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Thread: Shaping plane for rounding a spar

  1. #1
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    Default Shaping plane for rounding a spar

    In Arthur Ransome's Swallowdale, Captain Flint and John make a new mast for Swallow from a Norway pine. They rough it out with an adz and then shape it using something they call a 'shaping plane'. Here's the description from the book:

    "The plane was curved, so that it would take shavings off a rounded surface as evenly as an ordinary plane takes shavings off a plank."

    I know the word 'shaping plane' is very generic, but I'm wondering what type of plane they might have used? Ransome was an experienced boatbuilder, and his audience was no doubt so familiar with hand tools that no further description was necessary.

    Having just spent a long, long time over a similar task using a spokeshave, I'm wondering if this mysterious 'shaping plane' would be a better tool for the job.

    When the book says 'the plane was curved', I'm guessing that both the plane bottom and blade were concave -- rounded slightly from side to side -- so it would fit around a spar, and take off a wider shave. I'm guessing such planes were available in different shapes, since you'd want just a slight curve for a big mast, but a tighter curve for a boom, or smaller mast.

    The problem with a straight blade, like a spokeshave, is it takes off such a narrow shave on a curved piece of wood. You need to take many, many strokes to smooth it all around.

    Problem is, I've never seen such a plane. Anyone have a photo to share?

    Since my spar is not a straight mast, but a curved boomkin, I'm now on the hunt for a concave spokeshave, preferably with a wooden body. The curve has to be big enough for a 2-3" spar, not a skinny chair leg. Anyone got an extra one they want to sell? I think these were fairly common back in the day.

    More details, photos, and even a video of this lengthy task: Whole Lotta Round

  2. #2
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    Default Re: Shaping plane for rounding a spar

    LEe valley tools sells a spokeshave with a concave sole and blade. There are alot of them around. Normally you build your own though. Custom sized to the spar. OR close enough that you can use it for a range of spars.
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  3. #3
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    Default Re: Shaping plane for rounding a spar

    Quote Originally Posted by Sailor View Post
    LEe valley tools sells a spokeshave with a concave sole and blade. There are alot of them around. Normally you build your own though. Custom sized to the spar. OR close enough that you can use it for a range of spars.
    The ones you can buy today, including from Lee Valley, are aimed at chair makers, I think. The curve is too tight to fit around a 2-3" spar.

  4. #4
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    Default Re: Shaping plane for rounding a spar

    They used one of these. You can make your own from an old woodie coffin smoother or jack plane.

    You wont be able to modify a wooden spoke shave 'cos of the way the blade is made. You could convert a coffin smoother to make a compass spar plane for the inside curve though. Unusual but possible.
    It really is quite difficult to build an ugly wooden boat.

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  5. #5
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    Default Re: Shaping plane for rounding a spar

    There's a thread showing those planes around here somewhere. Bob Smalser figures conspicuously therein. Someone must be able to find it.

  6. #6
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    Default Re: Shaping plane for rounding a spar

    Nick: that looks about right. Gotta be easier to use than a spokeshave. I have a plane I could modify... I wonder if Dunbar explains how to sharpen a curved blade? With a file, maybe?

  7. #7
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    Default Re: Shaping plane for rounding a spar

    Here's an old internet article on how to make one. Woodenboat has a more detailed article if you search the index.

    I use a tablesaw cove cut for both, but if that's too scary you can do the same using gouges. You have to rough-sand on the PVC pipe anyway, as the cove cut doesn't make a perfect circle. You sand the plane sole and blade at the same time to get matching arcs, then increase the bevel on the iron separately.

    http://www.wkfinetools.com/contrib/b...sparPlane1.asp









    Except it's not quite as straightforward as advertised, as coving the sole opens the mouth too wide for a fine shaving, requiring a graving piece be added and pared to conform to sole, mouth and throat angles:



    There are a couple of ways to do that. I find a Forstner bit and a lathe-turned plug the easiest.

    Last edited by Bob Smalser; 03-04-2012 at 04:22 PM.

  8. #8
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    Default Re: Shaping plane for rounding a spar

    I believe that one sharpens those curved irons with a "Slip stone". In much the same manner one would sharpen an in-cannel gouge.

  9. #9
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    Default Re: Shaping plane for rounding a spar

    Quote Originally Posted by Bob Smalser View Post
    Here's an old internet article on how to make one. Woodenboat has a more detailed article if you search the index.

    I use a tablesaw cove cut for both, but if that's too scary you can do the same using gouges. You have to rough-sand on the PVC pipe anyway, as the cove cut doesn't make a perfect circle. You sand the plane sole and blade at the same time to get matching arcs, then increase the bevel on the iron separately.

    http://www.wkfinetools.com/contrib/b...sparPlane1.asp
    Wow. I asked for it, I got it! Thanks, Bob. Great article.

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    Default Re: Shaping plane for rounding a spar

    Quote Originally Posted by Bob Smalser View Post
    Woodenboat has a more detailed article if you search the index.
    #192 Starting on page 72.

    Written and photographed by....Bob Smalser, thanks Bob.
    Steve Martinsen

  11. #11
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    Default Re: Shaping plane for rounding a spar

    Reading the blog post it sounds like the problem isn't so much rounding the spar as taking the oversized round spar down to final dimensions. I think it would probably be a lot faster and a lot easier to keep the round uniform if you just started with a square of the finished dimensions, or very slightly oversize if the fit needs to be absolutely perfect. Even if it does need a perfect fit, you could just leave a small portion at the inboard end 1/16" oversize and save a lot of time. If you carefully get your square cross section correct then I think you'd find it relatively easy to keep things the right dimension.

