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Thread: Stromberg Voisinet tuners explained

  1. #1
    Registered User Denis Kearns's Avatar
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    Default Stromberg Voisinet tuners explained

    I now have three different Stromberg Voisinet mandolins, none of which have a complete set of functioning tuners. The nicer two have mahogany sides and back (laminate?) while the other appears to be made of birch. All three look to have spruce tops.
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    Patented in 1921, the Stromberg Voisinet tuners are difficult to dismantle without breaking them but are an interesting design. Tuner components are made of brass, steel, black “bakelite” and pot metal. They would have been much better and durable if the housing had been made of stronger metal (brass or steel). The bakelite (or whatever this black stuff is) is brittle at 100 years old.
    What follows are photos and my explanation of the tuner design.
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    Photo one shows intact tuners, next is extracted tuner, third is expanded tuner showing retaining clip used to secure worm gear shaft with tuner button. In this photo, the gear housing is missing the upper collar which helps secure the upper part of the “string” shaft.
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    Tuner components include Black bakelite disks & tuner buttons, Brass ring gear “string” shafts and washer/bearings, Pot metal gear housings (2 piece) and Steel worm gear/button shafts & retainer clips. Second photo shows gear shafts and retainer clip. Third photo shows pot metal housing with gear shaft and brass washer/bearing. Housing collar surrounding upper gear shaft broken at base where it connects to pot metal housing. This is not a bushing in the center of the bakelite disks (as some folks suggested) but gets broken off from the gear housing when the tuners are dismantled.
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    These gears are ambidextrous, constructed so that they could be used on either side of the headstock. I’m guessing that the black bakelite disks were pressed onto the gear housing and served to hold the gear tight in its individual headstock hole.

    I’m wondering if someone could 3D print copies of the gear housing in tougher material, as well as making replacement disks. The housing seems to be the weakest part of the design.

    I have not tried to dismantle any of the intact tuners but have enough spare parts to return the two nicer mandolins to playable conditions. The trick seems to be in removing the black disks without breaking the gear housing. Heat maybe? I’m not aware of anyone successfully dismantling and repairing these tuners.

    I have a few other ideas of better securing the gears to the headstock, but that supposes I can get a full functioning set.

    See also this recent thread:
    https://www.mandolincafe.com/forum/t...d-mando-tuners

    Enjoy!

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  3. #2

    Default Re: Stromberg Voisinet tuners explained

    Pot metal is a fairly non-robust substance and is prone to crack and crumble so that is probably the main cause of the woes inherent in these tuners. They appear to be too complex as well in comparison to rival types and my main experience is that the tuning is far too hard to fine tune with precision. Great exposition of the workings of these mystery objects of yore.

  4. #3
    Registered User TheMandoKit's Avatar
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    Default Re: Stromberg Voisinet tuners explained

    Thanks for the detailed and interesting explanation of these odd devices.

    I know very little about 3-D printing, but it seems like that might offer the best way to make a replacement for the broken parts, if it could be done from a sufficiently robust material.

    Like many creations of the late 19th/early 20th century, a very complicated solution to a simple problem. Although I'm sure someone will be saying the same thing about smartphones in 2125.
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    Moderator MikeEdgerton's Avatar
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    Default Re: Stromberg Voisinet tuners explained

    It's going to be shame to see some fine old instruments become unplayable. The plastic (for lack of another term) black disk could be easily printed on a 3D printer. It's a shame that some modern tuner could not be placed in that hole with a cover so that it functioned and could be repaired but still looked period correct. Barring someone with some pretty mad skills and equipment these might become a real white elephant.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

  6. #5

    Default Re: Stromberg Voisinet tuners explained

    Places that do commercial 3-D printing can make sintereable metal parts, but I haven’t looked at this area in years so don’t know what the costs are. Certainly the casting can be measured and programmed without too much fuss. The Bakelite ferrules can be very easily made on a hobby lathe out of any handy material, perhaps a black Micarta, and designed with a ridge or two so that it can be glued in place instead of pressed (less headstock splitting). To remove the old ferrules, again with minimal damage, I’d drill or mill them into fragments rather than pull them out, which, as said, will snap the casting end.
    A recent thread here concerns these tuners. My opinion was that the motivation was to allow the pressed design on the back of the headstock.

  7. #6
    Registered User Denis Kearns's Avatar
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    Default Re: Stromberg Voisinet tuners explained

    A friend suggested I talk to one of the folks at the local community college. Apparently they just got a new 3D printer. This may be a nice project for a student. Will have to schedule a trip up to the campus.

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    Default Re: Stromberg Voisinet tuners explained

    those cast pot metal pieces look evil. I have seen other contraptions that combine cast pot metal with steel moving parts - friction was terrible and wearing out of pot metal was insane. I doubt a 3D printed replacement would be an improvement wrt friction and cracking/fracturing (long term). Maybe 3D printed teflon-type self-lubricating plastic. But it will deform under string tension.

