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Drilling volume pot hole

Discussion in 'Finely Finished' started by pforsell, May 13, 2012.

  1. pforsell

    pforsell TDPRI Member

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    Hi. This is the only forum where I get great, consistent answers. I'm about to drill a hole for my volume pot on my newly painted guitar. I was going to use blue painter's tape to protect the finish.

    My question is do I drill going from inside the cavity out, or from the front of the guitar into the cavity? Which way is safest for the finish? I have made holes bigger by going from the cavity out, but this is drilling an entire new hole. thanks in advance,
    Pete
     
  2. Bud Veazey

    Bud Veazey Tele-Holic

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    It would have been better to do your drilling before finishing, but since that horse it out of the barn you should put the masking tape on top of the body and drill from the top. The tape will help prevent finish shipping. Happily, the washer and knob will cover any small finish chips around the edge of the hole.
     
  3. pforsell

    pforsell TDPRI Member

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    Thanks

    Thanks for your input. Yeah, hole first would have been better. Any other advice before I get the drill out?
     
  4. tap4154

    tap4154 Doctor of Teleocity Ad Free Member

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    I think I'd use the pot's flat washer (ID) to draw an outline of the hole, then carefully score the finish just a bit larger with a sharp hobby knife (don't slip!). Also use a punch to mark the center and hold the bit. That might keep the finish from lifting up etc.

    Drill using 3 progressively larger bits as well, and from the front.

    I'm not an expert, it's just how I'd do it if I forgot to drill the hole before painting ;)
     
  5. rip_topaz

    rip_topaz Tele-Meister

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    If you can fit a block of wood into the cavity to give the drill something to continue into, it'll minimize chipping.
     
  6. Colt W. Knight

    Colt W. Knight Doctor of Teleocity Ad Free Member

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    Use a sharp FORSTNER bit.

    A lot of times, I finish the guitar before I drill holes, so I don't have to worry about them getting nasty or absorbing water during the buffing process. I simply lay down a nice piece of blue painters tape, center punch where I want to dril, and drill very slowly using a forstner bit.
     
  7. dsutton24

    dsutton24 Doctor of Teleocity Ad Free Member

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    If you don't have a set of Forstner bits, get one, it'll be the best drill bit investment you'll ever make. Home Depot has a decent set that goes on sale regularly for $20.00, and they're pretty decent.
     
  8. pforsell

    pforsell TDPRI Member

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    Awesome. Thanks for the bit advice. You start small and work up to larger bit size right? How many bits would you use if you work up?
     
  9. bubba105

    bubba105 Tele-Meister

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    No, use one forstner bit slightly larger than the size of the shaft. A forstner bit has a point in the center which hits first. Next it cuts the circumference of the circle and begins hogging out the material inside the circle. As mentioned above center punch where you want your hole to be & go slow, let the bit do the cutting. Also mentioned above, if you can, get a backer board where the bit will exit, which gives you a perfectly clean exit cut. If not, go very slowly, let the bit cut the circle as it exits. If you push hard it will tear out, risking the flat surface your pot sits on. Take a practice run or two on some scrap.

    Good luck

    Richie
     
  10. bubba105

    bubba105 Tele-Meister

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    Oh, also, if your bit is the same size as the shaft & the shaft won't fit thru the hole, cut the hole. Next, get a dowel smaller than the hole, wrap some light (220) grit sandpaper around it. Enlarge the hole until the shaft fits, using DOWNWARD strokes, from the outside (finished side), working your way around the hole. Again, take your time. If you cut on the upward stroke the paper could grab the finish & lift it up. On the downward stroke the wood acts as a backer. This whole show only takes a couple of minutes but you really need to be in the zone. Make it take longer than it should.

    Richie
     
  11. SixShooter

    SixShooter Friend of Leo's

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    I advise against working.your way up in size. Do just as others have suggested. Use awl to mark the hole and then drill with a forstner bit. If you were to drill a smaller hole first you would not be able to center the forstner bit.
     
  12. tap4154

    tap4154 Doctor of Teleocity Ad Free Member

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  13. pforsell

    pforsell TDPRI Member

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    When you use the awl to mark the hole, just a little tap? Sorry, never used one before
     
  14. SixShooter

    SixShooter Friend of Leo's

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    Right, just a tap to make a small mark or dimple in the wood. Then you can set the point of your forstner bit in that hole.
     
  15. jefrs

    jefrs Doctor of Teleocity

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    Unlike a centre punch used for metal, a proper carpentry awl (bradawl) has a screwdriver type handle, you push and twist it into the wood. Straight edge blade for screws, spear-point or needle point for drilling. You can use an old dart head.
     
  16. Gnobuddy

    Gnobuddy Friend of Leo's

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    One more vote for using a Forstner bit. Any time I want a clean hole in wood this is what I use. Even a spade bit would be better than a regular twist drill bit for your situation, but a Forstner bit is better yet. The sharp cutters will make a clean cut through the finish, as long as the finish was properly applied to the wood.

    Harbor freight carries a decent set of Forstner bits at an affordable price: http://www.harborfreight.com/16-piece-titanium-nitride-coated-forstner-bit-set-39812.html

    -Gnobuddy
     
  17. tap4154

    tap4154 Doctor of Teleocity Ad Free Member

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    I'd stay away from the spade bits. Those things just tear wood up and shatter it underneath.
     
  18. pforsell

    pforsell TDPRI Member

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    Picked up the forstner bits. Thanks for the advice. I also bought a regular awl at the store. It has a pretty sharp point. If I'm drilling from the top of the guitar finish, just a dimple in the finish right? I'm nervous the awl might do damage to the finish. I may dive in soon so let me know! Thanks again for the ideas.
     
  19. Stuco

    Stuco Poster Extraordinaire

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    I'm not a woodworker by any means but I've had luck by getting the hole started by drilling backwards. This gets you started without risk of tearing. This could be terrible advice so take it at face value but it works for me without having the best possible bits
     
  20. Gnobuddy

    Gnobuddy Friend of Leo's

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    I've never had a problem with them as long as I:

    (a) Back the item I'm drilling with a piece of scrap wood and let the bit cut into the scrap as it finishes going through the workpiece.

    (b) Keep the rpms low.

    (c) Feed the bit with light pressure and let it cut its way through the wood, no forcing.

    The larger diameter spade bits have two sharp "teeth" at the outer corners, and these cut into the material before the main bulk of the wood is removed. So the bits tend to make a clean cut at the periphery of the hole (which is where the guitar's finish is), even if the wood removal inside that periphery is a little sloppy.

    I'm not a luthier, but I used to build model airplanes and that involved some delicate woodworking from time to time. I have hole saws, spade bits, and Forstner bits, and depending on the particular circumstance, any one of those three might be the best choice.

    One nice use of the Forstner bits was cutting clean, shallow holes in which to insert and glue small rare-earth magnets. The magnets are so strong that this is a convenient way to attach removable battery hatches and so on to the model. It just snaps on and stays there due to the magnetic force.

    -Gnobuddy
     
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