Tyrolean machine fitting

Discussion in 'Setup & Repair [DB]' started by bigolbassguy, Apr 5, 2011.

  1. bigolbassguy


    Feb 13, 2010
    Billings, MT
    I've got a set of Rubner Tyrolean machines to install on an old Engelhardt. I need to redrill the upper holes to get them centered but I don't have a 1:25 reamer. The original holes are just a straight 5/8 bore.

    My question is whether or not the taper is important with Tyrolean machines, or if I can just drill with a straight bit. A cello reamer is about $165, and I just don't have that much use for one.
  2. keiranohara

    keiranohara Commercial User

    Nov 7, 2007
    Ossining, NY
    Luthier at AES Fine Instruments
    $75 at international violin co. and it will make your installation a lot easier. Good investment if this is something you'll do more then once. you could drill out the near side of the pegbox (in relation to the gear) to a larger diameter and the far side a smaller one to match the relative size of the tapered shaft. The closer the fit the better because the string tension will be trying to torque the gear off the plate if given too much slop.
  3. vejesse


    Apr 8, 2006
    Madison, Wi
    Double Bass Workshop
    If the holes in your peg box are really 5/8 (0.625") then that will be too much slop for the Rubner machines with the tapered metal spindles. I remember the Engelhardt straight diameter tuner spindles being closer to close to 9/16"

    I think the big end of those Rubner spindles is around 0.590". As they're tapered the size of the small end depends on the length of course but it needs a real close fit. You'll be way too big without a patch.

    I's say go through the trouble of patching the holes, then use the cello peg reamer. If you don't go too far with the reamer you can get the perfect running fit.
  4. bigolbassguy


    Feb 13, 2010
    Billings, MT
    $75 is acceptable - thanks for the link and the advice. I'd been told by the seller that they were interchangeable, but things just didn't look right. I went ahead and ordered the reamer from International.
  5. I am doing exactly the same work just now except the Engel is new, bought as distressed from a shipper w/ all fitting removed. I found an (almost) exact match with a $75 Rubner set from International Violin. I had to fill and redrill most of the screw holes as they were very close but not perfect. I also had to elongate one peg hole to get the plate centered.

    The pegs fit very well at all eight pressure points and I am going to string it up this way. I don't think taper matching is that important for the load each point may be subjected to. This is far from the friction-hold fit required by a Cello peg. We want freedom not friction and so don't need a taper, I think. The plate helps with the load (or does it all) for the machine side and the free side is carrying 20# or less because of the way the string winds away from it. I would rather not fill, drill, and ream if there is no problem.

    Only my opinion, your situation may be different.
  6. bigolbassguy


    Feb 13, 2010
    Billings, MT
    Too late :) They were just a little bit stiff, though. Beware those cheap little screws btw. After piloting with a 1/16" bit, I twisted the head off of one and had to drill it out for a replacement.

    VJ, you were right about them being 9/16". I bored out to 5/8 for the plugs. I ended up plugging all the holes and redrilling to fit the taper.

    In hindsight, I shouldn't have used the original holes at the bottom of the scroll as guides. If I had taken a closer look at my documentation (I photograph everything before I start work), I would have noticed that the original machines were slopped on. So the new tuners aren't quite straight either. [email protected]#$. I told the guy to bring it back to me some time in the future for a do-over, pro-bono... [email protected]#$%. After a new FB + dressing, CF rod, adj bridge, soundpost, seam repairs and machines on top of the $700 my customer paid for the bass, He's pretty well maxed out on his investment. On the bright side, it sounds very nice, IIMSSM :)
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