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Jan 23, 2021 - 10:48:32 AM
2534 posts since 6/19/2008

I have these two rims & resonators, apparently Ludwig, I want to build into bluegrass banjos. They both take 10 3/4" heads, and are top tension rims drilled and tapped for tensioning screws. My question is, what is the original thread size for the screws. I tried a 6-32 screw and it went well into the first rim, but not so well into the second.

Rim one:




Jan 23, 2021 - 10:49:20 AM

2534 posts since 6/19/2008

rim 2 (I suspect this is lower end, or maybe not Ludwig at all, but still good quality cast brass):




Edited by - Jonnycake White on 01/23/2021 10:50:34

Jan 23, 2021 - 12:06:02 PM
likes this

13389 posts since 6/29/2005

If it's Framus, it would be metric.  If it's Ludwig, it would probably be the same thread as drum bolts.  You could google drum bolts and probably find the thread pitch.

Jan 23, 2021 - 7:37:42 PM

2280 posts since 2/7/2008

Drum bolts are 12-24

#6 is pretty close to 3.5 mm

Edited by - Quickstep192 on 01/23/2021 19:40:09

Jan 24, 2021 - 9:25:05 AM

2534 posts since 6/19/2008

3.5 mm = 1/8" = #6 machine screw size. Unfortunately, the thread pitch (number of threads per inch or per centimeter doesn't seem to be right for rim #2, so if I can't find a metric screw that fits, I'll probably just drill out the threads and go with a normal hook and nut on that rim.

The first banjo I played was a borrowed Framus, and it was a top tension IIRC. The rim was different that this one, though - I remember it had a grill made from aluminum in place of the flange, but I don't know what the tension bolts threaded into.

Jan 24, 2021 - 9:17:04 PM

2280 posts since 2/7/2008

Those are really cool!
 

You're right, the thread pitch on the M3.5 metric bolt would be different from an imperial 10-24 NC or NF

I'm planning a top tension banjo myself and plan to use socket head cap screws.

Here are some in M3.5

fastener-express.com/m3-5-x-6-...y-20.aspx

Edited by - Quickstep192 on 01/24/2021 21:19:11

Jan 24, 2021 - 9:36:19 PM

2280 posts since 2/7/2008

quote:
Originally posted by Quickstep192

Those are really cool!
 

You're right, the thread pitch on the M3.5 metric bolt would be different from an imperial 10-24 NC or NF

I'm planning a top tension banjo myself and plan to use socket head cap screws.

Here are some in M3.5 it seems you could use any size socket head cap screws if you re-threaded. Stainless looks nice against chrome or nickel. 

fastener-express.com/m3-5-x-6-...y-20.aspx


Jan 30, 2021 - 7:05:29 PM

2534 posts since 6/19/2008

Well I ordered the M3.5 x .6 bolts from fastener express. I hope they fit! I know the M3 bolts are too small and the M4 bolts are too big....

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