Stewart-MacDonaldEverything for building and repairing stringed instruments!
Your order cart Your order | Account | Saved list
Sign in
Email
800-848-2273, 9AM-6PM EST, M-F
Home Free catalog Quick order International Customer service

Home : Trade Secrets Archive : Issue 9, Straightening the neck on a 1914 Gibson mandolin
Trade Secrets NEWSLETTER
Email a friend









 Processing...







Treasure from Grandma’s attic:
How we got this mandolin’s
gnarly old neck to play again!

This beauty is a 1914 Gibson F2 that recently came into my shop. It was built with hide glue, and after 90-plus years every joint is still clean and tight. It’s fit as a fiddle... or mando... you get the idea. But the neck was bent like a banana. Here's how we fixed it.

Dan Erlewine signature Dan Erlewine, December 14, 2006
Getting Grandma’s mandolin playing again

Did you know these early Gibson mandos had no truss-rods? Instead, they inlaid a strip of maple in the mahogany neck. (The mahogany might actually have been stronger without the maple!) An adjustable truss rod would have kept the neck straight over the years, but they had yet to be invented back in 1914.
Photo: drill bits compared
Step 1: Pickguard off
This old mandolin was structurally sound, but it wasn’t playable: a century of hot summers in an attic had fatigued and warped the neck, which had curved into a nasty up-bow.

With a seam separation knife I coaxed the pickguard off the rusted support pins. Then I heated the fingerboard to loosen the glue beneath it...
Photo: grinder setup 1
Step 2: Fingerboard off
My bending iron supplied the heat (180°, monitored with a surface thermometer). Don MacRostie loaned me a neat gizmo for heating fretboards: a 1/4" piece of aluminum that has been slotted to straddle each fret. Straddling the frets, the aluminum contacts the board to give uniform heat.

It took 10 or 15 minutes of heat to soften the hide glue. I removed the mandolin from the heater and started working under the fingerboard extension with bridge/fingerboard removal knives. These thin, flexible blades slip into the slightest possible gap in a glue joint.
We've just created a new line of quality affordable mandolin tuners. Elite Mandolin Tuners are good looking, smooth working, and so new that their boxes haven’t even been printed yet! As a Trade Secrets subscriber, they’re available to you now, before others hear about them: see them now on our website!
$60.98 - $70.94 Buy Now
Photo: grinder setup 1
I use these knives two or more at a time, sliding one under the other, “leap-frogging” my way along the seam. One thing to be careful about: these blades are so thin they can slide into the wood and start separating the grain. Watch closely to be sure you’re separating the glue joint and not splitting the wood.
Photo: grinder setup 1
Step 3: Add a carbon
fiber neck support rod

Erick Coleman, StewMac’s Tech Support Director, worked with me on this job, and he carefully clamped the neck into a perfectly straight position, mounted on a workboard. Here's how the peghead was clamped.

Photo: grinder setup 1
With the workboard/neck setup on our milling machine, Erick routed a channel for a carbon fiber rod. A year ago, I would have done this with our precision router base, but I recently acquired my first milling machine, and I’m having a ball with it!
Photo: grinder setup 1
With the neck still clamped to the workboard, we glued in a carbon fiber rod using slow-set epoxy. Green masking tape keeps the neck’s flat surface clean (no glue overspill).

We let the epoxy cure overnight, and in the morning we had a dead-straight neck, ready for the fingerboard. We put new frets into the fingerboard before installing it, but we’ll leave that story for another Trade Secrets!

Problem-solving products mentioned above:
Photo: Bending Iron Photo: Surface Thermometer Photo: Seam Separation Knife
Bending Iron
Controlled heat bending form for guitar, mandolin, violin and dulcimer sides.
Surface Thermometer
A compact 50-500 degree F. thermometer that can be placed directly on the flat top of a heating iron to monitor the correct temperature.
Seam Separation Knife
The ideal knife for removing tops, backs and fingerboards from most instruments.
Buy Now
Buy Now
Buy Now
Photo: Bridge/Fingerboard Removal Knife Photo: Carbon Fiber Neck Rods Photo: Stewart-MacDonald Epoxies
Bridge/Fingerboard Removal Knife
This wooden-handled flexible spatula is great for removing bridges, pickguards, and the fingerboard extension from guitars.
Carbon Fiber Neck Rods
Stronger than steel, carbon fiber rods can supplement an adjustable truss rod, and short sections can be installed to reinforce the base of a peghead.
Stewart-MacDonald Epoxies
High strength 2-part adhesives, both fast- and slow-setting. We have a black version, too (great for working in ebony).
Buy Now
Buy Now
Buy Now

Toll-free order line:   800-848-2273   9am-6pm Eastern Time, M-F



Your order | Your account | Trade Secrets E-mail Newsletter
Home | Free catalog | Catalog Quick Order | International | Customer service
Our guarantee | Shipping | Security & Privacy | Contact us
Site map | About Us | Employment
© Copyright 2014 Stewart-MacDonald
Your shopping is secure with VeriSign! Trusted Commerce