  9. #8

    Default Re: Stromberg Voisinet tuners explained

    I bought the S-V that Elderly had a few weeks ago, partly to enjoy restoring, and partly to investigate the tuners. Slightly miffed that they all worked! However, after the second stringing (the usual fretboard and bridge needed attention, and a prior sloppy fitting of the back had to be rectified with a binding rebate), one tuner started to slip. I had made replacement black ferrules already, in nylon, but now have to make a new tuner. It looks as if failure of the ferrule will also ruin the casting. Lots of really lousy design. Going with brass for several reasons, and not making it ambidextrous or dependent on the ferrule for strength. Also it appears that this part is thermoplastic, so not Bakelite. Will try to reuse both the worm and gear, as the latter is fairly hard to reproduce.
    Not intending production, but any interested S-V owners may pm me with their observations - maybe there’s a little market.

  10. #9
    Moderator MikeEdgerton's Avatar
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    Default Re: Stromberg Voisinet tuners explained

    If you could use a standard tuner, slightly modified with a custom printed plastic cover that made it look right you could be a hero to generations of people that will have these hanging on the wall because they can't be played. These are actually Uke tuners. I don't know about the post length but if there was some way it would be an answer.

    https://www.allparts.com/products/tk...d-ukulele-keys
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

  11. #10

    Default Re: Stromberg Voisinet tuners explained

    Certainly an option if the largest dimension is less than the hole in the headstock- close to 0.700” but the originals use a very small gear diameter on the post (0.300, another design error - simply too small for the torque), so if the new works fit, you’d be off-center with the post, which of course doesn’t really matter, and the worm shaft and button have to be worked decently close to original, also not a function issue. I may look into that if I give up on using original parts, which is a sort of neurosis with me, although I had no qualms about stripping the drab brown paint from the instrument and modding that.
    Since the worm shaft is what holds it all against rotation, no screws or fasteners would be needed; just a cut-down cheap piece of either a plate or individual tuner. Still need something on top for trim and also to hold down the mechanism with aforesaid off-center hole. It’s not only decorative. I’ll post pictures.
    I will give the brass version a try, since it’s minimal machining, lathe turned plus two bores and a saw slot - but the bores have to account for the wear in the gear and therefore require fussing as there’s no way to adjust it.

  12. #11
    Moderator MikeEdgerton's Avatar
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    Default Re: Stromberg Voisinet tuners explained

    I'm actually wondering about trimming the plates and it doesn't have to be that tuner. From what I'm seeing people generally have at least one tuner that is broken. I get keeping it original but the eventuality is that many of these mandolins won't be played because you can't fix the tuners. Just a thought. If you can modify a easily obtained part it might be better than reinventing the wheel.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

  13. #12

    Default Re: Stromberg Voisinet tuners explained

    Will try that too, but have to purchase that junk drawer; that’s better since it would be an easier recipe using presently available bits. Uke tuners are nice as the buttons are small. Made some “on screen” measurements yesterday, also of the enclosed variety, so will get both. Either case, the buttons have to be removable, so screw-on easier. Post lengths adequate in all cases, although for looks, will need trimming.

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    Default Re: Stromberg Voisinet tuners explained

    I have modified the plates on tuner to make them work several times. I don't have equipment to make metal parts, unless it's with the drill press and a file. Which I have done, but it is time consuming.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

  15. #14
    Registered User Denis Kearns's Avatar
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    Default Re: Stromberg Voisinet tuners explained

    I rummaged through my loose parts, including separate tuners and some old mandolin units, but nothing was small enough or had the proper orientation to fit both the hole for the casting and the hole for the tuner shaft. That even if I had cut the mandolin array into separate tuners.

    Looking forward to seeing what you come up with Richard.

  16. #15

    Default Re: Stromberg Voisinet tuners explained

    Click image for larger version. 

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    Not sure how to do an invisible repair without having access to good-working vintage parts.

    I did notice the guitar version of this body style uses a partially routed (not all the way through) slothead style which doesn't look too bad and may be a way to solve the problem and still give a somewhat period look and retain the engraved peghead backside and should allow the use of more common tuners or vintage 4-on-a-plate tuners. Just a thought...

    Another thought was, these sure must sound good for people to go through all this trouble.....?

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    Default Re: Stromberg Voisinet tuners explained

    i am so happy to read these messages. it is right up my alley, kludge it and fudge it until it works. but I am curious whether the obvious path works or not, plug all these funny cutouts in the head stock, drill new holes and install standard tuning machines. a future-proof solution. it seems to me that the original machines, with their small diameter cogs, will never work well to modern expectations. but maybe I am wrong and a happy owner can report that after cleaning and lubing these machines work as well as the modern ones. main thing is to keep these mandolins in play for the next 100 years.

  19. #17

    Default Re: Stromberg Voisinet tuners explained

    Glad there’s interest. So far, couple of experiments, shown in the photo. However, a friend had a better idea that I may get to fairly soon. In the photo, the MK I aluminum machined housing for the original parts is shown, not yet cut off the bar stock. This uses the mangy, worn spur gear, but supports everything better. It fills the headstock pocket to the top and doesn’t rely on the black ferrule for anything. Next to this is a standard single enclosed uke tuner intact and cut down to fit the headstock recess with no modification. It would be stronger, but requires two or so additional parts. The next version, MK III will have new, strong gear and post, adapted to an aluminum housing (at first). Next week, maybe. It would also require no changes to the headstock, but the peg axis will be off center with respect to the hole.
    Click image for larger version. 

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  21. #18
    Registered User Denis Kearns's Avatar
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    Default Re: Stromberg Voisinet tuners explained

    Way cool, Richard. I’m looking forward to seeing the MK III model!

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