Reamer for Grover Tuner Bushings

First time build here, and I'm loving it. I'm about to install a set of Grover A-style tuners that I bought through Stewmac. I bought their drilling jig as well, because I'm sure there are going to be more mandolin projects in the future.

I've drilled all eight holes, no problem. The instructions with the drill jig describes the use of a stepped reamer for installing the bushings on the top side. However, Stewmac's instructions for the Grover tuners say to simply use a standard tapered reamer (which I have) to enlarge the holes for the bushings. My concern: with the shallow taper of the reamer and the required hole diameter for the bushing, that's going to also enlarge the entire hole going up to the tuner plate. It will be hidden, of course, but I'm surprised that Stewmac didn't use the opportunity to recommend one of their stepped reamers.

Any suggestions whether to carry on with the tapered reamer or stop and wait to get a stepped reamer first? I definitely want to do this by reaming. I've installed a katalox peghead overlay, and it would very likely splinter if I try to use a drill at this point.

Thanks

I'm assuming that's because they don't appear to sell a .324 reamer. I'd be tempted to test the tapered reamer on a piece of scrap. Make your mistakes there and not on the instrument.

Good point. I started with the reamer and then stopped when I realized it would be enlarging the entire hole by the time I got the bushing to fit. I'll try the scrap next. I guess they could have just advised to re-drill the entire hole to the larger diameter, which would give a similar result.

Well, physically I guess the post is bearing on the bushing on one end and is attached to the plate on the other. I don't know how much enlarging the hole at the base is going to affect things.

That's the same conclusion I reached. It's just taken me a while to get there after all the desired precision in drilling with the jig. I can count on the bushings being located properly when I'm finished, so it still served the intended purpose.

I have a file like counter sink that I use when drilling holes I don't want to split. I first use the counter sink to file a bevel on the hole larger than the drill bit I will be using (step drilling with successive bits means reaming each time). This allows me to start the drill below the surface of the top and avoid splitting. In circumstances where drilling is sensitive I use an old Millers Falls hand, non electric, drill and simply turn the chuck with my hand. It is very slow and very precise and you will feel when there is pressure before you chip or split your piece. It is not as slow as you would imagine and have drilled a lot of holes by simply turning the chuck.

Good idea. I have a ball shaped countersink that's made like a file that would probably work for that if I turn it by hand. That's another option to try. Thanks, guys.....back to the workshop!

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Originally Posted by Parker135

Good idea. I have a ball shaped countersink that's made like a file that would probably work for that if I turn it by hand. That's another option to try. Thanks, guys.....back to the workshop!

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I have a wooden handle on my counter sink, I turn the drill by hand with a drill bit in the drill, not the counter sink.

IMO, you are overthinking this simple job.
As someone suggested above all you need is hole big enough in the top of headstock to hold bushings safely in place in exact distances. What is underneath is completely irrelevant as the only bearing surfaces you want is the plate of tuners and the bushing. The SM steeped drill is just source of possible problems when the tuner posts bind against the small diameter hole in bottom of headstock when dirt or rust accumulates or changes in humidity changes the hole to slight oval etc. One single diameter hole (7 or 8 mm and reamed with tapered reamer if required) is all I've ever done and never had any problems.

I have found it amazing, for years, that Stewmac didn't sell reamers specific to the tuning machines they sell. Like for Grover 309's. Perhaps they've changed, but the last I knew they didn't. They can basically come up with an expensive device to hold a toothpick at a given angle (unnecessary) but can't offer a reamer specifically for the tuners that they sell.

https://www.stewmac.com/Luthier_Tool...g_Reamers.html

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Originally Posted by HoGo

IMO, you are overthinking this simple job.
As someone suggested above all you need is hole big enough in the top of headstock to hold bushings safely in place in exact distances. What is underneath is completely irrelevant as the only bearing surfaces you want is the plate of tuners and the bushing. The SM steeped drill is just source of possible problems when the tuner posts bind against the small diameter hole in bottom of headstock when dirt or rust accumulates or changes in humidity changes the hole to slight oval etc. One single diameter hole (7 or 8 mm and reamed with tapered reamer if required) is all I've ever done and never had any problems.

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Well, IMO, you're exactly right! I went ahead with the tapered reamer and the job is complete.

I did try the file-type countersink idea for getting through the overlay first, and then a drill held in the chuck from my Shopsmith. That made an easily controllable setup that I'm sure I'll use for something else in the future.

You can buy reamers in .001" increments from most industrial suppliers. But I find tapered reamers work great for tuner bushings. Do the first one, press it in with your thumb, then the dust on the reamer flutes marks where to put tape. With tape on the reamer, all your holes are the same depth, nice consistent results.

I am in agreement with Adrian and Marty. I too use only a tapered reamer after drilling the hole, and have not had any problems with getting tuners firmly seated. Using the tape to mark the depth the reamer goes in to is an important point for consistency.

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Originally Posted by Dale Ludewig

I have found it amazing, for years, that Stewmac didn't sell reamers specific to the tuning machines they sell. Like for Grover 309's. Perhaps they've changed, but the last I knew they didn't. They can basically come up with an expensive device to hold a toothpick at a given angle (unnecessary) but can't offer a reamer specifically for the tuners that they sell.

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I have asked them many times over the years to make reamers that fit the tuners they sell, especially the replacement bushings they supposedly make. They make a .328" bushing reamer that fits Waverly bushings. Their replacement bushings are .336". They told me Don MacRostie pushes the .336" bushings into the .328" holes with a press. No thanks. Don't need to split the wood. They would also be very hard to get out.

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Originally Posted by sliebers

They would also be very hard to get out.

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Sure they will start to offer their new "safety bushing puller" for mere $199!

I used to browse through their catalogs years ago nd lust for the cool devices but at the end being without too much money I started making instruments with just basic woodworker set of less than 10 tools (including axe, pocket knife, bowie knife, two chisels, one gouge, small handplane, saw...) and made my own tools, jigs etc as I needed them. It took me more time but it also honed my skills with these basic tools that are MOST IMPORTANT asset of builder.
The SM thingies are mostly for DIY or hobby guys that don't have the time to learn the traditional tools and want to go directly to jobs that they would otherwise botch badly. Most of the best makers or repairers use mostly basic handtools as they are the most versatile for wide variety of tasks.

The one time I needed to ream some tuner holes for bushings, I went to Harbor Freight and bought their supercheapo reamer. I am sure a really good reamer would be better if I were needing it often, but the HF reamer worked fine.

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Originally Posted by John Kelly

I am in agreement with Adrian and Marty. I too use only a tapered reamer after drilling the hole, and have not had any problems with getting tuners firmly seated. Using the tape to mark the depth the reamer goes in to is an important point for consistency.

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That's what I did as well, and I don't see any reason to do anything different at this point. HoGo has me pegged...I was overthinking it. I got it strung up today and got to play it a little. That's really fun, seeing and hearing it come alive for the first time. Now it's time to begin overthinking the finishing process.

Ditto for me. I happened to have a violin peg box reamer, it's a very gradual taper. I taper the hole until the bushing press fits to about a mm or so above the peghead, then tap it home with a little mallet and a dowel. No more bushings working loose! I wasn't smart enough to put tape on it !?! like I do with drill bits, I put a sharpie line at the level where the fit is perfect.