Tuner hole jig won't sit flush

[Phil O'Dendron]

While doing a refret on my old model A I noticed that the 'Relic' replacement tuners were not turning as smoothly as I thought they should. To verify that the holes were parallel and that the tuner posts weren't binding, I tried to check (using the jig) from the back of the peg head but saw that the end of the jig closest to the neck was lifted due to the curve down to the neck. The jig is obviously supposed to mount to the reverse side so that the tuner plate sits flush with the peg head and the holes are then perpendicular to the plate.
I have a mandolin build in the coming months so would like to sort this before I come across it again.

Any thoughts? Maybe a packer to bring the jig out parallel to the back of the peghead?

[sunburst]

I'm not sure I understand the question.
Is it what to do about this mandolin, or how to avoid this on a future mandolin, or... something else?

[Jim Hilburn]

Saw off the excess.(Of the jig, not the peghead)

[Richard500]

Analysis correct. Surgical treatment correct. The jig should not be longer than tuner plates for this reason. If you don’t care to bevel the end or chop it off, you will have to make, preferably, a four hole packing plate thick enough for all potential different heads.
The product is described as steel, but I’d bet not properly hardened, so it should saw or grind easily. It is probably too long in order to have clamp lands at both ends, so a bevel or step will preserve this function.

[John Bertotti]

Why not just use the jig from the front? On a new build just drill before the fret board is glued on from the front of the headstock. Unless you do a lot of work on existing instruments and need to drill from the back a lot. You did say new build right? Do you do a lot of repair work also?

[jim simpson]

The neck to headstock transition is what is not allowing jig to sit flat. I would tape on a wood spacer of even thickness to the bottom of jig and drill through it. The wood spacer should be flat against the headstock if it is made to the length of the headstock and not resting on the neck area like the jig in your photo.

[Richard500]

Why not just use the jig from the front? On a new build just drill before the fret board is glued on from the front of the headstock. Unless you do a lot of work on existing instruments and need to drill from the back a lot. You did say new build right? Do you do a lot of repair work also?

John, it’s because most headstocks are tapered in thickness, so if drilled perpendicular from the top, the plates will not fit flush.

[John Bertotti]

Ah, that makes sense! So either way using the stew mac jig you need to do a shim or mod the jig. But doesn't this mean the bushings won't sit flush?

[Phil O'Dendron]

Thanks everyone for your input. Yes, as Richard says, the tapering headstock thickness is why the jig is mounted to the reverse to ensure that the holes are perpendicular to the plate. I'd thought of making a packer but hadn't thought of just bevelling the underside of the jig end closest to the mandolin body (while still enabling a clamp to be applied). Thanks for that Richard.

[Jim Hilburn]

On the 5th page in this forum is a thread about tuner jigs and on the second page of that thread I posted a picture og my cut down version of that same S-M jig which I did to avoid the same problem. I must have taken the photo and then deleted it, but not doing it again.

[Steve Sorensen]

If you use the jig to mark holes in the top veneer, then use a well-squared drillpress with a bradpoint bit to drill the 1/4 inch pilot holes, with the headstock seated back-side-down on a waste board, the holes will be perpendicular to the back (and you will avoid this issue). This approach also allows you to more precisely set peg locations in the top of the peghead.

Steve

[HoGo]

There are several threads where everyone (including me) posted about their way of drilling headstocks and reasons why they do it that way.
There is inherent problem of tapered headstocks where the bushings need to be installed square to front side and tuner posts square to rear side. Because of teh taper the bushings won't be parallel to the posts. Most builders drill with the jig and then ream from front to assure the bushings will seat flush. Theere will be small angle of post through bushing but unless the hole in wood is very tight for the post no binding will occur (this can be often problem with "stepped" holes drilled by the S-M drill).
I personally drill from the front on drillpress (without jig, just mark the positions with an awl and use brad point drill). SInce the hole I drill is oversized I just need to ream front to accept bushings adn I'm good to go.
Here is the end of old thread about this.
https://www.mandolincafe.com/forum/t...hickness/page2

[Phil O'Dendron]

On the 5th page in this forum is a thread about tuner jigs..

Jim, I haven't found that thread on page 5 or 4, 6, 7. Any clues as to where I can find it?

[bennyb]

...Here it is Post 41

[John Bertotti]

My thread I forgot about. I just bookmarked it thanks for linking it!

[John Bertotti]

Hmmm, this is probably a very redundant question but Why are the headstocks tapered?

[sunburst]

Hmmm, this is probably a very redundant question but Why are the headstocks tapered?

Check out post #9 in the linked thread.

[John Bertotti]

Thanks! It took me a minute I went to the last linked thread and then realized you meant the one linked in post 12 above. Thanks again!