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Sep 2, 2019 - 5:38:48 PM
955 posts since 4/13/2017

Ok, so I haven't even gotten my current build ready for assembly (no where near it lol), and I'm already planning my next one.

I'd like for my next one to have an extended fingerboard like Noam Pikelny's banjo, but I have some questions about that...

I done a little math of my own...if I want the lag bolt in the neck, and the rim rod holes to be in the same spots as a normal banjo, could I add an extra 3/8" of height to the top of the heel, raising the fretboard above the plane of the head? The measurements are shown in the picture below...

Ok, so a standard banjo neck, set up for a 5/8" bridge, 1/8" high at the 12th fret, the neck angle is 3 degrees, correct?

If that's the case, I would be raising the level of the fretboard by 3/8", and therefore, I would need a bridge that was 1" tall, right? That is if I cut the heel to the standard 3 degrees. But what if I don't want that ridiculously tall bridge? I would need to change the heel angle.

Here's the question: If I want an action of 1/8" above the 12th fret, using the setup with the extended and raised fingerboard, what angle do I cut my heel to to still use a 5/8" bridge?


Sep 3, 2019 - 6:45:03 AM

1466 posts since 6/2/2010

Blue,

I can figure out the exact angle you would need using trigonometry but first need your scale length and the distance from the neck/pot joint to your bridge.

Thanks,

Paul

Sep 3, 2019 - 11:25:06 AM

12340 posts since 6/29/2005
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You have to make an accurate drawing in scale showing:

(a) the desired bridge height and position

(b) the desired string height from the fingerboard

(c) the desired string height from the head

Get the drawing to accurately depict all those specifications and the angle where the neck meets the pot can be measured from the drawing.

Essentially, every aspect of how you build the pot can be determined in the drawing, which becomes a template.

Edited by - Ken LeVan on 09/03/2019 11:28:20

Sep 3, 2019 - 12:58:13 PM

955 posts since 4/13/2017

quote:
Originally posted by maneckep

Blue,

I can figure out the exact angle you would need using trigonometry but first need your scale length and the distance from the neck/pot joint to your bridge.

Thanks,

Paul


Scale length is 26 1/4", and I dunno about the distance of the bridge from the pot and neck joint...

Sep 3, 2019 - 12:59:44 PM

955 posts since 4/13/2017

quote:
Originally posted by Ken LeVan

You have to make an accurate drawing in scale showing:

(a) the desired bridge height and position

(b) the desired string height from the fingerboard

(c) the desired string height from the head

Get the drawing to accurately depict all those specifications and the angle where the neck meets the pot can be measured from the drawing.

Essentially, every aspect of how you build the pot can be determined in the drawing, which becomes a template.


I tried that, but couldn't get things to work out right...

Sep 3, 2019 - 1:43:29 PM
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12340 posts since 6/29/2005
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quote:
Originally posted by Blue20Boy17
quote:
Originally posted by Ken LeVan

You have to make an accurate drawing in scale showing:

(a) the desired bridge height and position

(b) the desired string height from the fingerboard

(c) the desired string height from the head

Get the drawing to accurately depict all those specifications and the angle where the neck meets the pot can be measured from the drawing.

Essentially, every aspect of how you build the pot can be determined in the drawing, which becomes a template.


I tried that, but couldn't get things to work out right...


If you can't get it to work out right in a drawing, I guarantee it won't work out in real life, then you will have wasted a lot of time and material.  paper and computer time is cheap compared to building something that doesn't work.

After a drawing, you could make a rough model from cardboard or something like that.

Sep 3, 2019 - 2:43:52 PM

1466 posts since 6/2/2010

Ken is correct. To get an exact number you need all of the info.

Here is an estimate based on 26 1/4 scale with the bridge being 2/3 across the top.

The angle should be approximately 1.865 degrees. Not sure it is possible to cut something that accurate without some precision machine though.

Sep 4, 2019 - 3:36:05 AM

955 posts since 4/13/2017

quote:
Originally posted by maneckep

Ken is correct. To get an exact number you need all of the info.

Here is an estimate based on 26 1/4 scale with the bridge being 2/3 across the top.

The angle should be approximately 1.865 degrees. Not sure it is possible to cut something that accurate without some precision machine though.


Now let me ask you this...what would my bridge height be if I cut the heel to an even 2 degrees?

Sep 4, 2019 - 5:20:46 AM

1466 posts since 6/2/2010

11/16 inch bridge should work for 2 degree neck angle.

Sep 4, 2019 - 10:14:53 AM

1466 posts since 6/2/2010

Blue,

Rudy just posted a great post regarding neck angle/sled design. Make sure you read it - makes it easier to get exact action you want without worrying about exact neck angle cutting.

It also ties into what Ken says above regarding a scaled drawing of what you are building.

Paul

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