stew mac

Neck Shimming Made Easy

I’ve written about neck shimming a while back, but the world of shimming has moved on and it’s worth an update.

Why would I have to shim a neck?

Two reasons:

  1. Even when you’ve lowered your bridge saddles as far as you can, your action is still too high.
  2. You want to purposely raise your bridge to get a steeper string angle over it. This can be helpful on Jazzmasters and Jaguars (where the strings generally go over the bridge at a quite shallow angle which reduces downward pressure and can cause hassle).

How would I go about shimming a neck?

Well, here’s how you would not go about it:

  1. By using Fender’s Micro-Tilt adjustment thing.
  2. By installing a popsicle stick, or similarly sized shim at the end of the neck pocket.

It’s my opinion that shimming in this way can contribute to and/or speed a hump/ramp/ski-slope condition at the end of your fretboard. This can mean fretwork to resolve so you’d prefer to avoid it if possible.

Check out my How To Shim A Bolt-On Neck article for a more in-depth explanation.

What’s the correct way to shim a neck?

You need to avoid any ‘air gaps’ between the neck and body. This means a ‘full-pocket’ shim.

That's a wedge-shaped piece of wood that will angle the neck backwards but will allow good solid contact between neck and body, with no gaps.

Now, if you’ve read that previous article, you’ll have learned what a pain in the butt it is to actually make these shims. It’s a fiddly job that used to be only for the bravest of shimmers.

Until recently.

Stewart McDonald have figured out a way to reliably manufacture full-pocket, wedge-shaped shims*.

Check it out.

You can buy a shims with different angles — a 0.25°, 0.5°, and a 1° wedge. The 0.5° should be enough for most jobs but it’s nice to have the option of something bigger (the bigger one is useful for the offset Fenders when you're deliberately trying to raise the bridge height).

The shims fit a standard neck pocket and even have a marked line to show where to cut for a squared-bottom pocket.

I’ve used them for the first time today and I’m a happy repair-guy. I’ve hated making these shims in the past and being able to buy them is one less source of stress.

When I originally wrote this article, only guitar neck shims were available. Now, Stew Mac has tapered bass shims too (and some 'blank' shims in case you've a weird sized pocket). 

Don't just use a short shim at the bottom of the neck pocket. Shim your neck with a full-pocket shim to prevent ramps/ski-slopes.

It's a bit difficult to see the 'wedge' shape of this shim bit it's thicker at one end and feathers to almost nothing at the other. This is perfect to properly shim a guitar neck. 

*It has been possible to buy ‘flat’ shims—a consistent thickness all along. You could use these to shim a neck but, because you’re not angling the neck, you need to add a much thicker flat shim to achieve the same result. It’s not the best solution. 

Fretting an Acoustic Guitar

When you're fretting an acoustic guitar, there's an added complication: The fingerboard extension (that bit over the body). 

Mostly, this part of the fingerboard is glued to the guitar top and usually has very little support underneath. You can't just start hammering frets in here without running the risk of badly damaging the guitar top or the bracing beneath. 

There are ways of pressing frets into this section but they're slow and a little clumsy. What I (and most repairers) do is to use a 'ballast' of some sort to absorb some of the hammer-blows' energy. This means using one hand to hold a relatively massive (as in mass rather than size) object underneath the fingerboard extension as you hammer frets home with the other. This works but is also a bit clumsy and a bit awkward.

Years ago, Taylor Guitars went a long way towards solving the problem. They used a cast-iron device they called a Fret Buck. The buck sat on the guitar's face and an internal 'foot' clamped up underneath the fingerboard extension to support it. Hurrah for Bob Taylor.  

For a while, you could even buy a fret buck. I know because I kept saying to myself, "I must get one of those. I'll put one in my next order." I didn't though. I kept forgetting or putting it off. 

And then they disappeared. 

No longer available. Anywhere. About six or seven years ago, they vanished. I continued with my contortions, wishing I had a third hand, while fretting. No biggie. 

Then Stew Mac worked some magic and began offering their own version a few months ago. Hurrah for Stew Mac. The Fret Buck's not an absolutely essential tool but it does make an awkward and potentially damaging job a lot easier and safer. 

And quieter. Hammering frets over an acoustic body is a noisy job and the buck soaks up some of that noise too. 

I'm quite fond of my fret buck. Should have got one years ago.  ;-)