Installing bushings into small peghead tuner holes

[dchernack]

Hi all,

I have a cute little taterbug mandolin which I've been working on as a project. When It came to me the headstock had broken off, but I've since repaired it. The headstock had some truly terrible tuners on it; one side was original, the other side a replacement. Both sets had normal size posts, but the holes that had been drilled into the headstock when the mandolin was in production are really pretty small compared to average. The tuners that were on it did not have bushings, so with the tuners in their attached position, there was a rim of open space separating the posts from the wood of about 1mm; which, when strings were attached, caused the posts to pull towards the nut and dented the wood. I took the older tuners off when I reglued the headstock, and have not put them back on since. I ordered a set of standard pearloid-button tuners from Golden Gate. I checked to see if I could get away with putting them on as the other ones had been without bushings, but what I discovered was that not only were the holes too small, they were also inconsistently spaced apart from each other.

I've come to the conclusion that the only way to get these tuners on this mandolin and get them to work correctly is to get the bushings into the headstock. However, the holes are too small to get the bushings in there without altering the size of the holes first. Do any more experienced builders or luthiers have any tips for this kind of situation? I've put a lot of work into fixing this instrument, and I don't want to give up, however, I would like to avert having to use the older tuners and install the new ones.

Thanks!

[Nevin]

This was discussed about a week ago here: http://www.mandolincafe.com/forum/sh...urled-bushings

[Michael Lewis]

If the holes in the headstock are not properly aligned or spaced I find it best to ream and plug the holes with tapered plugs. I use a violin peg reamer to prepare the holes and a peg shaver to cut the plugs the same taper as the reamer. Once the plugs are glued and trimmed and totally dried out then you can drill the new holes to match the machines.

Older machines were made with sufficient "slop" that they were tolerant of some variation in the hole spacing, but many modern machines are less so, and require more precision in the spacing of the holes. It is helpful for establishing the centers of the holes by removing the string posts and crown gears from the plates and mount the plates to the back of the headstock, then mark the centers of the holes so you can drill them after you remove the plates. Reassemble the machines and install them in the new holes. It's a lot of work but it usually gets the job done the first time through.

[Frank Ford]

Considering all the work you've done so far, I suggest you install the tuners with no bushings to keep the look a bit more "trim." Drill the holes to fit regular dowels, glue 'em in and level them. Then sand and apply a nice veneer to the face of the peghead. That will clean up the look of the crack and any misalignment of dowel/hole spacing. Then, drill the holes spaced accurately and install the tuners sans bushings.

I for one, never expect to find mandolin tuners spaced to match old bowl-back instruments - those makers appeared to have their own standards.

[sunburst]

Not a bad idea at all, and I might suggest that said "nice veneer" be something hard and wear resistant. When we don't use a metal bushing in a tuner hole, the bearing surface supporting string pull on the tuner post in the veneer itself. The end grain surface of a hard wood (like rosewood and ebony) is a pretty good candidate for that job, when you think about it, whereas something like mahogany burl, despite it's attractiveness in the eyes of many, would not support the tuner posts as well without metal bushings.