Loose Tuning Machine Bushings

How do I keep the small bushing (ferrule) that fits around the tuner's post from falling off?

You may have already noticed that some tuning machine bushings screw to the tuner while others simply press into the holes in the peghead. Well, they're suppose to anyway. Unfortunately loose press fit tuning machine bushings can fall off easily when the strings are removed. With any luck it will hit the floor and roll, usually right to the spot you look for it last!

For screw on bushings we merely tighten them with a nut driver (10mm is a very common size), but for press fit bushings we must address the size of the hole in the peghead.

Comparison of Tuners Using Screw On & Press Fit Tuning Machine Bushings

Common Problems:

• The hole was drilled too large for the bushing to fit securely
• When replacing the tuning machines the replacements are slightly smaller than the original
• Humidity levels have changed and the ferrules have become loose

Martin guitar with Butterbean tuners and loose bushings.

Don't Glue The Bushing To The Peghead

My technique for securing the loose bushing to the peghead does not include gluing it in hole. Why not? First and foremost I simply don't want to alter the instrument. An unsuspecting repair person may wish to remove the bushings in the future, not expecting them to be glued in, and do serious damage to the peghead if precautions are not used.

For Slightly Loose Bushings

When a bushing is only a little loose, layering the sides of the hole with superglue can decrease the size of the hole just enough to allow the press in bushings to fit securely. I call this "padding". 

I apply Hot Stuff Super T medium viscosity superglue in very thin coats until it's thickness has decreased the size of the hole. Because the glue changes the size of the hole, it is not unusual to go from having a hole that is too large to one that is a little too small. If this happens I use a peghead reamer to size the hole just as I would on new construction.

Caution!

While this is a simple repair it is easy to make a mistake that can turn this into a major headache.

Superglue drips easily! A drop of superglue on the finish can turn an otherwise quick and easy repair into a time consuming finish repair. 

Using too much glue or very thin glue may cause it to run down the sides of the hole and pool along the backside of the peghead.

Installing the ferrules before the glue has dried completely could cause the bushing to stick when attempting to test fit.
Obviously, you may wish to have the repair done for you if you are uncomfortable with the idea of practicing this on a valuable instrument.

Glue "pads" the sides of the hole to slightly decrease it's size. Allow it to
cure before installation of the bushings.

For Very Loose Bushings

While that technique is ideal for machine head bushings that are a little loose, those that fit so poorly that they move side to side require more effort. This is usually only a problem if one is installing replacements that are not replica's of the original or when the guitar has had multiple sets installed thru the years which have damaged the peghead hole. In these instances plugging the holes and re-drilling is usually necessary.

This vintage Gretsch Synchromatic guitar has been thru several tuner replacements
leaving the peghead holes oversized and peppered with screw holes.

For more information on Tuning Machine Replacement, visit our site.

 

Neck Resets - Glue Nightmares

Gluing Necks on Acoustic Guitars

Today I am addressing guitar necks that use dovetail joints. 

Sliding a Martin D-18, dovetailed neck out of the neck block after steaming.

What Holds the Neck On?

While glue obviously keeps the neck from coming off, dovetailed joints are designed to slide together, wedge and "lock". When a dovetailed joint is not shaped or fit properly the glue is being asked to do far more work than intended. On many occasions I have seen a loose neck joint blamed on glue failure when in fact, a poorly fitting dovetail was the underlying cause.

I have had quite a few people bring me acoustic guitars that have loose necks. Understandably they are hoping for an easy and cheap fix ...like simply gluing the neck back on. Unfortunately that is rarely the case when doing the job professionally. Dovetails must be shimmed and fit to insure the joint is locking. Simply adding fresh glue to a loose or sloppy dovetail joint would not be a professional repair. (In more transparent language ...it isn't anything I would offer to do.)

Glue Nightmares


Between the chisels and the reamer lay a bottle of Tylenol. I'm going to need it.

Ack Ack! A Martin neck block filled with epoxy.
Yellow lines = this is where the dovetail locks and glue is applied.
Red line = this open area has been filled with epoxy making removal a nightmare.

Above you see a neck pocket that has been completely filled with adhesive, and not just any adhesive ...it was epoxy. After steaming the neck the traditional way I quickly realized it was having no effect. The neck joint only takes a couple of minutes to loosen with steam, mysteriously, this one was still securely set and showed no sign of yielding.

Necks should be glued using water soluble adhesive only. This would include Titebond regular (woodworker's glue) and Hide glue.

Because there was evidence that this fingerboard extension had previously been removed I had my suspicious and removed it to have a looksie.

Another fingerboard which had been 
sawn thru at the 14th fret.

Sawing Thru Fingerboards? That Can't Be Good

Exactly! And that's not the way we do it today. However, once upon a time a far more conspicuous and somewhat destructive method of removing guitar necks was sometimes used. Instead of simply drilling holes down thru the fret slot into the joint, the fingerboard was sawn in half at the 14th fret. This allowed the fingerboard extension to be removed and set aside, exposing the dovetail joint.

While this made the joint physically (and visually) accessible it meant the fingerboard would have to be repaired. And when they were bound it was far more obvious as seen in the picture to the right.

Although this is obviously not recommended it is still a part of guitar repair "history" and something I have seen several times.

Oh Goodie, another one!

The previous repair person had used this method and upon reassembly opted to fill the neck block with epoxy. Oh man ...why me?

Just to reiterate ...a locking dovetail requires very little glue. When I see something like this I assume the individual was trying to use adhesive to keep everything together instead of properly fitting the joint.













Fitting The Dovetail

The arrows point to mahogany shims that I have glued into the neck block where it will contact the neck's dovetail. This (and the fingerboard extension) are the only area's that will receive glue.

New mahogany shims have been glued into the neck pocket and
sanded to provide a locking fit for the dovetail. 

Neck Shims

Shims are required when resetting acoustic guitar necks so the joint can be sanded to fit properly after removal. When a neck is removed from an instrument all old glue is sanded away and the contact surfaces are smoothed, this process removes wood making shims necessary. Even on new construction, shims are often present.

Once the shims are glued in place I begin the sometimes arduous task of sanding and test fitting. I still prefer good old pencil lead as it allows me to see where my joint is rubbing, sand high spots and insure good coupling. Instead of merely placing shims at the tip of the dovetail I create a locking joint which mates from top to bottom.

For more details, you can read my acoustic guitar Neck Resetting article here.