drilling tuner holes

[J.Sloan]

When drilling the tuner holes is it better to drill from the front of peghead or back? I have the Stewmac tuner hole drill guide and it recommends drilling from the back of peghead, which I have done on my last 4 mandolins. However, I've noticed other kit/parts companies that recommends drilling from the front of peghead. Has anyone used both methods and found one to be better?

Also, I thought that I would mention....to anyone that it may help.....if you buy the Stewmac golden age A tuners, make sure the buttons are not loose. I had a buzz on my last A5 that was really tough to locate. Turned out that all of the buttons were slightly loose and could be pulled off with little force. A little CA glue solved the problem!

[sunburst]

If the peghead is even thickness, drill from either side (be sure to back up the exit surface to prevent "blowout").
If the peghead is tapered (as Loar and many others have historically been) it is best to drill perpendicular to the front of the peghead so the bushings fit flush to the front of the peghead. For a drill jig like Stewmac's, that means drilling from the front. For a jig like mine, that means drilling from the back.

[Graham McDonald]

I like to drill a 1/16" pilot hole from the back, and then drill to size from both sides. A Forstner bit a little less than the diameter of the ferrull (is that spelt right?) halfway through from the front is good to avoid tearout on the front veneer and then a slightly smaller bit from the back to finish off. A violin peg reamer from the front is good to get the taper to snugly fit the ferrulls, which tend to be of slightly different sizes from different manufacturers, otherwise a drill bit so the ferrull sits slightly proud of the veneer (1/16" or so) so it can be firmly seated with a vice or a clamp.

Cheers

[Jim Hilburn]

This is a road John and I have been down before.
If you plan to use modern tuners, meaning modern bushings, then I believe you should have an evenly thick peghead and it won't matter which side you drill from. The bushings used in older instruments were as much ornamentation as serving a purpose and would accommodate the tapered peghead but modern bushings will only give a couple of degrees leeway but ideally work best when installed straight up making a flush surface for the tuner shaft to bear on.
I've always drilled from the back.

[fscotte]

Drill the peghead before you taper it. And even if you have "blowout" you can sand it away if you finalize it's thickness after you drill the holes.

[Hudmister]

The Forstner bit technique works for me to make a perfect cut from the front. I like your use of the word ferrule (ferrull), since bushing seems to be more popular in the US. I've always called it a ferrule too.

Cheers

[Jim Hilburn]

Drilling from the back, you would have the peghead clamped tightly onto another piece of wood and would not have to worry about a "blowout".

[Graham McDonald]

Of course, a bushing (DOH), and thank you for the spelling correction.... I know about clamping the face of the head to another piece of wood, but I just think it is a little safer to drill the bushing mounting holes from the front. My heads are not tapered, so that is never a problem.

Cheers

[Jim Hilburn]

Graham, I just use another approach. Using the Stew Mac drill guide you have to use a 1/4" bit. Once I have those holes I use a piloted reamer like SM sells for Waverly's. I also don't enlarge the hole all the way through, just enough for the bushing to fit.

[Jim Adwell]

I drill peghead holes from the front with Forstner bit and ream to size.

Are pegheads tapered just for looks or is there another reason?

[sunburst]

Are pegheads tapered just for looks or is there another reason?

One (might be considered two) other reason. The base of the peghead, the part where the truss rod pocket usually is, can be made thicker and therefore stronger while the tip of the peghead (where strength is less important) can be made thinner and therefore lighter.

[Michael Lewis]

I drill from the back but only because I disassemble the machines and mount the base plates, and with a transfer punch mark the centers of the string post holes. Then remove the base plates and reassemble the machines, and drill the holes with a brad point bit.

I found too much 'tolerance' when using the StewMac drilling guide. When using high precision machines like Waverlys the holes in the headstock must be very accurate, so I use the holes in the base plates as the reference.

[HoGo]

If the peghead is tapered (as Loar and many others have historically been) it is best to drill perpendicular to the front of the peghead so the bushings fit flush to the front of the peghead.

I'd add that in this case you need to make sure there is rather loose fit of bushings on the posts as they will be at slight angle when installed. Older Schallers with those long tight fitting bushings made this impossible without either enlarging inner hole or shortening the bushing.
And I'd drill bushing-sized holes all through the heastock and not "stepped" holes like SM shows as the tuners may bind against wood on the bottom of headstock. And it is much easier to extract bushings by pushing with stick from below.

[Jim Hilburn]

Seems to me that an equally thick PH is a small and nearly in-noticeable compromise to the "original" to make sure your tuners work correctly.

[sunburst]

I'd add that in this case you need to make sure there is rather loose fit of bushings on the posts as they will be at slight angle when installed.

