Shopsmith Forums

Can you sand the concave underside on the top of your strip sander? I know that it would be cross grain, but you might be able to get to the point where a little hand sanding will finish up.

Mike

Mike, that's a very good suggestion and I will give it a try. Thanks!

Mike907 wrote:Can you sand the concave underside on the top of your strip sander? I know that it would be cross grain, but you might be able to get to the point where a little hand sanding will finish up.

Mike

I don't know anything about this but here is a suggestion. Make an entire cylinder with the birds mouth joint to make it easier to clamp up. Use your finish wood around the circumference only enough to give you enough material to provide the amount for the two decks. use scrap wood for the rest. Once glued up and dry, turn the outside and inside on the lathe to get them smooth. Cut out your finish wood from the cylinder and cut to shape for the canoe ends.

jsburger wrote:I don't know anything about this but here is a suggestion. Make an entire cylinder with the birds mouth joint to make it easier to clamp up. Use your finish wood around the circumference only enough to give you enough material to provide the amount for the two decks. use scrap wood for the rest. Once glued up and dry, turn the outside and inside on the lathe to get them smooth. Cut out your finish wood from the cylinder and cut to shape for the canoe ends.

jsburger, that's ingenious! But the diameter or the cylinder I used for these decks was 20 inches, which exceeds the 16 inch swing of the Shopsmith. I think an arc (or chord) off of a 16 inch diameter cylinder is going to have too much camber for these decks.

Algale, is the end grain of the curved deck glue-up going to be visible on the finished canoe?

BuckeyeDennis wrote:Algale, is the end grain of the curved deck glue-up going to be visible on the finished canoe?

Yes, and that's an issue I have thought about. May add a piece across the end grain to hide it.

algale wrote:

jsburger wrote:I don't know anything about this but here is a suggestion. Make an entire cylinder with the birds mouth joint to make it easier to clamp up. Use your finish wood around the circumference only enough to give you enough material to provide the amount for the two decks. use scrap wood for the rest. Once glued up and dry, turn the outside and inside on the lathe to get them smooth. Cut out your finish wood from the cylinder and cut to shape for the canoe ends.

jsburger, that's ingenious! But the diameter or the cylinder I used for these decks was 20 inches, which exceeds the 16 inch swing of the Shopsmith. I think an arc (or chord) off of a 16 inch diameter cylinder is going to have too much camber for these decks.

Argh! Didn't think of that. However, 16" really is not that smaller a radius given the application. Turn it that size and see how it looks. Thinking about it, I think you are right in that it may not look right but it might be worth a try. Your discerning eye is what counts and so far it looks like you are right on.

It might be worth exploring an adapter to turn off the end of the SS to do larger diameters. Since you have spent so much time on this project you don't want to compromise at the end.

I have stories about hunting and canoeing in Quebec Canada back in the 80's that I will never forget. A 16' Ceder strip and canvas canoe with a portage yoke. Just beautiful. I shot a Moose from that canoe with my fathers WW II captured German 9 MM Mouser rifle that had the stock sporterised by my Grandfather.

I also think that the converging grain pattern from your experiment #1 is much prettier. If you can hide the end grain, I'm thinking that you can get exactly the look you are wanting, without excessive sanding and shaping. First, glue up the deck with the grain pattern that you like, but glue it up flat. Then form the curve by "kerfing" the deck. Here's the general idea:
How to Master the Radial Saw, by Wally Kunkel (pp 63-65), has some very good info on this technique, including how to determine the kerf spacing to get the curvature that you desire. Done properly, the kerfs close completely at the desired radius of curvature. Fill them with glue, and you have a very strong structure. You could also use your end-grain-hiding piece to control the radius and reinforce the structure.

Here's a YouTube video that illustrates the kerfing concept.

[youtube]https://www.youtube.com/watch?v=g49H35ie2eQ[/youtube]

In both the book and the video, the "veneer" section (i.e. the thin layer of wood that is not kerfed through) is cross-grain to the kerfs. If it were parallel, I fear that the it might be too weak, and crack along the grain. For your deck, I'm thinking that the diagonal grain from the "converging" design should be sufficiently strong. Once epoxied (and especially if fiberglassed), it should be bulletproof.

jsburger wrote:

algale wrote:

jsburger wrote:I don't know anything about this but here is a suggestion. Make an entire cylinder with the birds mouth joint to make it easier to clamp up. Use your finish wood around the circumference only enough to give you enough material to provide the amount for the two decks. use scrap wood for the rest. Once glued up and dry, turn the outside and inside on the lathe to get them smooth. Cut out your finish wood from the cylinder and cut to shape for the canoe ends.

jsburger, that's ingenious! But the diameter or the cylinder I used for these decks was 20 inches, which exceeds the 16 inch swing of the Shopsmith. I think an arc (or chord) off of a 16 inch diameter cylinder is going to have too much camber for these decks.

Argh! Didn't think of that. However, 16" really is not that smaller a radius given the application. Turn it that size and see how it looks. Thinking about it, I think you are right in that it may not look right but it might be worth a try. Your discerning eye is what counts and so far it looks like you are right on.

It might be worth exploring an adapter to turn off the end of the SS to do larger diameters. Since you have spent so much time on this project you don't want to compromise at the end.

I have stories about hunting and canoeing in Quebec Canada back in the 80's that I will never forget. A 16' Ceder strip and canvas canoe with a portage yoke. Just beautiful. I shot a Moose from that canoe with my fathers WW II captured German 9 MM Mouser rifle that had the stock sporterised by my Grandfather.

What great memories those must be!

BuckeyeDennis wrote:I also think that the converging grain pattern from your experiment #1 is much prettier. If you can hide the end grain, I'm thinking that you can get exactly the look you are wanting, without excessive sanding and shaping. First, glue up the deck with the grain pattern that you like, but glue it up flat. Then form the curve by "kerfing" the deck. Here's the general idea:

Kerfing.JPG

How to Master the Radial Saw, by Wally Kunkel (pp 63-65), has some very good info on this technique, including how to determine the kerf spacing to get the curvature that you desire. Done properly, the kerfs close completely at the desired radius of curvature. Fill them with glue, and you have a very strong structure. You could also use your end-grain-hiding piece to control the radius and reinforce the structure.

Here's a YouTube video that illustrates the kerfing concept.

[youtube]https://www.youtube.com/watch?v=g49H35ie2eQ[/youtube]

In both the book and the video, the "veneer" section (i.e. the thin layer of wood that is not kerfed through) is cross-grain to the kerfs. If it were parallel, I fear that the it might be too weak, and crack along the grain. For your deck, I'm thinking that the diagonal grain from the "converging" design should be sufficiently strong. Once epoxied (and especially if fiberglassed), it should be bulletproof.

That's an interesting idea (and another technique I've read about but never tried). I think you identified the big question: whether the piece will crack at the kerfs with the grain running diagonal. Another experiment may be in order.