Top and back radius of j45 copy

Questions and answers for beginners. If you have a question, so do most other people.
jusbroacoustic
Posts: 17
Joined: Mon Oct 17, 2016 10:47 am
Location: Orangevale, California

Re: Top and back radius of j45 copy

Post by jusbroacoustic »

ok, thanks John! I will check it out.
sammyjit
Posts: 61
Joined: Fri May 22, 2015 7:43 pm

Re: Top and back radius of j45 copy

Post by sammyjit »

The fingerboard radius and the radius of the top don't really have anything to do with each other. The angle of the neck to the top does matter. I believe you can use whatever radius you want to for your top. However, your neck angle and your bridge location have to be adjusted accordingly after the top is in place. This angle is custom to different guitar designs for sound, intonation, and functionality.
MaineGeezer
Posts: 1711
Joined: Wed Aug 13, 2014 12:14 pm

Re: Top and back radius of j45 copy

Post by MaineGeezer »

Maybe some people can construct a guitar so the neck is at the correct angle to the body without any adjustments. I can't. When the time comes to install the neck, I spend some quality time with a straightedge, sanding blocks, a small chisel, and quite likely some assorted shims to get the neck aligned properly to the body by carefully shaving/sanding the heel of the neck where it contacts the guitar body.
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
tippie53
Posts: 7011
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: Top and back radius of j45 copy

Post by tippie53 »

to control the neck block I use screws and screw it through the mold to act as a spreader. This will hold the neck square to the mold. Then when I use my sanding dish I can set the angel pretty precisely. This makes setting a neck pretty easy compared to letting it float or using an inside spreader
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
sammyjit
Posts: 61
Joined: Fri May 22, 2015 7:43 pm

Re: Top and back radius of j45 copy

Post by sammyjit »

I hear you on that. I have had an instance where I was about to sand my neck angle into the top and noticed a lot of wobble that the neck block has in the mold. If you are using a Martin style block with the 90 fork that extra piece of wood adds more leverage to the neck block which can move the angle even more. There is enough wobble to screw up a neck angle by a huge margin. I ended up making some neck to tail block spreaders. They worked for the job being but the spreader was so long any inconsistency created a torque and the force wasn't linear. Screwing the neck block to the mold seems so much simpler and effective.

And yes, lots of time setting the neck. Lots of patience is required. Getting the neck angle on the body correct does help tremendously though. John's videos are very good in explaining the whole process.
Post Reply