget the actual size. As to James' picture, yeah that sucks. I have to say though - I've never heard of anyone else having that same problem so I'm guessing that particular adjuster was somehow damaged before or during installation.
 
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#17
bassmanbrent said:
As to James' picture, yeah that sucks. I have to say though - I've never heard of anyone else having that same problem so I'm guessing that particular adjuster was somehow damaged before or during installation.
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Hi BB,

I know of at least one other case where a Delrin adjuster broke. It's a shame because they have a nice "lubricated" feel to them, like lignum vitae. Bill Lakefield, luthier, started making Delrin adjusters with an aluminum insert down the length of the shaft. Not sure if he's still doing that...

Although the OP is back to 1/4" aluminum and a Lifeline, you need to be careful when assuming a pickup will fit with wood adjusters. Some wood adjusters are so large that a Lifeline (even an XL) is out of the question.
 
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#20
Well, ya know, plastic bolts are not used in stressed applications. It's darn easy to put a significant bending load on a DB bridge adjuster.

I'm not familiar with the construction of wood adjusters, but wood male threads into wood female threads is a pretty bad idea.

I'm not particularly enamored of metal male machine screw threads into wood female threads, either.

My bass' adjusters have a separate wheel. So when adjusting it's an aluminum disk with female threads, moving on a metal male thread; the rod with male threads being set into the bridge. I'm not sure of the material of the center part. It should be steel, but it's probably aluminum (not a good choice for a loaded thread, due to galling). I"m not sure whether I think metal machine screw threads into wood, or aluminum on aluminum machine screw threads, is a worse idea.
 
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