low angle double paddle build

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Rabbit
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low angle double paddle build

Post by Rabbit » Mon Sep 22, 2014 2:27 am

hi all :)

well, i've started the build, so here's what i have so far:

for the shaft i've used birds mouth construction. the strips are 13mm wide and 6mm thick. i used a 90deg v bit on the router table to get my groove. i alternated between paulownia strips and wrc.

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i used titebond iii to glue this up, mainly because i had it on hand and it has a longer open time, since i anticipated putting such a long shaft together would take longer. it was tricky, because the strips are to use jim dodd's term "wet noodles". using tape at one end i pieced together the strips, taped around the bundle , grabbed the end in one hand and with my other hand gently shook the bundle while squeezing and moving my hand a little way down the shaft, taped up that bit and continued this process, taping as i went till the whole shaft was formed. at this point the glue acts as a lubricant and the flexible strips can slide against each other. if you wanted to make a bent shaft, it's pretty easy to do. to keep it strait is more difficult. i added more tape points to clamp the pieces together, sighting down the shaft and rotating to keep it strait, then putting it inside some 90mm pvc tube on a flat surface to dry. if you have access to some long angle iron or metal u tube, taping the shaft to that after taping around the shaft itself would be a better option.

next was the blanks for the blades. i made two of them. i cut 40mm wide strips 10mm thick about 900mm long (too long but that's the length of the material i had at hand) and clamped them together on a flat surface.

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that takes care of the initial pieces, now for the blade profile. i couldn't easily find a low angle blade pattern online. the next best thing was to find a web site with images of paddles and try using that. i've used grey owl's tempest paddle as my template. now, you could just print this out and put it on a projector to the right size against some card board and trace around it. if you have access to the right software you could import the image and trace around it to create a vector image and print it out to full size (or export to a cam router). i did it the slow and painful way. i printed out the image slightly enlarged so that the edges were still reasonable smooth. since grey owl have a central lamination , this makes a good reference point. draw a centre line down the middle of the central lamination, then mark 90deg lines at equal intervals along that line. in my case that was every 5mm. measure the distance from the centre line to the edge of the blade above and below the centre line and record for each of the intervals to create an offset table. then scale up these values by the scale of your print based off the published paddle specs. in my case that worked out to be 2.6. because of the small scale i ended up with a flat line where there should have been a shallow curve, but that's fine, it's just a guide.

i plotted my points onto a sheet of cardboard and then used french curves and battens to fair the curves. it's basically the same process you would use to make your station moulds.

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that's as far as i have gotten so far. will post more as i progress. :tu

Rabbit
Posts: 121
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Location: Downunder

Re: low angle double paddle build

Post by Rabbit » Tue Sep 30, 2014 5:29 am

shaft:
here's the shaft after glassing and trimming to size (2100mm).

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now, you could probably leave it octagonal, sand it smooth and round the edges for the purposes of glassing, but i chose to sand it round. it was glassed with 6oz glass cloth tape a little longer than the length of the shaft which gave me a 25mm overlap. i used a wet layup, so a coat of epoxy on the bare timber, and while still wet applied the edge of the tape along the length of the shaft, and using a foam roller to wet out the glass. once tacky, a second coat is added and allowed to dry to hardness. this gives you a textured shaft with a sharp edge of hard glass along the length. once hardened, you can sand the edge to feather it into the shaft to give you a nice smooth seam. the shaft is sanded lightly to give it a tooth, and a final thin film of epoxy is applied and the seam disappears, as well as the weave filled. i used 6oz glass mainly because that's what i had on hand and the edge of the tape is easier to deal with than cutting strips from cloth.

here's what the cross section of the shaft looks like:

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the light at the end of the tunnel gives you an indication that it came out nice and strait. the alternating wrc and paulownia made a nice contrast. if you can't get paulownia then basswood would probably do, or maybe poc if you can get it. amazing how light it feels.

blades:

i cut out my template and cut small notches at the ends where the centre line is. this makes it easy to line up with the centre line.

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i traced out the template on my boards and removed most the excess timber with a small saw. if you have a fine toothed band saw or a scroll saw you could use that. i was hesitant to use the jig saw because the blade is fairly coarse and might rip and tear the soft timber.

the rest of the material was removed to the line with a disk sander for the convex curve (most of the blade) and a small belt sander clamped upside down to a work bench for the concave curves near the shaft end of the blanks. a drum sander would probably be the ideal tool to do the whole blank if you have access. a curved soled spokeshave is another option if you have the template pattern traced on both sides to get a nice square edge, but be mindful of the grain to avoid tear outs.

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Jim Dodd
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Re: low angle double paddle build

Post by Jim Dodd » Tue Sep 30, 2014 7:19 pm

I like the shaft assembly !

