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Thread: Reduce Diameter of Dowel by 1mm ?

  1. #1
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    Default Reduce Diameter of Dowel by 1mm ?

    Got a section of broken carbon-fiber SUP paddle shaft that I want to make into a cane.

    The handle needs to be shaved down by almost exactly 1mm (2mm diameter total) to fit inside that shaft.

    The section in question is straight - although somebody with better eyes than mine may observe that the shaft actually tapers slightly as it approaches the tip.

    Last time I did this, I eyeballed it and kept shaving until I got a fit - but it was touch-and-go and I suspect that I got lucky.

    A lathe is both unavailable and (I think...) impractical considering the crook.

    Can anybody suggest a more precise method than just eyeballing/freehanding it?

    20180626_113343_proc.jpg
    Last edited by PeteCress; 06-26-2018 at 10:45 AM.

  2. #2
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    You don't need 'precise'. Not worth the fuss. Just whittle until it slips in, then glue with epoxy (colored gray or black if you wish).
    David G
    Harbor Woodworks
    https://www.facebook.com/HarborWoodworks/

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  3. #3
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    This is the way I would do it:
    Quote Originally Posted by David G View Post
    You don't need 'precise'. Not worth the fuss. Just whittle until it slips in, then glue with epoxy (colored gray or black if you wish).
    The tool that would take far longer to design and build is a witchet. Other names or similar tools include chair makers rounder and tenon cutter.

    This describes an iterative process to dial in a home built tool: http://lumberjocks.com/llwynog/blog/28687

    This one might be small enough to fit inside the handle:
    EDIT: It is out of stock, and seems to have been discontinued
    https://www.japanwoodworker.com/prod...rounding-plane


    EDIT:
    I found one more site with a comment I can't resist, http://toolmonger.com/2007/12/24/old...unding-planes/
    If buying perfect 1/2” dowels is just too convenient and easy, you can slow production down the old school way by using a dowel rounding plane. It works much like a pencil sharpener, only bigger and significantly slower. This one from the Japan Woodworker Catalog recreates an 18th century Scottish design. ... Note: be prepared to invest some serious time in this project.
    Dave
    Last edited by MN Dave; 06-26-2018 at 12:22 PM.
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  4. #4
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Of course you can use a cordless drill.
    Just Google "tenon cutters".
    Or this as an example: https://www.northerntool.com/shop/to...yAAEgInG_D_BwE

    There is always a way to spend more money!

    Shaving by hand and eye, then epoxy is my choice also.

  5. #5
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Hammer it through a hole the right size you have drilled in a piece of steel. Is'nt that how dowel was made originally?
    'C'est la vie' say the old folks it goes to show you never can tell

  6. #6
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Quote Originally Posted by David G View Post
    You don't need 'precise'.
    I went with that, and guess I got lucky again.

    This time, though, I printed a circle exactly the diameter I wanted and glued/centered it on the end of the crook.

    Then I set a RotoZip to as close to 1mm penetration as I could and cut a series of grooves in the shaft.
    Probably should have used a router (more precise), but did not have any bits that narrow on hand
    20180626_131621.jpg
    20180626_131537.jpg


    Used a box cutter to cut into the shaft at the hip and trimmed from the nearest groove to the hip.

    Then I used a sort-of rasp to work it all down to the grooves and printed circle.

    My biggest worry was winding up with an off-center shaft in the reduced-diameter area - and the grooves and printed circle seem to have addressed that.
    20180626_133304_proc.jpg
    20180626_133335_proc.jpg

    20180626_133503_proc.jpg

    Right now, I have a reasonably-good friction fit. Might 'poxy it, might not. Another option would seem to be putting something on the wood to make it swell a bit - "Chair Lock"?

    I *do* like the idea of MnDave's various Rounding Planes..... and I think I will have to try the home-made jig as per http://woodgears.ca/dowel/making.html.
    Last edited by PeteCress; 06-26-2018 at 01:03 PM.

  7. #7
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    If the other end of that tube is open, you could do the hammerhead technique. Cut a slim slot in the end of the handle, and make a small tapered wedge. Insert just a bit of the wedge in the end of the slot, then stick the assembly in the tube. Take a long rod, and a hammer, and slide the rod down the tube from the crutch tip end. Stabilize all, then hammer in the wedge with the rod and hammer. Note this is a 'one-way' trip -- removal will be a bear if you do it right.

    If it were mine, and replacement/disassembly may be needed, I would run a steel cable thru the shaft with a threaded bolt affair to tighten it. Crutch tip can hide the hardware/crosspin or whatever you use to make it happen. Is overall lightness the goal, or just fixing a broken cane. Or maybe product placement/advertising sponsorship?

  8. #8
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Quote Originally Posted by Chip Chester View Post
    Is overall lightness the goal, or just fixing a broken cane. Or maybe product placement/advertising sponsorship?
    Lost the cane I made out of the tip of a broken windsurfer mast.

    Guy at the shop where I maintain some IP cams had this broken SUP paddle shaft...

    If it hits something, dunno whether the cane or the something breaks; but for just plain cane use by somebody who weighs 200#+, it is impressively light/rigid/strong - and, compared to the 1 1/16th" hickory canes I use, the diminished swing weight is *really* impressive.

