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Mar 8, 2021 - 7:13:44 PM

bFunk

USA

106 posts since 5/22/2009

Hi everyone,

I bought a 1970s Japanese-made Astro banjo for $80 as a project banjo. I've played for over 10 years, but never completely disassembled or done significant work on a banjo.

I want to convert it to a semi-fretless with nylgut strings, with the first fret at the 6th fret. I've removed the 1st-5th frets, and in the process a couple panels of the wood fingerboard fell off, and others got chipped (see pics).

Here's some measurements that might be helpful:
- distance from nut to 6th fret: 8 inches
- fret height = 0.0395 in / 1mm
- height of wood fingerboard panel = 0.041 in / 1.07 mm
- width of fingerboard: 1.134 in / 28.80 mm

I'm thinking maybe I should glue the wood panels back onto the fingerboard, and then get a 1 mm thick brass sheet (so the fretless part is the same height as the frets) that's 1.13 inches wide x 7 1/4 inches long. I chose 7 1/4 inches so the fretless part ends just a little beyond the 5th fret spot.

I could also take all the wood panels off, do the same thing except with a 2.07 mm thick brass sheet, to account for the height of the wood panels (in this case I would have to cut out a small 3/4 inch portion of a wood panel to fill in the gap between the end of the brass sheet and the 6th fret.

1. Does the math work out in terms of the dimensions I laid out?
2. What's the best way to get a brass sheet and have it cut to those dimensions?
3. Should I consider a different material/plan altogether?

The advantage of taking off the wood panels and putting the 2 mm thick brass sheet is that it would "fit" into the fingerboard space in the neck, while if I just glued the brass sheet on top of the wood panels it wouldn't be as well supported.

Thanks, grateful and excited to hear any feedback.

Best,
Bryce


Mar 8, 2021 - 8:16:02 PM

1113 posts since 1/9/2012

Different people end up being happy with all manner of modifications. Since you already embarked on DIY, a lot of the details depend on your skill level. I'd never tell someone what's "best" or "right," but I've got a couple of suggestions of things to consider: 1) will you like keeping the 6th fret? and 2) what about the weight of the brass?

1) When you normally play, do you often fret at the 6th? I'm more apt to slide up to the 7th if that's an option. (That depends on tuning and playing I guess.)

2) Estimate the weight of the proposed brass and subtract that of removed frets and wood (if any). Attach a small thing of that weight to the back of the tuning head of the instrument you regularly play. I think you'd find the 2mm brass surprising -- but maybe not.

Mar 8, 2021 - 10:16:18 PM

6 posts since 1/12/2019

Here are some pictures of a semi fretless Deering Goodtime I made. I glued a brass plate from the nut to the 5th fret. I used 0.050" thick plate to be flush with fret height. I would re glue the wood panels and glue the brass plate on top. This will save the 5th string nut on the 5th fret.
I also scooped the neck and put a brass plate on the peghead. I still need to replace the number 16 and 17 frets.

Have Fun
Brad




 

Mar 8, 2021 - 11:38:46 PM

bFunk

USA

106 posts since 5/22/2009

Looks good Brad. Where did you get the brass, and how did you get it cut to the dimensions you needed?

Mar 8, 2021 - 11:44:24 PM

bFunk

USA

106 posts since 5/22/2009

quote:
Originally posted by davidppp


1) When you normally play, do you often fret at the 6th? I'm more apt to slide up to the 7th if that's an option. (That depends on tuning and playing I guess.)
 


I don't often fret at the 6th fret, but I do at the 7th. I like to be able to pull off from the 9th to 7th in open G. I figure it'll be nice to have a full fret's worth of fingerboard to work with for these pull-offs, hence have the first fret be the 6th.

Mar 8, 2021 - 11:58:57 PM

AndyW

UK

742 posts since 7/4/2017

I'm assuming you don't already have a fretless banjo so ignore if I'm spouting rubbish.

