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Cutting into kerfing for battery box - OK or bad idea?

Discussion in 'Tele Home Depot' started by telel6s, Mar 3, 2021.

  1. telel6s

    telel6s Tele-Afflicted

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    Looking for some advice.

    I'm planning to add a piezo and preamp to a hollow thinbody resonator guitar (Dean Cutaway)* to use along with an existing lipstick pickup.

    The problem is that the battery box requires a one inch wide hole but the width between the kerfing ranges between 0.78 inches near the end block (preferred place to put the box both esthetically and because that's the area of the jack and pots) up to 0.98" at its widest along the waist. (Yes, the guitar is a half centimeter deeper in the middle of the body versus at the end or neck joint, something I hadn't noticed until taking a caliper to it.)

    So in either case I would need to cut away some of the kerfing along a length of 1.375 inches. Down by the end block it would mean removing just over a tenth of an inch from each side.

    This seems like such a small amount that it won't cause any problems. Due to the design of the guitar all work would be done from the outside using a Dremel, small hand saw and sandpaper.

    Top, back & sides are all laminated mahogany. There is no traditional internal bracing since the top has the big ring for the resonator cone and the back is arched.

    But just to be safe I'd thought I'd ask here before cutting into things (or buying the parts for that matter). Thanks in advance!

    20210302_152529_HDR.jpg 20210303_095713.jpg 20210303_095613.jpg 20210303_111728.jpg

    * FYI - I got the guitar for under $100 since it needed the pots & jack fixed as well as a setup both of which require removing the resonator assembly so I figured, "What the heck, let's throw a piezo on the bridge, too, while everything is opened up." I need a preamp on the piezo so I can blend it with the magetic lipstick pickup.
     
    Last edited: Mar 3, 2021
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  2. bender66

    bender66 Poster Extraordinaire

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    I'm curious as to the kerfing discussion. I've spoken to my friend who's built many a guitar regarding it.

    I have a big 295 type body/neck here sans kerfing.
     
  3. yepyep

    yepyep TDPRI Member

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    You'll be fine in my opinion. Such a small amount in what I assume is a very rigid build won't shake things up.
     
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  4. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    Since the guitar is bound it shouldn't hurt a bit. Personally I hate any kind of pickup system that requires cutting a hole in the side of a guitar - that is irreverseable if you ever decide you don't like it.
     
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  5. telel6s

    telel6s Tele-Afflicted

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    Interesting about your 295-type. I'm no expert or builder but have always assumed that all full hollow guitars had kerfing to give support and gluing surface to the top and back.

    But you did make me check my 1967 Yamaha SA-15 which is a thin hollow body (1.75" vs this Dean's 2.5"). No kerfing! But the Yamaha has arched maple top and back. It also has a decent size block for the bolt on neck. And while I think the rest of the body is hollow, it's possible there is another block under the bridge - the f-hole is too small to see in that far and in the roughly 25 years I've owned it I've never taken off the pickguard which would expose the hole for the control knobs.
     
  6. telel6s

    telel6s Tele-Afflicted

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    In general I agree with you. But this guitar came from the factory with holes for the lipstick pickup's volume, tone and output jack already drilled in the top and side. So adding one or two more is no big deal to me (it will get a 3rd control pot, too). I already know that the lipstick pickup on its own just sounds like an electric guitar with really no hint of the resonator. The f-holes are too small to slip a battery through. And at the price I got this guitar, if I make it more playable than it was I'll likely increase its value by, oh, $20 at least;).

    The other option would be to cut a hole in the back for the battery box. That would be easier to do but somehow seems like a worse option long term.

    Because this is a thinbody resonator, none if these things will have an effect on the acoustic sound.
     
  7. BigTwangTheory

    BigTwangTheory TDPRI Member

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    I bet you could go on ebay and find a different battery box that would simplify the installation. But I also bet you'll be just fine with your plan. I would go for the spot where the least kerfing need be removed
    Normally I discourage customers from putting anymore than the bare minimum of electronics (Pickups jack volume) in an acoustic. Electronics are better put in a pedal on the floor. But this is really an electric guitar. That happens to kind of do an acoustic thing as well. I bet it will be a fun and useful thing when you are done.
     
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  8. Boreas

    Boreas Friend of Leo's Silver Supporter

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    I have seen many guitars where the kerfing is partially cut away to allow for a top or back brace to continue on to the side. I can't imagine removing a small portion would cause any problems. But a guitar, cut once, is no longer the same guitar. In this case, I wouldn't worry. It isn't a '35 Martin after all. Looks like an interesting project.
     
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  9. telel6s

    telel6s Tele-Afflicted

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    Thanks all.

    I've looked at measurements of several battery boxes. They are all about the same size because 9-volt batteries are all the same size.

    I've added preamps and jacks and battery boxes to inexpensive acoustic guitars before. I get the "don't defile the instrument :eek:" attitude but in many cases you're not doing anything the factory doesn't do on basically the upgrade of the same model. Done right it's no different than routing out a Tele for a neck humbucker.