    20180626_155133_proc.jpg

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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Crimping a decorative ferule between the two materials could be nice. Perhaps a winding, like a Fly rod joint.
    PaulF

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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Quote Originally Posted by PeteCress View Post
    Right now, I have a reasonably-good friction fit. Might 'poxy it, might not. Another option would seem to be putting something on the wood to make it swell a bit - "Chair Lock"
    That might work well enough alone. If it isn't quite tight enough, you can still use epoxy and will have the benefit of a reduced tendency to shrink and break the epoxy bond.

    I found several versions of wood swellers online and the safety data sheets include a glycols and one has some amine as well. Swel-Lock is dipropylene glycol, and Chair-Loc has propylene glycol, triethanolamine and some solids. I don't think that the particular glycol makes much difference, even plain automobile antifreeze. You could even epoxy the handle and then pour some glycol in the other end. It will soak into the wood and swell it. No particular need to let the epoxy cure since the only epoxy exposed to the liquid will be the bit that is pushed up around the end of the handle inside the shaft.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Quote Originally Posted by MN Dave View Post
    This is the way I would do it:
    The tool that would take far longer to design and build is a witchet. Other names or similar tools include chair makers rounder and tenon cutter.

    This describes an iterative process to dial in a home built tool: http://lumberjocks.com/llwynog/blog/28687

    This one might be small enough to fit inside the handle:
    EDIT: It is out of stock, and seems to have been discontinued
    https://www.japanwoodworker.com/prod...rounding-plane


    EDIT:
    I found one more site with a comment I can't resist, http://toolmonger.com/2007/12/24/old...unding-planes/

    Dave
    with an apropriately sized reamer (chair models are common) it's easy to make one in the shop with said reamer, a drill & a block of hardwood for the taper (maple is nice) and a 3.25" power planer blade (the resharpenable kind)

  12. #12
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Fly rod joint or a turk's head over the joint. That's what I'd be going for.
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Fly rod joint or a turk's head over the joint. That's what I'd be going for.
    As PuulF also mentioned, this is a really good idea and usually far more than just cosmetic when you're sticking a plug into a carbon fiber tube and putting pressure on it. The tubes have a tendency to split if they get some lateral pressure at the joint. A metal ring around the beginning of the tube, a varnished wrapping of twine or thread, or something like carbon or fiberglass roving strands going around the tube's end and saturated will work.

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    Default Re: Reduce Diameter of Dowel by 1mm ?

    I don't have an answer to the question, but have a question of my own. The SUP paddle broke. That suggests to me that its strength is suspect. If it was me, or a close friend or family member who was going to use the cane, I would not trust the strength of a piece that had already broken once from what I imagine were similar stresses and strains. I am no engineer, but question the strength of this to support someone who is relying on its strength. To the extent a lightweight cane is important, I would seek a lightweight cane already made for the purpose. To each his own, though, so I wish you the best of luck whatever you do.

  15. #15
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Quote Originally Posted by ThomRose View Post
    I don't have an answer to the question, but have a question of my own. The SUP paddle broke. That suggests to me that its strength is suspect. If it was me, or a close friend or family member who was going to use the cane, I would not trust the strength of a piece that had already broken once from what I imagine were similar stresses and strains. I am no engineer, but question the strength of this to support someone who is relying on its strength. To the extent a lightweight cane is important, I would seek a lightweight cane already made for the purpose. To each his own, though, so I wish you the best of luck whatever you do.
    A SUP paddle breaks from bending, probably could also be attributed to buckling. Carbon fiber can also be badly damaged by impact, which will result in a bending failure soon after it gets bruised. There may be some damaged area around the break, so if that is cut away, the rest of the shaft should be OK.

    A cane is loaded mostly in compression, which is much less damaging than bending.

    Todd and PaulF have a good point about reinforcing the ends with a ferrule.

    I thought I saw someone mention a plug at the tip of the cane to strengthen it against impact, but I am too lazy right now to reread 13 posts. Anyway, since the end is hidden in a rubber bumper, it would be easy enough to cast a crude plug in the end with some slightly fluid thickened epoxy, using the rubber tip to keep it from oozing until it cures.
    Last edited by MN Dave; 06-28-2018 at 12:07 PM. Reason: typos, I'm good at making typos
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  16. #16
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Quote Originally Posted by ThomRose View Post
    ...the SUP paddle broke. That suggests to me that its strength is suspect. If it was me, or a close friend or family member who was going to use the cane, I would not trust the strength of a piece that had already broken once from what I imagine were similar stresses and strains. I am no engineer, but question the strength of this to support someone who is relying on its strength.
    I am no engineer either, but if you could feel this thing I think any doubts about it's strength under conventional cane use would go away completely..... This thing is strong.

    OTOH, if used to wack somebody in the shin, I think there is a legitimate question as to whether the shin bone or the cane would break.

    Not so with the one that I made from the tip of a broken 80%-carbon windsurfing mast: the shin loses every time - that thing was seriously strong....

    OTOOH, used to support one's body weight leaning on the middle of the cane when getting up off the ground, it seems adequate...but "Seems" is the operative word.

    Todd's suggestion to reinforce the interface between tube and handle rings true to me and I will do that next time around - using a few wraps of carbon that I have left over from reinforcing a windsurfer mast for use on my dearly-departed Hawaiian-style outrigger.
    Last edited by PeteCress; 06-29-2018 at 04:55 PM.

  17. #17
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    Default Re: Reduce Diameter of Dowel by 1mm ?

    Carbon fibers gonna want to fray...loosen. I’d tightly whip finish twine 3/4 either side if the joint and cover with epoxy. I have a little motor for slowly turning flyrods as the epoxy sets up on the wraps.

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