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Thread: spade bits

  1. #1
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    Default spade bits

    I have been sorting out some of the tools which Dad had in his possession: his 'spade bits' which must be well over 50 years old, then some.
    He has multiple bits in the same size with many having a wider centre point: see photos for comparisons.

    Im curious as to why this may be so. Just differing styles perhaps?


    IMG_4299.jpg

    IMG_4300.jpg
    Last edited by Bernadette; 09-16-2022 at 03:17 AM.

  2. #2
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    Default Re: spade bits

    I have a similar variety. I think it can only relate to the diameter of a pilot hole.
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  3. #3
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    Default Re: spade bits

    I wonder if the oddly filed tip might be for drilling/starting a hole at a steep(shallow?) angle? not square .
    can't think of anything else, never seen anything like it

  4. #4
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    Default Re: spade bits

    Never seen those for sale but I've ground many an Irwin Spadebit to a custom profile/size for specific task. The wide pilot'd be useful f'rinstance making a little hole bigger w/o chatter or wandering. Other ways exist but lacking a right-size dowel or plug this is fast & relatively easy.
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  5. #5
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    Default Re: spade bits

    ahhhhhh,,,chattering and wandering during widening follow up! of course !!

  6. #6
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    Default Re: spade bits

    I don't think that they are for counter boring a pilot hole, as the center point is flared, not constant diameter.
    Maybe they are specifically for drilling into hard wood, effectively boring the hole in two stages.
    It really is quite difficult to build an ugly wooden boat.

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  7. #7
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    Default Re: spade bits

    Could be an adaptation of the old deck dowel bits bits we used to use??

  8. #8
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    Default Re: spade bits

    Quote Originally Posted by Chippie View Post
    Could be an adaptation of the old deck dowel bits bits we used to use??
    Like this?
    DSC04040.jpg
    It really is quite difficult to build an ugly wooden boat.

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  9. #9
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    Default Re: spade bits

    Quote Originally Posted by Peerie Maa View Post
    Like this?
    DSC04040.jpg
    Nick, Chippie-were those made special in the boatyard?

  10. #10
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    Default Re: spade bits

    I doubt it. There would be enough demand for a firm like Marples to make them. That one is a Marples & Son. For bunging wood decks laid on iron beams (and possibly for composite hulls), the stem was threaded to match the treads in the holes in the beam or frames, so the bit wound itself in and out.
    As I said in post #6 above, I don't think the spade bits are for boring for bungs. The middle point is too complicated, it does not need the point, and the flare at the point would be counterproductive. The narrow one in the OP is even less likely.
    It really is quite difficult to build an ugly wooden boat.

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  11. #11
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    Default Re: spade bits

    Yes, and of course to different dimensions.

    I still have one I last used when laying wood decks in the 50's.


    They could be purchased too in certain ironmongers.

  12. #12
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    Default Re: spade bits

    [QUOTE=Peerie Maa;6730863]I doubt it. There would be enough demand for a firm like Marples to make them. That one is a Marples & Son. For bunging wood decks laid on iron beams (and possibly for composite hulls), the stem was threaded to match the treads in the holes in the beam or frames, so the bit wound itself in and out.

    Nick I cannot see any threads on that shank?

    There certainly isn't any on mine.

    The decking I laid on open beams was spasmodic repair work and I encountered none where it was held by bolts inserted downward into a threaded beam?

  13. #13
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    Default Re: spade bits

    [QUOTE=Chippie;6730882]
    Quote Originally Posted by Peerie Maa View Post
    I doubt it. There would be enough demand for a firm like Marples to make them. That one is a Marples & Son. For bunging wood decks laid on iron beams (and possibly for composite hulls), the stem was threaded to match the treads in the holes in the beam or frames, so the bit wound itself in and out.

    Nick I cannot see any threads on that shank?

    There certainly isn't any on mine.

