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Crap - spade bit fail?

Discussion in 'Hardware, Setup & Repair [BG]' started by sublimate, Nov 22, 2018.

  1. I couldn't find a Forstner bit in 11/16 (I admit, I only looked at Home Despot, not the best hardware store in town) so I gave it a try with a spade bit.

    I went slow, but as soon as the spade started to dig, CRAAACK!

    Is drilling tuner holes with a spade bit a complete noob no-no? I particularly don't like this kind that has a threaded point - worried it might have caused extra stress.

    Or have others had success with spade bits and did I just get unlucky? The way it popped open with a loud bang and stayed open makes me think there may have been residual stresses that caused this. Perhaps would have had the same result with a forstner bit?
    Old Garage-Bander likes this.
  2. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician, and Contractor to Club Bass and Guitar - Toronto
    It's the tapered threaded part that did the damage - it goes in like a wedge. Very definitely not recommended for this kind of work. In fact I don't think I would recommend it for any boring job - certainly not in hardwood. And spade bits don't create a nice clean hole, nor an accurate one. They are good for making approximately-sized rough holes.

    I would put a clamp across the crack (with a shaped caul), then finish drilling out the hole with a Forstner bit. That will clear out any "wedged" bits of wood created by the boring bit. Then you should be able to close the crack completely. A bit of glue - clamp it up - let it dry.
    RSBBass, HeavyDuty and 96tbird like this.
  3. 202dy

    202dy Supporting Member

    Sep 26, 2006
    The threaded taper requires a proper pilot hole.

    Spade bits are for rough work that will be hidden, like boring holes in studs to run romex. Even for that kind of work you're better off with an auger bit with a lead screw.

    Follow Turnaround's advice. You will need to create a couple of clamping cauls in order for the clamp(s) to work across the headstock. Otherwise, the clamp foot will slide off the work.

    Do a dry run or two to make sure the clamp and cauls work right and that you can apply them in a timely fashion. Finding out that the clamp is slipping off the workpiece isn't something you want to find out only after the crack is full of glue.
    HeavyDuty and 96tbird like this.
  4. Thanks, that was what I was thinking. Hopefully I can find a bit locally.

    Yeah, disappointed in this type of spade bit. Seems like a flawed design.
  5. 202dy

    202dy Supporting Member

    Sep 26, 2006
    The design is good when used for the right application. It's also good for the price. Spade bits just aren't designed for fine woodworking.

    Guitar building and repair work is nothing if not fine woodworking.
    TomB and 96tbird like this.
  6. The LIKE is not because I liked what happened, but because I just learned how not to do this very same thing that I’ll be doing soon.
    Thank you and sorry it happened. Hope you get her glued up OK.
    S-Bigbottom likes this.
  7. Teacher


    May 3, 2012
    I threw my spade bits years ago. Yeah they're cheap, but the day I damn near ripped tendons in my shoulder when I was drilling through 1" plywood, standing up, and it hit a knot and lifted me off the floor, I scrapped them. They're for fairly rough and quick work and work best on softwoods.
    RSBBass and bolophonic like this.
  8. JRA

    JRA my words = opinion Supporting Member

    could have been worse! we learn. good luck with your repairs! :thumbsup:

    in advance of your repair work: congrats on your 5'er! ;)
  9. rllefebv


    Oct 17, 2000
    Newberg, Oregon
    I feel your pain!!! Same exact drill bit from Home Depot... I drilled about a half dozen test holes in a scrap piece of maple to get the correct feel and setup... the holes came out clean, and I was fairly confident. As soon as I started on the real thing, “CRACK”!!!


    Not the cleanest break, but I was able to widen and clean the splinters... installed dowels through the sides for a strong repair. Happily, this bass is my main player for the past six months...

    FWIW, the next day, I purchased a proper bit from the tool crib at work :D

    bolophonic likes this.
  10. It's the screw part of the bit that will split your headstock. Those bits will work fine if you drill a pilot hole the same size as the screw part of the bit. Also, use a drill press. Don't try this with cousin Goober's cordless drill.
  11. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    what the heck even is that thing?

    spade bits look like this:

    of course that thing with the threaded conical point will wedge apart and split hard wood, i couldn't imagine it doing otherwise.
    96tbird likes this.
  12. Gilmourisgod


    Jun 23, 2014
    Cape Cod MA
    Spade bits work great for whacking ragged holes in 2x4’s, which is what they were designed to do. Even then, they can catch and split out, or torque your wrist painfully. It’s a crude tool that was probably designed for use in an old school brace and bit, my grandfather had a whole set with the same screw points. Forstner bits aren’t cheap, but if it’s just a one time job, you could probably get away with a Harbor Freight cheapy. Don’t expect it to stay sharp for more than one or two uses though. If you plan on doing this a lot, suck it up and get a good quality forstner set, or just the single size you need. Sorry for your pain, I’ve made my share of similar eff-ups!
    fhm555 likes this.
  13. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    @sublimate .....Screw point spade bits are intended to be used on large pieces of timber. I've used the type @walterw pictured for decades on thin pieces of wood with no problems. The holes is not as neat as a Forstner bit due to runout but they're cheaper and cut quicker. The trick is to drill an 1/8" pilot hole through the work piece and then drill half the hole from either side. This prevents the splintering on the breakout side that occurs when the hole is drilled all the way through from one side. I use the same technique for Forstner bits when I can't have a firm backup with a piece of scrap wood.
    Last edited: Nov 23, 2018
    walterw and Gilmourisgod like this.
  14. megafiddle


    May 25, 2011
    Latex (surgical) tubing is great for clamping complex shapes. The clamping force can be enormous, and you can control it by how much you stretch the tubing while wrapping it around the joint.

    You begin the wrap by wrapping the first turn over the free end to secure it. Then stretch the tubing while wrapping it along the joint. Finish by tucking the very last wrap under the adjacent previous wrap.

  15. byacey


    May 16, 2008
    Alberta, Canada
    Those spade bits with the threaded brad haul itself through the wood in an aggressive manner; they are self feeding. Little to no pressure is required, so there is little control over the feed rate and how it cuts. The other problem is when they break through the back side of the work piece, there is always blowout splintering.

    If a forstner bit is unavailable, the spade bits in post #11 could be used, but I would drill a 3/32" hole first for a pilot. Then using a drill press, clamp the work with some scrap wood backing underneath, clamp to the table, drill halfway through using a very light feed. Then flip it over and finish drilling from the opposite side.
    Clamping the work solidly to the table is a necessity. Trying to do this free-hand will only end in disaster.
    202dy likes this.

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