    As Boreas said, this isn't a 1935 Martin. It's a $399 Dean that was already in need of repair work. If I damage the guitar it won't be because adding the piezo, preamp, battery and extra volume control was a bad idea; it will be because I screwed up at some point along the way where a more skilled person would get it done right.

    All that said, I'm now thinking I'll put the battery where the jack currently sits at a slightly wider point in the body and then see if I can use an endpin jack. That still requires reaming out the hole for the jack and I need to check if the trapeze tailpiece works with that. One of the preamp I've installed came with a battery box/output jack combo but it orients the battery in the other direction and is therefore too wide.
     
    Last edited: Mar 4, 2021
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  10. bender66

    bender66 Poster Extraordinaire

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    Mine is a "sample" kit of asian descent got for a good price. I was wondering if I should add kerfing. A good luthier friend said some hollows dont have it.
     
  11. Boreas

    Boreas Friend of Leo's Silver Supporter

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    We will need pix of the final product.
     
  12. telel6s

    telel6s Tele-Afflicted

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    We'll that goes without saying. Audio clips, too, because that's the important part.

    Endpin jack won't work because of the wood ring for the resonator will block it. Ordering parts this weekend. Due to other stuff to do in life, this could be three or more weeks until it's finished.
     
  13. Boreas

    Boreas Friend of Leo's Silver Supporter

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    How did you like the guitar prior to changing it? It looks like an interesting instrument. I have been considering a National Steel copy. Can't decide on a wood or metal body. Will mostly be played acoustically.
     
  14. telel6s

    telel6s Tele-Afflicted

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    Liked it well enough to pay $90 for it. The resonator sounds like a resonator but the small body limits the low end and its acoustic use to sitting on a couch type of thing. Worked for playing some folkie stuff around a Solo Stove last fall.

    But beyond that, the strings were old and way to thick for my liking. It comes with 13-58 acoustic strings which even in open Db or F# I found to be way too stiff for enjoyable playing. It needs a better set up. I'll be doing a new nut to raise the strings at that end, lowering the saddle, and tweaking the neck to get the strings at a more consistent height from end to end.

    Plugged in it sounded like a generic electric guitar. Not horrible but nothing special. I'm guessing that the dirty bronze wound strings had something to do with that. Also, due to the set up it was not very loud and I couldn't raise the pickup any more. New custom guage strings have been ordered from StringJoy: nickel wound 12-54 with a wound 3rd.

    So I definitely bought this as a project. A bit of reaction & stress relief from what was going on in the world (and cheaper & healthier than drinking too much bourbon :D). I'll be create a new thread showing all the changes, the finished guitar, and some demo sound/video once I'm done.
     
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  15. Boreas

    Boreas Friend of Leo's Silver Supporter

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    "Too much bourbon"? I don't understand...

    I cured my bourbon addiction with Irish whiskey.
     

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    Last edited: Mar 6, 2021
  16. Peegoo

    Peegoo Poster Extraordinaire

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    Another option that's easier is to make a little wood plate that's the same thickness as the kerfing, and glue it to the side between the kerfing. This will bring the mounting surface flush with the kerfing.
     
  17. telel6s

    telel6s Tele-Afflicted

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    Ha ha ha ha! Good point.

    I was just telling a friend earlier this week that I drank Jim Beam during college football games sitting along the train tracks just beyond the end zone. No bad memories, in fact lots of good memories. But it ruined my palette for appreciating good bourbon. So lately I have been experimenting with Irish and Scotch.
     
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  18. telel6s

    telel6s Tele-Afflicted

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    I get what you are saying, but because the plastic battery holder is wider than the space between the top and bottom kerfing, I'd still need to cut into the kerfing for the battery box hole.

    I'm going to position the battery farther down the edge, where the output jack currently sits and where the body is slightly deeper. I'll still need to cut into the kerfing but minimally so.

    Based on the conversation here and some other things I've read, I feel confident that all will be fine so long as I don't cut a big wedge out of the guitar with a jigsaw. (note : I will not be using a jigsaw)
     
  19. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    If you want some help setting it up let me know - I currently own three resonators, one which I built. There are a lot of quirks and tricks to setting them up, I can talk you thru a few things I know.

    IMG_2509.JPG

    I'll also say that I've never heard a pickup in or on a resonator that sounded like the guitar. An internal mic is about the best of the options, a SM57 pointed at the sound hole is what I use.
     
  20. telel6s

    telel6s Tele-Afflicted

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    Thanks. I might take you up on that if I run into problems. I've already fallen into some internet wormholes about the intricacies of resonator guitars. But it's interesting stuff and I tend to be methodical and read a lot before I eventually make all my mistakes.


    Well, this thinbody Dean is never going to sound like one of your beauties. It's more like one of those 6-string standard guitar tuned banjos that kind of sound like a banjo but even the uninitiated can tell something is not quite right. If the piezo can add just a little reso/acoustic flavor to this I'll be happy.
     
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