Building an odd mixture of solid and hollow body, any advice/warnings?

Discussion in 'Tele Home Depot' started by Johnny7s, Jun 14, 2018.

  1. Freeman Keller

    Freeman Keller Friend of Leo's

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    Cocobolo has two things going against it. First it is extremely oily and might pose problems when gluing it. You will see/read all sorts of suggestions how to deal with this - some people suggest wiping with solvent (naphtha or DA) right before gluing, some say that will only bring glue to the surface. Some people suggest using epoxy rather than HHG or AR.

    The second problem is that many people have an allergic reaction to cocobolo dust. I recently built a coco bodied acoustic (the head is my avatar) and I made it a point to ALWAYS be wearing a dust mask when I sanded it.

    As far as scale length, that is one of the very first things that should be determined when you start thinking about your build. Again, Hiscock covers that very nicely. Scale length does affect playability (and probably tone but that is far harder to define). Longer scale has higher tension for the same strings (it goes up as the square of length) so it is harder to bend and slightly harder to fret. Obviously the reach between frets is slightly longer - most people can compensate. You need to move things around on your layout - bridge and pickups. You'll also find that most Gibson f/b's have 12 inch radius to match ToM bridges, Fenders tend to be 9 or 10 or even less (and of course most Fender bridges are not fixed radius).

    People do adapt Fender bodies to take shorter scale necks - Warmoth makes conversion screw on necks (the don't meet the body at 16) as well as some long scale bari necks. Again, it is much easier if you define that at the very start of your design and then make the geometry work with the scale. (Btw, I always like to select my bridge at the start and actually buy it so I can include accurate measurements in the design of the guitar).
     
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  2. Johnny7s

    Johnny7s TDPRI Member

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    Thanks again, freeman...

    I had planned a Gibson scale from the beginning, but I have to admit one of the things you mentioned that I hadn't considered was the radius of a Fender bridge... I'll make sure the bridge I bought will work... Every guitar I've done so far has been 12" cause I also buy pre-slotted fretboards, till I can get a miter box and saw. I've done Fender scales, but all TOM or wrap around bridges.

    Hopefully his open D's and G's don't get more Dbs.... lol. That was a joke, but now I kinda bet that would matter if the posts don't adjust...

    (Have I mentioned I hope this becomes my job at some point.... I'll just change my name... )
     
    Last edited: Oct 23, 2018
  3. Johnny7s

    Johnny7s TDPRI Member

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    @Freeman Keller … I hope that didn't seem rude, I couldn't think of any other way to word it, lol. I very much appreciate your help.
     
  4. Freeman Keller

    Freeman Keller Friend of Leo's

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    Not a problem. I just wanted to remind you that mixing designs can bring up problems (again, Hiscock covers this very well). Not only are typical Gibson bridges fixed at 12 inch radius, most of them like the fret plane about 5/8 above the top. Most Fender bridges are adjustable but they like the fret plane 1/2 or a hair lower. Obviously its easy to change a Fender style neck (take a chisel to the pocket or throw in a shim) - its much harder to fix a glued in neck if you get the geometry wrong.

    I make it a point to always have the bridge I intend to use in my hand before I start any of the layout work. Its kind of interesting - I'm building a tele-thing right now and using a Gotoh bridge which has a much thicker plate than the ones I've used before. It looks like I'm going to have to route the pocket a bit deeper to compensate.

    ps - I was goofing around one day with a tele body and a ToM bridge to see if it would work. The bridge is sitting on little blocks that emulate the thickness of the studs - this is as low as it would go. Won't work without some serious angling of the neck (straight edge is sitting on the frets)

    [​IMG]
     
  5. Johnny7s

    Johnny7s TDPRI Member

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    Actually, of all things to overlook, that I hadn't even thought of... lol. In the past I've used a Stewmac radius block (a little wooden one, not even the beam... "abracadabra… stay straight.... lightly now... good vibes, good vibes....") to make sure that another fretboard radius ended up 12 inches... but like I said, I've always done TOMs or wraparound bridges.

    @Freeman Keller -The Hiscock book, I assume the "electric guitar" version? Kinda close to my deadline. Why don't you just write down everything you've learned along the way instead, I'll just print it out. :D

    Well... I looked at the top down measurements of the bridge I was going to use at Stewmac to plan my taper…. apparently, that wasn't the only angle I should have considered... ba dum dum…:p Plus they could have a mix up and incorrect specs...
     
  6. Freeman Keller

    Freeman Keller Friend of Leo's

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    Actually I can do that pretty simply. First, I know my target playing action for almost every instrument I build before I start. For most acoustic and electric guitars I like minimum fretboard relief (0.002 to 0.005), first fret action of 12 to 18 thousands, and 12 fret action of 60 to 90 thousands (classicals and resonators are different). My fretboard and bridge radius will always be the same (I don't do compound radius f/b's) so it doesn't matter what it is (I build guitars from 10 inch to dead flat).

