Eastman/K&K Tailpiece Changeout

I recently acquired a 2016 Eastman 605, one of their models with a factory-installed K&K pickup. I don't care for Eastman tailpieces and have swapped out a half dozen for Allens, but none involved endpin jacks. I would like to remove the endpin to see what I will need to do, but I don't know what the unintended consequences of doing that could possibly be, e.g. will I need to fish the wiring back out again and reconnect it? I probably will never use the pickup, but I don't see any downside to leaving it in and operable. Thanks for any insights on this specific pickup.

The strap button part of the endpin unscrews by hand. This reveals the nut which attaches the endpin jack. There's a hole for a nail so you can stop the jack body turning while you unscrew/tighten the nut.

If you keep the mandolin vertical so the jack doesn't fall inside the body, you're all set. A piece of thread to hold it in place while you fit the new tailpiece might be a good idea!

Thank you, ProfChris. So, does the nut tighten down against the tailpiece, or does the tailpiece fit over it? (I'm assuming the former, or it wouldn't have to be loosened.) And would I be correct in guessing that enlarging the standard endpin hole in an aftermarket tailpiece is the only adaptation needed for the changeout?

Thank you again.

Yes there's a bolt that fits over the tailpiece, then comes the cap that has the slot around it for the strap.

I don't recall how thick the metal is on the Eastman tailpiece, gut the metal on the Allen is substantial and the jack in its present set up may not protrude enough through the tailpiece plate to engage the lock nut. In that event, you'll need to fish the whole jack out through the f-hole, back off the nut and washer that seat against the tailblock by the appropriate amount, and reinstall the jack. It can be a trial and error affair and may take a few tries to get it right. The sleeve of the jack that the plug goes into has a hole through it that you can attach a thin wire or fishing line to to pull it back through the hole in the tail block.

Enlarging the end pin hole in a cast tailpiece can be a hairy operation. It needs to opened up to 15/32" minimum. For a cast tailpiece, I like to screw it down to a big chunk of wood like a 4x4 and then clamp it solidly to the drill press table. A metal drill bit of this size is going to grab like a monster and things can get violent. If you have a utility reamer that's big enough, that could be another option.

If you have to fish it out, take a 1/4" plug and plug it into the jack. Secure the plug to a dowel and you can slide the jack to the ff hole, adjust the inside nut, and pull it back very easily.

Thank you, Berto Boy. I was thinking more in terms of a round tapered file for enlarging the hole. There's no way I'm going to do an operation like that on my drill press unless I'm wearing chain mail or unless it could be done with a stepped bit. Eyeballing the tail sections of Eastman and Allen tailpieces, they appear to be about the same thickness, so there's that positive at least.

Start by unscrewing the strap button part. Then you can offer up the new tailpiece to see if the hole is the right size, and also check it's thickness. Fingers crossed its close enough not to need Berto Boy's instructions!

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Originally Posted by ProfChris

Start by unscrewing the strap button part. Then you can offer up the new tailpiece to see if the hole is the right size, and also check it's thickness. Fingers crossed its close enough not to need Berto Boy's instructions!

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My digital caliper says the Eastman is .071" thick and an Allen is .080," a difference of .009" This is a bit of a sloppy reading with neither tailpiece dead flat against the side, but I'm thinking the tailpieces are close enough to not require the dreaded adjustment.

Are the endpin/jack holes on the original Eastman tailpiece and Allen tailpiece located the same distance down from the mandolin top? In other words if you put the Allen on your Eastman is the new tailpiece hole concentric with the existing jack hole in the mandolin's tailblock?

I've installed a bunch of pickups and jacks in a bunch of fiddles, mandolins, ukulele, mandola, octave mandolin, mandocello, banjos, several guitars. The "nail hole" in the side of a switchjack type TRS output jack is of very little help when attempting to tighten up the jack in the tailblock.

The Stew-Mac "Jack-the-gripper" has been worth every penny to me.

I have taken a 1/4" plug, trimmed off the connections and ground down the remaining screw threads to 1/4", flattened a side and drilled a 1/8" hole through it that I've run strong thin nylon cord through. I remove the outer strap button nut and washers, loosen the outer retaining nut with Jack-the-gripper, plug in my modified 1/4" plug, remove the outer nut and gently push the jack inside the instrument with the nylon cord running out the tailblock hole. Remove the Eastman tailpiece, check the fit of the Allen. Modify the Allen jack hole as needed with a stepless bit (basically a reamer). Install the new tailpiece with your nylon cord running out the jack hole. Use the cord to pull the jack back out.

You may find that the extra thickness of the cast Allen tailpiece will require more of the threaded part of the output jack to come through to ensure your instrument cable plug can fully seat in the jack. If there isn't at least one thread protruding when you screw the strap nut on it could be a problem. In this case you need to protect the f-hole area with blue painters tape and carefully fish the jack out, adjust the inner sleeve and nut on the jack, then feed it back through the f-hole. Now pull the cord to get the output jack back through the tailpiece. Aren't you glad you modified that 1/4" plug and tied a string to it?

Install the retainer nut finger tight. Pull out the modified 1/4" plug. Use Jack-the-gripper to snug down the retainer nut. Install the strap button nut. Restring with Curt Mangan phosphor bronze strings. Tune up and play!

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Originally Posted by Mandobart

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I've installed a bunch of pickups and jacks in a bunch of fiddles, mandolins, ukulele, mandola, octave mandolin, mandocello, banjos, several guitars. The "nail hole" in the side of a switchjack type TRS output jack is of very little help when attempting to tighten up the jack in the tailblock.
....

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Hmm. Well, on the few I've done, those long-ish jacks of about 1/2" or slightly less diameter have a hex nut on the inside, against the tailblock, and a corresponding pair on the outside, and that "nail hole" absolutely allowed me to tighten the outside hex nut against the outside of the guitar while preventing the threaded outer part of that endpin jack from rotating. When that's done, on the typical setup, the "strap button" part threads down over the smaller diameter part left exposed, and that covers the hex nut that fixes the jack in place. I only hand tighten that outer, button part, but will put a drop of blue Loc-tite on it. Haven't needed any other tools for that, but maybe I'm misunderstanding the jack type, as I've not done a mandolin!

p.s. (edit) the length of the jack that extends out and should be about flush with the strap-button cap piece is a bit critical, at least you don't want it too short, or the 1/4" plug may not go in far enough to get "locked" in by the tip contact bit, allowing the cable/cord to disconnect or even fall out with just a little tug.