I want to adjust the action of a banjo built with a dowel stick. To shim would you use a metal or wood shim?
Which metal would be the best for transferring the sound from the arm to the rim if used metal--brass?
If wood any particular species of wood?
Your thoughts on this topic.
I used shims to lower the action on several banjos with dowel stick. Generally it works perfectly, I used wood or plastic (credit card for example), never tried metal. In my opinion sound transfer comes mostly from the heel, more than the fretboard. I even played banjos with a gap between fretboard and rim which sounded great. But that is an endless debate, so the best way : try and you'll get the best information.
You will put undue stress on the dowel stick by doing this and could warp it. You are better off resetting the entire stick and reshaping the heel. If this is an antique banjo you are talking about, I advise leaving everything as-is.
I have used thin aluminium to shim Zither banjos. Mind you this instruments doesn't have a dowel stick but I have shimmed dowels stick instruments. The Ali came from an offset printer plate and is thin enough to cut to size and fold. I also have veneers of rosewood and maple. As John has said, It can put strain on the dowel and other parts. Whenever I work on old banjos, the necks have invariably pulled up over time due to tension, mostly being strung with steel strings when they shouldn't have been. The task is to get them playable. As I am not set up for major work like resetting dowels sticks, I have to use other means. Mostly is a combination of lowering the bridge and shimming the neck. Most of the time it works.
I'm with John Cohen on this one. Shimming is not good for the stick itself, nor is it good for the glue joint where it fits into the neck heel.
I agree with those who would not shim a dowel stick banjo on the grounds that it really stresses the dowel / heel joint and can stress the rim to boot. There's no good way to adjust the action on a dowel stick banjo other than changing the bridge height.
I don't completely agree with previous posts, because it depends on how much you need to adjust action. Generally puting a shim of a credit card thickness is not stressful enough to damage anything, but it is a maximum thickness and it's generally enough to make the banjo playable. Of course if you need more adjustment it's obviously not the right way.
Another thing you might try is to fill the hole at the tailpiece end of the dowel and then re-drilling a new hole slightly lower. Doing that in addition to shimming might relieve some of the stresses.
Bill Rogers (Moderator)
I agree with pasdimo. I’ve had a credit-card shim on my Essex Concert Grand for 30+ years with no problems.
I've seen a number of dowel stick banjos (and good ones like vintage Fairbanks / Vegas) where the rectangular hole in the rim has been enlarged upward, where there has been a cut-out made in the top of the dowel stick where it goes through the rim, and both. Also where the hole through the rim at the tailpiece end has been elongated upward, even a second hole drilled and the mortise where the tailpiece end of the dowel stick fits into the rim moved up, all to allow some neck adjustment so a credit card or something could be added as a shim.
This of course "works" and as a down and dirty fix on your own banjo it's just fine. But these are amateurish things you wouldn't want to do if someone was paying you for a repair, or if you were paying someone to repair your old Vega.
About the dowel stress, you can consider the Weymann neck adjustment system, it works... bending the dowel. I never heard about more breaks on these banjos.
Here's the heel of a snazzy Fairbanks-Vega #9 on which the dowel had been seriously messed with—you can see the crack above the dowel stick where the neck halves are separating from the ebony center line. These old banjos were made with animal glue. I'm not saying the heel was cracked by forcing the dowel into an unhappy position, because I don't know what caused it, but it's cracked and bending these dowels out of their neutral positions can't be helpful.
I too have seen some crude hacking done to the rim mortise, tail bolt area, and notches cut into the top of the dowel.
To shim the heel anything over the thickness of a business card will mean something has to be done to prevent the stress, but cutting a notch in the top of the dowel is probably the worst of these approaches as it weakens the wood directly in front of the hole where pressure is applied on the brace pin, an can split the dowel.
I saw one banjo that had the top of the dowel chopped out, or maybe chewed out from the look of it, and had been shimmed with what looked like a piece of Popsicle stick which was a good deal thicker than what I have usually seen for a shim, but that banjo was an old cheap junker anyway, and the Jerry rigged fix did make it playable.
As Ken said, shimming will work, but it is a quick and dirty way to avoid re-setting the neck, and a properr re-set is how it should be done especially if it is a fine old banjo like a Fairbanks or Vega.
Edited by - OldPappy on 04/03/2020 08:54:31
Thanks everybody for your input to my question. Much appreciated.
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