# Instruments and Equipment > Builders and Repair >  Convert Grover 309N Tuners to Worm Under?

## Parker135

I'm finishing mandolins 2 and 3 in my budding building hobby, based on the Gibson Army/Navy style from Crystal Forest plans.  I decided to strike out boldly and experiment with a snakehead version on one of them.  I downloaded pictures of Gibson snakeheads and laid out something close to the original series, including tuner placement.  Now that I'm about ready for final polishing and installing hardware, it hit me that the tuners on this one are going to work in reverse to normal.  Duh.  Is it possible to disassemble the Grovers and reassemble as worm-under?  I did this once on an inexpensive banjo kit, but not with Grovers.  

Otherwise, I guess my options are to live with a non-traditional shaft location with worm-over, which doesn't look too bad, or go with reverse operation.  Stewmac makes a "golden age" tuner that would have solved this problem, but it has a narrower, traditional hole spacing and I've already drilled for the Grovers.

Any other suggestions?  Thanks.

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## Ray(T)

Not all snakeheads had worm under tuners.

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## Rob Roy

If your peghead is tall enough for them to fit worm-over, I'd install them that way. The physics of that orientation levers the cog gear into the worm. They work very reliably and smoothly set up that way. I've used them on several builds and they work as smoothly as other tuners costing twice as much.

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## MikeEdgerton

You can't just disassemble the Grovers and get them to work right. The worm gear is cut at the wrong angle (see the image below). I'm assuming you are looking for worm under A style tuners in the normal modern 23.0 mm (.906) post spacing, Is that what you are looking for?

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## MikeEdgerton

Rubner made an A style worm under set in the modern post spacing. I have no idea if they are still available and in what finishes. They are nice tuners but a bit sketchy when it comes to availability and they have some odd finishes (I'm a traditionalist).

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## Parker135

I'll try to answer everyone here in one go.  

I thought if I could get these apart that I could flip both the worm and ring gears between the two mounting brackets to get what I want.  However, I started trying to get them apart last night, and it seemed like they really did not want the screw in the end of the worm gear to come out.  Maybe they used some kind of thread lock on it.  It didn't seem like a good idea to push it and maybe mar the head of the screw.  And even then, I don't know if the bearing tabs on the brackets are the same on both ends of the worm.  I was hoping someone here had already been through this.

I understand the advantages of having the worm gear pulled into the ring gear with worm-over, and I do have enough real estate on the peghead to install them that way.  That's probably my best option.  Luckily I haven't drilled for screws yet.

I'm looking for modern spacing to match current Grover tuners, so that eliminates the original .906" tuners.  I will look for Rubner tuners, but I have a feeling they may be a little dear for this application.

Thank you all for your quick replies!

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## MikeEdgerton

> Not all snakeheads had worm under tuners.


Indeed, here are four on the first page of 1925 from the Mandolin Archive

http://www.mandolinarchive.com/gibson/serial/80434

http://www.mandolinarchive.com/gibson/serial/80515

http://www.mandolinarchive.com/gibson/serial/80618

http://www.mandolinarchive.com/gibson/serial/80631

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## Parker135

Nice.  Thanks for posting those.  I mispoke in my reply above.  The current spec is .906".  It appears Rubner has them in worm-under, but I'm going to go out to the workshop and look once more at how I drilled for these Grovers to be sure I have room for the worm-over installation.  If so, I'll press on with what I have.

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## Parker135

I have room on the peghead to install the tuners as worm-over, but they're going to look a bit funky since I located the holes assuming worm-under.  It puts the keys a bit too close to the end of the peghead.  It's obvious (now) that it would have been much better to locate the tuners properly for worm-over.  The plainer version of the Rubners isn't that much more than the Grovers, so I think I'll check with them while the finish is curing.

I guess having bass-akwards tuners is not the end of the world if it comes to that.  I'll have a nice little reminder to think ahead a little more every time I tune up.

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## MikeEdgerton

I try not to keep reminders around of my screwups. There wouldn't be room for anything else.

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## pops1

I replaced the tuners on my old Gibson long before there were anything available to fit the spacing. I cut the plates at the screw holes to make them fit . They fit the screws holes better if I flipped them, so they turn backwards. I have never minded and even after playing other mandolins for a decade or more now when I play the Gibson it just seems natural.

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## fatt-dad

likely too late for my advice. . .

I've had two worm-under snakeheads made for me. In both instances, I had the builders use the stew-mac restoration tuners (made as drop-in replacements for the teens Gibsons) and had the peg holes drilled to those spacings.  I love the look and I am just fine with these tuners.

Heck, the tuners on my 1920 A3 are still working just fine!

f-d

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## MikeEdgerton

Unless I'm looking totally wrong at these Gotoh's they appear to be worm under.

https://www.lmii.com/gotoh-mandolin-...d-buttons.html

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## Parker135

Yeah, that would have a been a good way to go.  Unfortunately I've already drilled eight perfectly spaced holes for the modern spacing.  I've contacted Rubner's about their worm-under offerings and they're not making any at present while working to get some new F-style tuner out.  He asked "  Have you thought about reversing a set of worm over?" so I'm wondering if he means to install them so they tune backwards of if he's suggesting maybe their standard tuners can be swapped to function as worm-under.  I'm pretty sure moving the worm and gear to the other opposite mounting bracket will make a functional worm-under, but only if the worm shaft can fit either direction.

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## MikeEdgerton

I doubt you'll find these but the Gotoh part number above is MA40R. They are worm under A style tuners in the same drilling as you have.

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## Parker135

Yes!  Those Gotoh's even say "reverse gearing." It certainly looks like the worm gears are leaning the correct direction.  Thank you Mike!!  I'll double check and then get an order off.  Thankfully, 23mm spacing as well.

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## Parker135

Ordered.  Five-seven business days.  You guys were a huge help.  Thank you!

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## CarlM

> I thought if I could get these apart that I could flip both the worm and ring gears between the two mounting brackets to get what I want.


Just to be clear.  The worms are cut either right or left handed.  Flipping them over does not change the spiral on the worm.  It is just like screw threads.  Turning them end for end does not make the turn the opposite way.

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## MikeEdgerton

> Yes!  Those Gotoh's even say "reverse gearing." It certainly looks like the worm gears are leaning the correct direction.  Thank you Mike!!  I'll double check and then get an order off.  Thankfully, 23mm spacing as well.


It was weird enough trying to find worm over F tuners, this was my first foray into finding worm under A tuners with modern spacing. I hope it works out well for you.

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## Parker135

> Just to be clear.  The worms are cut either right or left handed.  Flipping them over does not change the spiral on the worm.  It is just like screw threads.  Turning them end for end does not make the turn the opposite way.


Hi Carl,

I've been sitting here twisting a Grover tuner in all kinds of ways.  You're right.  I think my memory of doing this on an inexpensive banjo kit, or maybe a mountain dulcimer, involved  gears that could be flipped over when reversing the orientation of the worm gear.  That seems to get the desired result.

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## Parker135

> Unless I'm looking totally wrong at these Gotoh's they appear to be worm under.
> 
> https://www.lmii.com/gotoh-mandolin-...d-buttons.html


Just to close the loop, the Gotoh tuners from LMI are indeed worm under.  They arrived today.  Thanks, Mike!

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## MikeEdgerton

Very cool, post some pictures when you're done.

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