DIY Neck Tensioning Jig (Vinson/Gilbert)

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by galibier_un, Aug 21, 2019.

  1. KGWagner

    KGWagner Member

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    I don't have a pic of the base at the moment, but as you imagined it's very stable as is. But, if I had it to do over again, I'd probably build a cart w/ drawers and top, sorta like you describe yours. As I'm sure you're aware, tool storage for easy/rapid access and organization can be a real pain in the shorts, even if you have a lotta space.
     
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  2. Steve_U1S

    Steve_U1S Supporting Member

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    Whoops - very true... I had the support rods in my mind rather than the brass gauge support rods.
    ... and while that's true that they only have to arrive in the ballpark of the rather large adjustment range of the dial gauges, it would madden me to no end having to fight against impressions in the rod, especially if it's preventable - I also acknowledge that that's likely just me =]
     
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  3. Steve_U1S

    Steve_U1S Supporting Member

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    Absolutely - you can have unlimited space... but if those tools aren't essentially within arm's reach, they're less likely to be used.
    The right tool for the job, unless it's in the other room... in which case, "hold my beer" - LOL

    (Irony alert; I'm a non-drinker... for me it would more likely be "hold my tea..." but that doesn't sound near as 'cool' =])
     
  4. galibier_un

    galibier_un Supporting Member

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    I got fairly far along with the project, and now need to make a mess of sawdust with the Skill saw and router - to make the wood parts and the surrogate bodies for the bass and guitar scale necks along with a few layers to position everything at the right height.

    Approximate project cost is as follows:
    • Two dial indicators: $40.30 ($10.40 of this was shipping)
    • Aluminum beam: $20 (an estimate - I bought some other scrap and he didn't itemize)
    • Cheap top mount Tele bridge ($0.00) - from my parts bin, along with saddles I'll never use.
    • 4 string Affinity bass bridge: $9.95 (eBay special)
    • Miscl. hardware: $7.50?
    • Scrap wood: $0.00

    The journey started with a trip to my local aluminum scrap yard. Every city should have one of these. It's a veritable playground and this out building is only a small part of this huge yard:

    [​IMG]


    Here's the basic layout. The support struts are in holes for the 25.5" scale, as are the dial indicators.

    The headstock jack, nut "pull-down", and first fret support are shared by both scale lengths.

    The wide, top section of the beam is about 3/8" thick, so I could directly tap 1/4 - 20 holes in it.

    The wood for the surrogate bodies / bridges is in the background. I still need to develop a mount for these, as well as to cut several pieces of wood to get everything to the right height.

    For the time being, I have plastic caps on the support posts and the "jacking" post, but I'll eventually make wood caps for these.

    [​IMG]


    Here's a close-up showing the dial indicators. There are two sets of holes - 1 for a 25.5" scale and 1 for 34". The large "unused" holes for the 34" scale show how I'm providing clearance for the dial indicators.

    I made a mistake here. Note that on the unused set (the 34" scale holes) there are faint hole outlines (plugged holes) on a line from the center of the large holes and perpendicular to the length of the beam. This was my first attempt at locating the support posts for the dial indicators.

    I realized that I was cutting too fine a line and couldn't quite reach the neck center line with the indicator pin.

    I drilled extra holes at approximately a 45 degree angle. The eccentric mounting position allows for rotating the indicators in order to position the pin along the center line of the neck.

    The large hole allows for plenty of clearance for the gauge while positioning it.

    The simplest solution was to tap all of the holes and use two nuts jammed together to perform height adjustment. I still think this is a good idea for all of the posts except for the dial indicators.

    With this setup, I'm doing the same thing with the dial indicators, but this is primarily out of expediency since they need neither the same precision nor as solid a fixation.

    [​IMG]


    ... Thom
     
    Last edited: Sep 20, 2019
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  5. walterw

    walterw Gold Supporting Member

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    so the rods thread into the big bar itself? the two nuts jammed together serve as a grip to spin the rod and the third nut at the bottom locks it down once you get it where you want it?

    makes sense, you might as well make that third nut at the bottom a wing nut so you can hand-tighten it.

    what about the eye loop pull-down? that won't work by spinning it, it needs to be drawn down while remaining in one orientation.
     
  6. galibier_un

    galibier_un Supporting Member

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    Yes, the paired nuts jammed together are to spin the posts. A wing nut sounds like a good idea for the bottom nut.

    I confess to being a bit clueless about the eye loop pull down. I thought about the spin aspect and was looking for turnbuckles to get around this, but in my initial search, the ones I found were really long. I also searched for rod couplers with half the thread being left handed, but haven't come up with anything yet. It's definitely an unsolved problem.

    [edit] I hate the thought of this, but I just noticed that a left handed tap can be had for under $5.00.

    ... Thom
     
    Last edited: Sep 20, 2019
  7. walterw

    walterw Gold Supporting Member

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    you said that beam is a "C" extrusion? meaning the unseen bottom face of it is open?

    just drill a bigger hole for the pull-down to slip through the top of the beam and be tightened by a wing nut from underneath!

    it would mean the beam needs to be mounted up on something so that you could reach under there
     
  8. galibier_un

    galibier_un Supporting Member

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    Thanks!

    Yes, the "C" extrusion has an open bottom (3 sides of a rectangle).

    My work strategy is to stabilize the jig to my bench with some C-clamps, but I can likely tension everything up before clamping it into position.

    Its not as if this is a production an environment, where this might be a workflow challenge.

    ... Thom
     
  9. walterw

    walterw Gold Supporting Member

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    it would mean doing a bunch of your work over, but my first thought while writing my last post had been to flip the beam 90° and mount all those parts onto one of the narrow faces of the beam, leaving one side open to reach in and work a pull-down wing nut while still having the whole thing mounted down flat.
     
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  10. galibier_un

    galibier_un Supporting Member

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    That's an interestingting idea. It would also give me the full length of the beam to clamp to the bench.

    Usually when I get to a mini roadblock in a project I'll park it for a bit and wait for inspiration to strike during a morning shower.

    This might be the time to do just that :confused:

    ... Thom
     
  11. KGWagner

    KGWagner Member

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    Assuming the jig or channel is straight along that edge, that'll also tend to be more indicative of how level the surface is you're clamping it to because it'll be stiffer along that length, so you don't inadvertently end up with a bent jig.
     
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  12. galibier_un

    galibier_un Supporting Member

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    I'll shoot a profile photo of this extrusion. I don't think this bar would bend if you drove a tank over it :D

    ... Thom
     
  13. KGWagner

    KGWagner Member

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    LOL! Ok, I didn't know. Just having a thought.
     
  14. galibier_un

    galibier_un Supporting Member

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    I loving the suggestions. This 4' hunk probably weighs about 8 pounds :eek:

    ... Thom
     

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