Please educate me on 3/8 vs 1/2" tuning machine hole sizes

[james condino]

I'm primarily an upright bass player and builder, but I have an electric bass project as a bit of a distraction.

The basic idea is a well worn survivor 1960s body with a new fretless neck that I made specifically for an upright player. The fingerboard is an ebony upright bass fingerboard that one of my students made a little too thin (for an upright; still massive for a slab bass). It has a giant radius and sort of a hybrid feel with some internal carbon fiber and one of my titanium adjustable truss rods. Electric players may not understand it but I've had requests from upright players for that setup for decades. This is approx. instrument #350 for me so I have a good plan, plenty of experience, and a kick ass workshop. More later on the instrument details.....

I've been looking at commercially available tuners like the Hipshot and others and they tend to come in two styles- 3/8" holes and 1/2". Is there any real working difference beyond the fact that 25,000 different manufacturers have used different specs over the last 75 years? My tendency would be to go with the 1/2".

 

[MPU]

I don't see any functional difference. Whichever suits your headstock better is fine. Weight may be the only notable difference.

 

[Gilmourisgod]

Yep. Ive been using 3/8" where I can just for weight. The Fender style 1/2" post and big elephant ears just look clunky to me. The Schaller Rickenbacker tuners are a nice compromise, smaller ears with shorter tuner shafts and 3/8" posts, and run around $90 a set. The Hipshot are very nice, but actually not as light as Gotoh Res-O-Lite.

 

[Bruce Johnson]

Remember that 3/8 and 1/2 are the diameters of the posts, not the holes in the headstocks.

3/8 post tuners normally fit in a 1/2" diameter hole on the back of the headstock, and a 9/16" counterbore on the front, about 7/16" deep, for the bushing. However, most people just drill 9/16" through.

1/2" post tuners normally take a 9/16" hole on the back, and an 11/16" counterbore on the front for the bushing.

As far as the functional difference between 3/8" and 1/2" post tuners, the 3/8 tuners end up with a little bit lower (higher numerical) overall gear ratio, because of the smaller diameter post. A bit finer tuning resolution. And they are a little lighter weight.

It really comes down to whether you want the vintage Fender look of 1/2" posts, or not.

 

[41hzthunder]

Good information from Bruce! I would add that drilling some test holes in a scrap might help build confidence in fit and finish, especially if this is new to you. Its very hard to drill a smaller hole, once you've drilled a larger one, or even expand an existing hole without "chatter". I believe some tuning machines are metric. I purchased some Schaller machines that definitely required metric drill bits to get a good fit. Check the specs for your manchines carefully. Good luck and hope to see the finished work soon!

 

[Beej]

I want to know more about this bass What's the scale length?

 

[Big B.]

Bruce covered most of the factors but I'd also consider the strings you'll be using. The posts on the 3/8" tuners are pretty small and occasionally I've had problems wrapping larger diameter strings around them. B strings and flatwounds in particular. Roundwounds are pretty forgiving but you've worked on enough double basses to know how flatwound windings will bunch up if they are bent too far.

I recommend against boring a single size hole because the bushing is quite a bit bigger than the post itself. More than one of my early basses ended up with that hole partially visible around one of the tuners on the back of the headstock. Now I start by drilling through with a 1/16" bit. Using that as a guide hole you can use the proper diameter bit to drill for the bushing from the front and then use a smaller bit to drill the post hole from the back. This also gets rid of the slack around the post itself and helps hold the tuner in place. You will also eliminate any chance of tearout because you'll be drilling into each face.

 

[rudy4444]

I've never liked how tight the wrap is when using 3/8" string posts. The low strings always look like they need a larger post so the string wraps aren't displaced as the string wraps around the post.

Bruce is correct about many drilling straight holes for mounting 3/8" Hipshots, but it's easy to end up seeing the edge of the hole at the rear, and drilling the holes to 11/16" for the 1/2" Hipshots is even worse. Much better to drill stepped holes to eliminate that problem.

 

[matante]

I've never liked how tight the wrap is when using 3/8" string posts. The low strings always look like they need a larger post so the string wraps aren't displaced as the string wraps around the post.

Bruce is correct about many drilling straight holes for mounting 3/8" Hipshots, but it's easy to end up seeing the edge of the hole at the rear, and drilling the holes to 11/16" for the 1/2" Hipshots is even worse. Much better to drill stepped holes to eliminate that problem.

I think just about every modern bass, at all price points, has smaller size holes so I don't see how it can be an issue.

 

[J_Bass]

1/2 posts are better suited if you want to play with flats.

With 3/8, there is a risk of string breakage with some flatwound models, if the string wraps around the post after the silk.