Jim
Keep your paddle wet and your seat dry!

Rabbit
Posts: 121
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Re: low angle double paddle build

Post by Rabbit » Tue Oct 14, 2014 8:00 am

welp, the forum has been a little quiet, so i thought i'd post a bit more of the build. the weather hasn't been great, so i've only managed to get a single coat of epoxy on the glass for the blades, so no pics of that yet, but here's what else i have. :wink

shaft:
i cut a slot in the shaft 100mm long using my jig and a flexible flush cut saw:

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ok, ya got me, this is a copy of the pic of the jig used in my single blade builds, but... its the same jig with a couple of minor mods. firstly, my shaft diameter was 35mm, which is larger than my previous shafts, so i had to move the support blocks. probably should have maybe gone with 12mm strips and 5mm thick instead of 13mm and 6mm. since my blade material was 10mm not 19mm thick i also needed to change the spacers to thicker ones. take half your shaft diameter and subtract half your blade material thickness to work out what thickness the blocks the blade slides along needs to be, and take your time with the cut. it's very easy for the blade to climb or start digging into the blocks if you aren't careful. you could also use a band saw or a drill press to cut the slots.......what ever ...floats your boat :laughing
i used a mitre box to cut 45deg angles on the ends. my slots were a tiny bit too narrow, so i adjusted them to fit with some 80 grit sandpaper glued to a tongue depressor. after you have cut your first slot, if you are keeping it as a one piece, this is the time when you have to work out if you want to feather the paddle or not and factor that in when cutting the slot in the other end. i went with unfeathered.

blades:

i used a slightly modified version of the spray paint method used by graham warren in his paddle making dvd. now, i have no idea what the edge thickness of the original blade this is patterned off is, nor where they taper off, so i took a guess. for edge thickness i went with what was specified for my single paddle blades... 3mm. i used some 3mm fine line tape.

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now, technically you should mark a line down the centre to guide you where to put the tape... but i just eyeballed it ... :laughing
spray really lightly, you don't want the paint penetrating the timber.

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generally you'd mask off where the edge tapers off at the shaft and tip, but as you can see, i didn't. i didn't know where that should be, so i marked at the shaft end where the curve transitions from concave to convex. i picked up that same angle near the tip... presumably the angle the blade is designed to be in when it's in the water.

next step was to use a spokeshave chamfer the edge of the blade down to the line, then mark the chamfered face with pencil lines to make it stand out.
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didn't know what the camber was supposed to be, so again i was just guessing. i tried clamping the blade on one side and using a spokeshave to run passes like i had with the hardwood blades of my other paddles, but it just seemed awkward. i'm not a woodworker, so i ended up going with what i knew would work for me. i epoxied the blades to the shaft, then holding the shaft with one hand used the other hand to make passes with a random orbital sander and 80 grit paper. since the wrc is soft this worked well. once i was happy with the camber i rounded all the edges with hand sanding.

left over from thicknessing the blade strips (i used a circular saw mounted upside down to a triton work centre) was some thin strips about 4mm thick. i used this to cap the ends of the shaft.

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i gave the blades a sand with 240 grit sand paper in prep for glassing.

that's all i have for you so far. once i've finished the glassing, sanding final epoxy and final sanding and varnishing i'll post the finish.

Rabbit
Posts: 121
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Re: low angle double paddle build

Post by Rabbit » Thu Oct 23, 2014 10:22 pm

ok, so it's done! :dancing

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cruiser suggested longer was better, so....
length from tip to tip: 2910ish mm
weight: 980g.

i tried to glass the edge of the blades, but this didn't work, so just the faces both side were glassed and an extra coat of epoxy was applied to the edge (4 on the edge and 3 on the blades) for abrasion resistance.

to make it easier to glass the blade, i decided to do a curved fillet between the shaft and the blade. i just smeared epoxy thickened with glue additive (aside from glue it's also used for structural fillets) along the joint. wood flour and filler thickening additive would have worked just as well. strictly speaking the correct way to do this fillet is to use masking tape on either side of the fillet to give you nice strait even lines, and a curved tool like the end of a tongue depressor to form the fillet.

the fillet was just there to make it easier to glass and has no real structural function. an alternative to filleting would be to leave a long tang on the blade to hold on to whilst cambering the blade, and then glass the blade. then you could cut off the tang and epoxy the glassed blade in place.

and here's a view of the blade camber:

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just took a guess on this one but i think it looks pretty right.
here's a view of the end of the edge tapering out to the tip:

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following the advice that drip rings might be a good idea and that rather than the plastic drip rings found on most commercially made paddles a turks head knot is the go, i looked up the knot and got a nice chart on tying it from "the international guild of knot tyers", here's what i came up with:

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the finished knot on the chart shows three strands rather than the single strand i used, so i just continued the weave till i got back to the beginning. the tag should help guide the drips back into the water course. whilst it doesn't fall down when you lift the paddle, they arn't very tight around the shaft, so if you catch them on something they can slide along the shaft. you could tack them in place with a dab of glue, but i'm going to see how they go as is. for all i know they might not even be effective. :thinking

now all i need to do is give the clear coat time to cure and then give it a go. if it turns out to be too long i can always cut it in half, trim it down and either add a ferrule or shape some hardwood to fit the inside of the shaft and epoxy together and wrap the joint with glass. :tu

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Cruiser
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Location: Bowmanville, Ontario

Re: low angle double paddle build

Post by Cruiser » Fri Oct 24, 2014 8:35 pm

Beautiful job, it's on my list of things to try .... once I get the Kipawa finished.

One point about that length, you will have to get used to the low angle stroke, and I think when you do, you will find that length will help avoid water in the boat, as most of the water handling is being done further out.

I didn't notice if you had posted this or not, but how did you round the shaft?



Brian

Rabbit
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Re: low angle double paddle build

Post by Rabbit » Sat Oct 25, 2014 3:21 am

Cruiser wrote:I didn't notice if you had posted this or not, but how did you round the shaft?
80 grit sandpaper on a sanding block. :wink

normally when you do a solid shaft you'd use a spokeshave or plane to turn a square or rectangular shaft into an octagonal, then shave down the edges again to give you 16 sides, then sand that round. with the birdsmouth you already start with it octagonal. you could sand (or plane if you were mindful of the grain on all the pieces when it was assembled) the edges flat to give you 16 sides, then sand round. because the cedar and paulownia is fairly soft, it's fairly easy to sand the octagonal shape round. because of the length it takes a bit of time. you could save some time by using a random orbital sander. make sure you are wearing a mask for this. :safety glasses you can then finish off hand sanding with a sheet of 120 grit to remove any gouges that might show up under the glass.

if you wanted an oval rather than round shaft, like the grey owl paddle, use two strips wider than the other 6, with 3 same length strips, then a wider strip, 3 same length strips and close of with the second wider strip. i did this with my single paddles using 6 x 13mm strips and 2 x 15mm strips. i'd recommend thinning them down a bit more and use 5mm thick strips. since it's glassed you could probably use 4mm.

as far as the drip rings go, i'm not worried about the water dripping from the blades so much, it's more the water that wicks down the shaft, onto your hand, down your arm and into your armpits :laughing

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Cruiser
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Re: low angle double paddle build

Post by Cruiser » Sat Oct 25, 2014 8:27 am

Thanks for the sanding info, I am planning on trying my paddles without glassing, I've read in a few places that it shouldn't be required ... but that is another project.

If you get water down your arm, you are trying to use that paddle with a kayak stroke, I haven't really thought about how high I get the end of the paddle, but I know it is so low that any water only drips into the boat. Certainly, it shouldn't come any where close to wetting your arm. The stroke is just too low of an angle for that .... I think you have created something that will work really well. Nice thing is it is not readily available anywhere and is suited to the canoe.



Brian

Rabbit
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Re: low angle double paddle build

Post by Rabbit » Wed Mar 25, 2015 2:12 am

i had originally planned on posting this once i had a chance to try it out, but i got diagnosed with a hernia, so i had to stop taking the canoe out. then i had surgery, and now i have to wait for some time to recover before i'll be able to lift the canoe on and off the car...

not being entirely happy with the parachord drip rings, i decided to make some wooden ones. i wanted something that would catch the water rather than just redirect it, so i went with a more cupped design.

i don't have a wood turning lathe, so i cut out some disks from 9mmm ply using some hole saws. i cut 3 disks and glued them together, then smoothed the inside with a drum sanding attachment on a dremmel and the outside with a disk sander.

the first disk was cut using a 70mm hole saw to cut the outside diameter and a 51mm hole saw to cut the inside diameter. the second disk was cut using a 70mm hole saw to cut the outside diameter and a 44mm hole saw to cut the inside diameter. the third disk was cut using a 51mm hole saw to cut the outside diameter and a 33mm hole saw for the inside diameter. once glued together, sanded with the dremmel and coated with epoxy, they look like this:

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i then split the drip ring with a razor saw and attached it to the shaft with double sided tape usually used for attaching automotive trim. the split line was then sealed with hot stuff ca. on the paddle it looks like this:

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once i'm physically able to get back out on the water again i'll report back on the effectiveness. if nothing else it looks good :laughing

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