I've heard that before, but perhaps you remember the early version of Waverly's "precision bushings". They were quite a bit longer than the ones they supply now, and quite a bit longer than the Schaller bushings, with a close fit on the posts. I had no problem using Waverly tuners with those bushings in tapered pegheads. The angle of the post into the bushing is not extreme when the peghead is tapered, and any bushing I have used with any tuner has had plenty of clearance to accommodate the angle.
Though I can use any bushing (determined through experience), I prefer and use the light weight "20s style" thin bushings with holes drilled through the peghead with no step.

In order for there to be clearance between the post and the bushing (so the tuners can be installed in the bushings and be able to turn), the diameter of the hole in the bushing must be larger than the diameter of the tuner post. In theory, the two circles (post and hole) will intersect and make contact at only one point no matter how close or loose the "fit" between tuner post and bushing. String tension will pull the post against the bushing in the direction of the nut, and it will make contact at a point there, near the front surface of the peghead. As long as the bushing hole is not so small that the slight angle of the post (resulting from the tapered peghead) causes interference at the other end of the bushing hole to the opposite side, there is no problem, and as I said, no bushings that I've tried caused a problem.

[Jim Hilburn]

The point I'm making is that in a perfect world it is better to have the shaft bearing against the entire length of the bushing as intended rather than having it go through at an angle and bearing only on the upper edge.

[sunburst]

I suppose we can (once again) agree to disagree. It seems to me that, in a perfect world, having the bearing surface in the bushing as close to the front of the peghead as possible is better. The post then has two bearing surfaces; the tuner plate at one end and the bushing near the other. Perfect alignment from tuner plate and all the way through the bushing seems unlikely to me in the real world, especially when 4 of them must align so well, and each has string tension pulling on the unsupported end "trying to" lever the post over the front edge of the bushing.

[sunburst]

...in thinking about this further, for pure functionality, perhaps it would be better to have a tuner plate on the front of the peghead as well as the back; holes in identical positions. Alignment would be assured, bearing surfaces would be equal front and back... but it would be heavier than bushings, and probably, in most opinions, not particularly attractive... though there are those who like pearl, shiny metal, and/or decorated truss rod covers...

[Larry Simonson]

As I see it, we want the tuner's plate parallel with the bottom of the HS and the bushing's seat to be parallel with the top of the HS which is not possible on a tapered HS. I also think that if tuner installation was done by a picky machinist, she would cut a circular flat parallel to the back of HS on the top of the HS at each hole allowing the bushings to fit properly. If this was a huge enough business a piloted drill with both bushing's diameters would exist, I think. Maybe someone out here has machined such but I have not been able to find one.

[sunburst]

...Ialso think that if tuner installation was done by a picky machinist, she would cut a circular flat parallel to the back of HS on the top of the HS at each hole allowing the bushings to fit properly...

The bushings a machinist would likely be using would be a different situation, assuming he/she is working on machinery as we normally think of machinery. A machine bushing has a specified tolerance for fit, and it's generally a pretty close fit, often determined by engineering, considering material, temperature range and so forth. If he/she was that picky, said machinist might well reject the tuner plates and their bearing surfaces and rethink the whole situation.
FWIW, folks have cut flats similar to what you describe when they've made pegheads using "out of the box" designs without flat parallel (or nearly parallel) surfaces.
Certain tuners, notably banjo type tuners, are designed for parallel surfaces and some can be damaged if the front and back surfaces of a peghead are far enough out of parallel, but the 4-on-a-plate type tuners we (have to) use for mandolins have no problem with the situation. As I've already said, the fit is loose enough to easily accommodate the peghead taper even with the longest, closest fitting bushings I've see and used.

[fscotte]

How'd Loar do it.

Not a question.

[Larry Simonson]

I'm just saying that if either the plane of the top of a tapered HS or the back of tapered HS is chosen as the reference plane, and no compensation is made, then something has to bend or be ill fitted.

[Jim Hilburn]

What John is saying is that maybe other than long Schallers, there is room for some wiggle. I have a set of Grovers out and it looks like maybe 1 degree or so to me.
I simply feel that having everything parallel and the shaft contacting the bushing squarely is better than the one point contact you get with the taper. that makes the bushing want to square itself and lift out of the hole.
I'm talking about new mandolins. The only reason for tapering I see is either because Loars were that way or you think it looks cool or both.

[HoGo]

Perhaps all currently available bushings are loose enough fit for the tapered headstock. I was referring to old Schallers that were at least 1/2" long in the wood and very tight. Perhaps there is barely enough play in the bushing, but it would require everything else being perfect, which is impossible on wooden object like this. Ten or so years ago they started using shorter bushings that are not so problematic.

[Jim Hilburn]

I think most folks have given up on Schaller anyway.