    The decking I laid on open beams was spasmodic repair work and I encountered none where it was held by bolts inserted downward into a threaded beam?
    Perhaps I should have typed "When", not "For". That bung bit of mine is sized for counter boring for 3/8 coach bolt heads into wood.

    This on from a auction site is threaded.
    Last edited by Peerie Maa; 09-25-2022 at 06:32 AM.
    It really is quite difficult to build an ugly wooden boat.

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  14. #14
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    Default Re: spade bits

    I showed Dad the photos of the differing bits today. He couldn't remember why he specifically had the bits with larger centre bores.
    Unfortunately, time has taken it's toll on his memory. I wish I had got his oral history well before now.
    He did say however that the bits with sharp centre bores would be much better to use!!! Kind of ironic given that I doubt if Dad would have any tools not worth using or ones that he didn't use.

  15. #15
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    Default Re: spade bits

    Quote Originally Posted by Peerie Maa View Post
    Like this?
    DSC04040.jpg
    Bernadette the bit shown was as the name implies a "Dowel" bit.
    The blunt stub was inserted into the hole that had been drilled to accept the holding down bolt that secured the wood decking to the steel deck/angle bar it lay on.

    I must relearn how to post photo's.


    PS.
    I am in awe of that boat and its magnificent lines especially the top sheer at the Gunwhales.
    Now for the question you're not obliged to answer.

    Nick and I have a difference of opinion as how to obtain that.

    I say it's engineered if you know how.

    He say's it's "eyeballed" (Unless he has changed his mind and accepted I am right.)
    Last edited by Chippie; 09-29-2022 at 07:11 AM.

  16. #16
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    Default Re: spade bits

    Quote Originally Posted by Chippie View Post
    PS.
    I am in awe of that boat and its magnificent lines especially the top sheer at the Gunwhales.
    Now for the question you're not obliged to answer.

    Nick and I have a difference of opinion as how to obtain that.

    I say it's engineered if you know how.

    He say's it's "eyeballed" (Unless he has changed his mind and accepted I am right.)
    I suspect that you are misunderstanding whatever it was that I posted.
    On a hull of the size that Bernadette is building the Yacht Architect will have designed the shear, and then, if a full size lofting was drawn, rather than just a scrieve board, the builder will loft the sheer in profile and plan.
    Then, when the molds or frames are erected, a batten will be hung to confirm the shear line. It will then be checked by eyeballing. That should ensure that the two 2D lines work together in harmony in the round. On some hulls, with a full bow, or with flare, what looks fair in 2D can create a subtle but visible powder horn hump in 3D.

    These days, with CAD visualizing the hull in 3D from any direction, it is far less likely that the builder will have to make any adjustments to the lines.
    It really is quite difficult to build an ugly wooden boat.

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  17. #17
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    Default Re: spade bits

    "I would set the height at stem, stern and measure up to set the depth in the middle of the length, mark these heights on the shear streak and wrap a batten around it. Then stand well back and sight it and adjust until eye sweet. I read that the commissioning owner would tell the builder what the key dimensions should be so the builder knew what he was aiming at."

    That is what I read Nick when we were discussing on the Coble Thread.

    I still thik there is an easier way.

    I don't want to intrude on Bernadette's Thread so i'ii leave it at that.

  18. #18
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    Default Re: spade bits

    Quote Originally Posted by Chippie View Post
    "I would set the height at stem, stern and measure up to set the depth in the middle of the length, mark these heights on the shear streak and wrap a batten around it. Then stand well back and sight it and adjust until eye sweet. I read that the commissioning owner would tell the builder what the key dimensions should be so the builder knew what he was aiming at."

    That is what I read Nick when we were discussing on the Coble Thread.

    I still thik there is an easier way.

    I don't want to intrude on Bernadette's Thread so i'ii leave it at that.
    That is applicable to boats like cobles, Shetland Models and other small craft built without plans.
    Bernadette's yacht is a different kettle of fish entirely. You are right, stop the thread drift.
    It really is quite difficult to build an ugly wooden boat.

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