 

[micguy]

The reason that 1/2 inch posts exist is largely because we're used to seeing the old Fender clunky tuners. I'm not sure why Leo chose to make those things so frickin' huge - no real reason for it. All my basses have Hipshot Ultralites, and all, save one where the neck came with holes for the 1/2 inch tuners, have 3/8ths post tuners. They work just fine, and yes, they weigh a bit less - a really light bass that balances is a good thing; light tuners are a huge part of making that work. On a 5 (or a 6) that's even more important than it is on a 4.

 

[JimmyM]

I'm primarily an upright bass player and builder, but I have an electric bass project as a bit of a distraction.

The basic idea is a well worn survivor 1960s body with a new fretless neck that I made specifically for an upright player. The fingerboard is an ebony upright bass fingerboard that one of my students made a little too thin (for an upright; still massive for a slab bass). It has a giant radius and sort of a hybrid feel with some internal carbon fiber and one of my titanium adjustable truss rods. Electric players may not understand it but I've had requests from upright players for that setup for decades. This is approx. instrument #350 for me so I have a good plan, plenty of experience, and a kick ass workshop. More later on the instrument details.....

I've been looking at commercially available tuners like the Hipshot and others and they tend to come in two styles- 3/8" holes and 1/2". Is there any real working difference beyond the fact that 25,000 different manufacturers have used different specs over the last 75 years? My tendency would be to go with the 1/2".

I have a bass with 3/8 inch Hipshots which also includes the Xtender. I also have them in the 1/2 inch version, And the only practical difference is when I use my favorite Dunlop strings, which are lower tension. With the 1/2 inch, I can only tune down to a sharp C using the Dunlops and the Xtender. With the 3/8 inch, I can turn down to a B. Otherwise I think they're just as functional as any. Schaller's been making Tuners with much smaller post for decades and nobody seems to complain about them.

 

[Doner Designs]

I like the big ones on an inline Fender style headstock. On 2+2 the smaller ones are a better fit in my opinion.

 

[J-Bass RMR]

I like the larger diameter posts - especially if you are using heavier gauge strings.
Like many things on TB, it's just personal preference.

I'm not sure why Leo chose to make those things so frickin' huge

He didn't.
They were one of the few, if not the only part that already existed 70 years ago; Upright Bass tuners adapted to the new Precision Bass.
And they turned in the right direction!
(obviously, I started on upright)

 

[2F/2F]

1/2" = a traditional looking post and bushing, more weight, and a slightly different real-world gear ratio "feel" (though usually the same gear ratio on paper).

3/8" = lighter, slightly different feel, and a more open looking peghead face.

According to the Hipshot Website, each 3/8" tuner is 0.24 oz. lighter than the equivalent 1/2" version. In other words, you lose just shy of an ounce off the headstock by using the 3/8" version. In other words, nothing worth mentioning.

Therefore, IMO, go with the one that you think looks better with your headstock design.

 

[Ceiba Groove]

Hello I got into this thread because I'm replacing a neck but the neck that I just bought says it has 18 mm tuner holes but the headstock I am replacing got this machine head pegs:
Allparts 4-in-line Chrome Import Bass Tuners TK-7947-010 | Reverb
which have these specs:

20:1 gear ratio. chrome set of 4 with headstock bushings and mounting screws. Fits Fender Squier Bronco and other import bass models.
Base plate 39 x 17.6 mm.
Screw hole spacing 10 x 33.5 mm center to center.
3/8 inch diameter post.

So my question is, will I have to replace the machine tuners or may I use the ones I got from the old headstock, by just adapting or doing some bushing?, thanks

 

[KidAmnesia]

Hello I got into this thread because I'm replacing a neck but the neck that I just bought says it has 18 mm tuner holes but the headstock I am replacing got this machine head pegs:
Allparts 4-in-line Chrome Import Bass Tuners TK-7947-010 | Reverb
which have these specs:

20:1 gear ratio. chrome set of 4 with headstock bushings and mounting screws. Fits Fender Squier Bronco and other import bass models.
Base plate 39 x 17.6 mm.
Screw hole spacing 10 x 33.5 mm center to center.
3/8 inch diameter post.

So my question is, will I have to replace the machine tuners or may I use the ones I got from the old headstock, by just adapting or doing some bushing?, thanks

You should meassure if the outer diameter of your bushings is also 18 mm. But judging from the reverb pic, it's quite smaller. 18 mm is about the diameter of the hole you need for 1/2" post, Fender style tuning machines, so I would get a set of those. But you could also plug the existing holes and redrill them with a bit the size of your tuners.