If you don't play above the fifth much except for an occasional foray to the 7th and 9th then consider making it fully fretless.

You'd then have the ability to adjust the scale a bit by moving the bridge which will help the banjo 'fit' your fingers. Also you'd find it nicer to slide into 7th and 9th.

I find a little marker at the 7th makes it's reasonably easy to make the 'jump' in hand position that is required to get the tunes that jump about between 5th/7th/9th. It does require a little 'look' but then I'd imagine you'd look anyway jumping up there even with frets.

Mar 9, 2021 - 1:40:10 AM

bFunk

USA

106 posts since 5/22/2009

quote:
Originally posted by AndyW


If you don't play above the fifth much except for an occasional foray to the 7th and 9th then consider making it fully fretless.

You'd then have the ability to adjust the scale a bit by moving the bridge which will help the banjo 'fit' your fingers. Also you'd find it nicer to slide into 7th and 9th.


Thanks for the input Andy, appreciate it. As far as moving the bridge around, how does that affect the tone?

Mar 9, 2021 - 3:28:07 AM

267 posts since 4/14/2014

quote:

Thanks for the input Andy, appreciate it. As far as moving the bridge around, how does that affect the tone?


It can have huge tonal changes, as you can place the bridge wherever on a fretless. You could place the bridge dead-centre for the darkest sound or very near the tailpiece for something brighter. Because you don't have frets to worry about, bridge placement is wide open, though you will have to adjust your fingers to intimate differently with the different placements. This bridge freedom isn't possible on a semi fretless when you use the fretted area of the neck. 

Mar 9, 2021 - 4:09:16 PM

6 posts since 1/12/2019

I got the brass plate on ebay from seller metalremnantsinc.  I cut it to size on a sheet metal shear and filed/ sanded it smooth after I glued it to the fret board. 
This ebay seller has remants of all shapes and sizes of brass.  You might get lucky and find they have the size you need or contact them and tell them what you need.  If that doesn't work you will need to find a sheet metal shop to shear it or try to cut it yourself with a fine blade hacksaw.  You can cut it yourself but it won't be straight and you'll have a lot of filing to do.
 
quote:
Originally posted by bFunk

Looks good Brad. Where did you get the brass, and how did you get it cut to the dimensions you needed?


Mar 10, 2021 - 2:38:48 PM

bFunk

USA

106 posts since 5/22/2009

Hey Brad,

Thanks so much for the recommendation of Metal Remnants. They responded super quick to my emails. They do custom orders, even for small pieces. I just ordered an 18 gauge and 20 gauge sheet, each at 1.125" x 7.25" dimension, for $11 and $13 respectively. Seems like a great price.

Best,
Bryce

Mar 10, 2021 - 3:23:53 PM

6 posts since 1/12/2019

Excellent!!! Yea that’s a great price for material and custom cutting. I think they are in Utah and the shipping is fast to California. I loaded two more pictures. One is the peg head. I used a thinner plate for that. 0.040” I rough cut it with hand tin snips and drilled out the tuning peg holes. After gluing it I sanded it flush with a dremel sanding wheel. The other picture is a side view of the neck. You can still see the fret slots from where the frets were. That is a good reference for finding notes if you get lost. I am able to find single melody notes fine but some of my chords sound a bit muddy on the fretless part of the neck.

Have fun!
Brad




Mar 10, 2021 - 3:29:38 PM

bFunk

USA

106 posts since 5/22/2009

You got an armor-plated banjo. I have almost no tools, so I'm not that ambitious.

When you glued the brass to the fingerboard, did you "rough up" the side of the brass that was getting glued with some sandpaper? My roommate suggested that would make the glue stick better.

Mar 10, 2021 - 3:47:46 PM

6 posts since 1/12/2019

Yes you need to rough up the side you are gluing to the fret board. Rough sandpaper will work. I used Gorilla clear grip contact adhesive. You also need to clamp it with small wood clamps for about 24 hours. You can get these at Walmart or Amazon for about $5 a piece. You need two.

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