    I also mostly use medium fretwire with crowns around 35 or 40 thou, but again, it doesn't matter since my reference is the top of the frets (the fret plane). I also assume that my fretwork will be perfect (and it is).

    Start with the fret plane hitting the top of the saddles at their absolute lowest position - you will never want your "action" lower than that, right (the strings are laying on top of the frets). Most bridges have somewhat more than 1/4 inch of adjustment (find out how much yours has). Raise the strings at the nut - that will raise them half as much at the 12th fret. Allow your relief - the will add about half at the 12th fret. Add any rotation you expect in the neck block and upper bout (significant in an acoustic, probably not so in an electric unless its a Fender with loose screws). By now you probably have 10 or 15 thousands of action at the 12th fret.

    Now start raising the saddles. For every X you want the action to go up, the saddle must go up 2X. If I want to go from 10 thou to 70 thou at 12 I must raise the saddle on that string 120 thousands - about 1/8 inch. Do your saddles have that much adjustment? If not you need to start with the fret plane higher or lower or whatever to get within range.

    You can do that as a side view drawing of your neck and bridge - a section thru any string (some of the string will have higher action, it is good to check each one of them). Once you have that drawing you can mark the bottom of the bridge - that will determine where the top is at the scale length. You can now draw the top and determine how much neck angle and/or overstand you need.

    Then when you build the guitar do exactly what you did when you made the drawing - adjust the neck angle, overstand and any arching of the top so the fretplane falls exactly where you want it at the bridge location.

    It doesn't matter whether it is a flat topped guitar with a screw on neck with no angle like a telecaster-clone

    [​IMG]

    A set neck semi hollow body with a flat top and angled neck like an ES-335-clone (the wooden blocks are the thickness of the studs)

    [​IMG]

    An archtop with a dovetail neck joint with both angle and overstand and a floating bridge (the board is not fretted so there are some business cards representing the height of the frets)

    [​IMG]

    Or an ordinary old acoustic with an angled neck, domed top and bone saddle

    [​IMG]

    The bridges on all of those are different heights but they are all treated the same.
     
  7. Freeman Keller

    Freeman Keller Friend of Leo's

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    The "top down measurement" will give you the string spacing at the bridge (which may be important to you as a player - I like slightly wider spacing since I am a finger style player). Once you establish the spacing at the bridge and nut you can add whatever offset you feel you need (most of the time its from 0.100 to 0.125 but again, it depends on playing techniques). That gives you the width of the f/b at the nut and bridge. That lets you calculate the width at the 12th fret and the body joint (12, 14, 16, 18 - where every you decide you want it). Then you can design how your body interfaces with the neck.

    Once you have the width of the f/b established you and use the top down measurement to make sure it is centered (or more correctly, that the bridge is centered once you have mated the neck to the body.

    [​IMG]

    [​IMG]
     
  8. Freeman Keller

    Freeman Keller Friend of Leo's

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    The last part of the geometry puzzle is where to locate the break points of the saddles relative to the scale length. Most electric bridge are pretty simple since they are adjustable (archtop bridges are simple since you just move them around until they sound right). The only issue is getting them located within their adjustment range. The StewMac fret calculator will help locate the bridge that they sell, but again, my rules of thumb are

    - most of the time I want about 1/16 compensation for the 1st string and 2 or 3/16 for the 6th, and

    - I know I will never want less than the scale length so if I put the minimum compensation at the scale I should be OK.

    There, start printing....
     
  9. Johnny7s

    Johnny7s TDPRI Member

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    Thanks yet again, @Freeman Keller! Done deal. (Well, screenshots taken...). By the end of this thread you'll have your own book prewritten ready for publication, haha!

    I almost didn't start this thread... I wonder if Rudolf would have found my Dads present this year in the scrap bin on the island of misfit toys.... lol.
     
  10. Johnny7s

    Johnny7s TDPRI Member

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    @Freeman Keller

    FYI, this is still in the works. I've had it strung up, but still need to route for a tele bridge. A friend sold me a used Duncan humbucking tele pup that coil splits, so I'll have a couple starting points covered as far as tone.

    here's the last test I did with dye, some brown and amber ColorTone in water. That was intended to be a carve top, and there should be enough left to mess up a few times if it gets scratched while routing.

    It looks a bit better with some maple scraped clean around the ports and outer edge.

    I shouldn't be getting so ahead of myself, but the first time seeing that wood wet with dye is one of my favorite parts. FinishDads.jpg
     
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