    I assume what John did for Swallow's mast was shape it with the adze to a square cross-section of the right dimensions and taper, then 8 side it, maybe even 16 side it, and only then use the spar plane to bring it to round.

    I recently found a couple of "spar" planes (probably actually made for furniture) and used them to take some 1.5 - 3" spars to round after 16 siding them. This worked great, but I really can't see using one to make a round spar into a smaller round spar because your blade radius is never going to be exactly the same as the spar, especially if there is any taper. Like you did, you'd have to keep checking against a template. Plus it won't work on the concave side of your curved boomkin anyway unless you had some kind of compass plane with a concave blade, and that sounds like a nightmare (challenge?) to make, and only suitable to a very specific job.

    Of course, I only started using these planes a month ago, so I might be completely wrong and spar planes were/are actually used to round the spars from a square blank, but that sounds inefficient to me.


  12. #12
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    Default Re: Shaping plane for rounding a spar

    Quote Originally Posted by andykane View Post
    Reading the blog post it sounds like the problem isn't so much rounding the spar as taking the oversized round spar down to final dimensions. I think it would probably be a lot faster and a lot easier to keep the round uniform if you just started with a square of the finished dimensions, or very slightly oversize if the fit needs to be absolutely perfect.
    Yes, someone else wrote me privately about this and I think you are both right. I erred too much on the side of having plenty of 'extra', and have paid for it with a lot of hard work. On the second spar, I will definitely cut it a lot finer!

  13. #13
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    Default Re: Shaping plane for rounding a spar

    Quote Originally Posted by andykane View Post
    Reading the blog post it sounds like the problem isn't so much rounding the spar as taking the oversized round spar down to final dimensions. I think it would probably be a lot faster and a lot easier to keep the round uniform if you just started with a square of the finished dimensions, or very slightly oversize if the fit needs to be absolutely perfect. Even if it does need a perfect fit, you could just leave a small portion at the inboard end 1/16" oversize and save a lot of time. If you carefully get your square cross section correct then I think you'd find it relatively easy to keep things the right dimension.

    I assume what John did for Swallow's mast was shape it with the adze to a square cross-section of the right dimensions and taper, then 8 side it, maybe even 16 side it, and only then use the spar plane to bring it to round.

    I recently found a couple of "spar" planes (probably actually made for furniture) and used them to take some 1.5 - 3" spars to round after 16 siding them. This worked great, but I really can't see using one to make a round spar into a smaller round spar because your blade radius is never going to be exactly the same as the spar, especially if there is any taper. Like you did, you'd have to keep checking against a template. Plus it won't work on the concave side of your curved boomkin anyway unless you had some kind of compass plane with a concave blade, and that sounds like a nightmare (challenge?) to make, and only suitable to a very specific job.

    Of course, I only started using these planes a month ago, so I might be completely wrong and spar planes were/are actually used to round the spars from a square blank, but that sounds inefficient to me.

    Yes, you use the spar pane for final finishing after repeatedly taking the corners off. There is more control of shape that way.
    Similar planes were used in shop joinery, not for furniture, but for shaping banister rails for stairs and landings.
    It really is quite difficult to build an ugly wooden boat.

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  14. #14
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    Default Re: Shaping plane for rounding a spar

    Quote Originally Posted by andykane View Post
    Of course, I only started using these planes a month ago, so I might be completely wrong and spar planes were/are actually used to round the spars from a square blank, but that sounds inefficient to me.
    Today spar planes are useful to fair a birdsmouth spar the moment the hose clamps are removed.

    But you need them in two or three decreasing sizes to accommdate the tapers on small spars and they still have to have tight mouths to take fine shavings. They also add a step to the glueup process to the staves are all oriented in the same grain direction for easy planing.

  15. #15
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    Default Re: Shaping plane for rounding a spar

    Well, I ended up by re-squaring the spar. It's just too hard to taper a round spar unless you happen to have the right tool.

    I re-squared it and then tapered it with a normal flat plane (spokeshave, actually), and then trimmed off the corners to make it an octagon. I think the octagonal shape is nicer than round for this type of spar, anyway.

    A whole lot of work, but the result was worth the effort, I think.

    Finally ready for varnishing. Blow-by-blow details in my blog post.


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    Default Re: Shaping plane for rounding a spar

    That's a pretty bendy looking spar..... Looks more like a tiller.
    I hope you're not going to use that in any windy conditions that might put your life or other's lives in jeopardy..... Those knots, and grain run out are pretty...... Severe.

  17. #17
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    Default Re: Shaping plane for rounding a spar

    I have one similar to those shown. Used it on a mast and spars that I rounded from square blanks. It was a fun tool to have and use, but judicious use of a regular, flat smoothing plane to create many small flats, such as 64ths or 128ths, also worked pretty well. Either way, you likely will follow up with coarse sandpaper on a rounded block, and to some extent that can take the place of a rounded plane bottom if you don't have one.

  18. #18
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    Default Re: Shaping plane for rounding a spar

    Quote Originally Posted by Mrleft8 View Post
    That's a pretty bendy looking spar..... Looks more like a tiller.
    I hope you're not going to use that in any windy conditions that might put your life or other's lives in jeopardy..... Those knots, and grain run out are pretty...... Severe.
    I'm pretty sure I could lift the boat with that spar. Hickory is pretty strong and the lamination makes it stronger. It's half of a boomkin for a 50 square ft mizzen, so the load is mainly compression. I hope it's up to the job.

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