Neck/Action reset on a 1923 Washburn Style A banjo

[Jerry Ryan]

I have a 1923 Washburn Style A Tenor banjo. The playing action is too high even with a 1/2" bridge. Everything about the neck assembly indicates that I would need to modify (cut) the slot or the neck itself where the neck enters the pot to raise the neck 1/4" + to get the playing action I want for playing Irish tunes.

BUT I really don't want to take a saw to it.

Jerry

[Greg Mirken]

No, that's not how you change the neck angle on a banjo. You need to remove the tailpiece bolt and loosen the neck mounting hardware so that you can pull the neck 1/8 inch or so away from the rim. Then fit a shim between the rim and the heel, as high as you can- either against the rim (preferred) or against the tension hoop. I'd start with 1/32" thick. Trim it so it doesn't stick out and tighten everything back up. That neck mount should allow you to squeeze the heel all the way tight to the bottom of the rim, with the neck now angled back a degree or two.

[Jerry Ryan]

Thanks!  I had a 1/16" piece of wide binding that matches the neck binding, inserted at top along the rim, fretboard joint. Put it back together, I was even able to bring the neck up almost 1/16" and put it all back together and with the the 1/2" bridge in place...the action is perfect!  Thanks!

[Bruce Vernon]

How do you calculate the thickness of the shim for different scale lengths? That tenor banjo probably has a short scale/neck. I have an old S.S.Stewart with a 27 inch scale. There's math involved here and I don't remember enough of whatever it is to find the right thickness. 

[Robbie Collins]

You could try the standard neck reset formula since taking off x amt on the bottom is the same as adding x amt to the top in terms of resulting angle but, since the shim moves the neck away from the body, the bridge will move towards the neck.

[Ron Ellison]

Isn't this just a matter of basic equivalent ratios? String length and heel depth are the two long values, the shim thickness and the action difference are the two short values.

If I remember correctly, if A and B are the long values and C and D are the short values

A:B=C:D

AxD=BxC

Jiggle the formula around to find the unknown value (shim size).

To be honest I'd just use trial and error.