cutting the shear

Welcome to the new Bear Mountain Builders Forum - an interactive internet service we provide to encourage communication between canoe and kayak builders
Post Reply
Stargzr57
Posts: 62
Joined: Mon Aug 14, 2006 7:33 pm
Location: Green Bay Wi.
Contact:

cutting the shear

Post by Stargzr57 »

Hello all, I just finnished stripping my Bob's special, and she's looking nice so far. I was wondering when I should cut the shear on the bow and stern. The book that came with the plans says to cut it with a chisel while on the forms. Seems to me it might be eayser to wait intil its glassed and turned over off the forms then I could use my sabre saw with a fine blade to cut it. Anyone have any advice/ thoughts?

Thanks to all ! Steve W.
User avatar
Glen Smith
Posts: 3719
Joined: Sat May 08, 2004 9:08 am
Location: Baie-St-Paul, Quebec, Canada

Post by Glen Smith »

Actually, the forms are used as a reference to know where to cut the sheer-line. That is why Ted recommends doing it while the hull is still on the forms. His chisel method works very well but remember to cut from the ends toward the center so you don't split strips along the grain which will happen if you go the wrong way.

I am sure some builders use a different method that they find easy and perhaps they will respond to your message also.
User avatar
Patricks Dad
Posts: 1476
Joined: Wed Oct 13, 2004 1:11 pm
Location: Warrenville, Illinois

Post by Patricks Dad »

I use a small (~1" diameter) circular saw blade on my dremel tool to cut the sheerline as well as the centerline (just finished that this afternoon). This saw cuts a straight line fairly well but struggles a bit on curves (previous canoe was a Redbird which has a failry curved sheerline).

Edit: I cut the sheerline before glassing while the canoe is still on the forms....
Randy Pfeifer
(847) 341-0618
Randy.Pfeifer1@gmail.com
Markham_David
Posts: 47
Joined: Sat Feb 26, 2005 2:12 pm
Location: Markham, Ontario

Post by Markham_David »

Steve, I had success with a1/2" Olfa knife, before glassing. I transferred the reference marks from the forms to the outside of the hull, then used a batten and a fine marker (Sharpie) to define the sheer-line. The same caveat applies as with a chisel: cut from the ends to the centre, and score the line deeper with several light cuts from a new blade. Subsequent cuts can be heavier without much danger of veering off the line.

Whatever method you choose, good luck!

David
User avatar
Adamv
Posts: 109
Joined: Fri Mar 04, 2005 1:40 pm
Location: Owen Sound, ON Canada

Post by Adamv »

Hi Steve,

I used this circular saw blade for my Dremel tool to cut the sheer on my Bob's Special. It worked very well, and as Patrick's Dad says, it cuts quite straight. Remember to cut at least an 1/8" off the sheer line so you can trim down to it flush with the gunwales when you put them on.

http://www.amazon.com/Dremel-670-01-Min ... B00008Z9ZP

I also found this tool to be very helpful for cutting the strips to fit in the second half of the football.

Adam
Who travels not by water knows not the fear of God --- 17th Century Sailor
User avatar
davidb54321
Posts: 214
Joined: Fri Jan 28, 2005 7:05 pm
Location: Presque Isle, Maine
Contact:

Post by davidb54321 »

Steve,

A utility knife works very well. Like has been said, make your cut proud of the mark so you can plane it even with the gunwales later on.

Cut from end to middle.
David Bartlett

"I don't fully understand everything I know!"
http://photobucket.com/albums/b81/davidb54321/
McFLY
Posts: 11
Joined: Sun Jul 05, 2009 12:12 pm
Location: Indianapolis, IN, USA

What about a router for cutting the sheer line?

Post by McFLY »

I've finally finished planking the hull and it's time to cut the sheer line. I've transferred the sheer line marks from the stations to the outside of the hull a-la CanoeCraft. While I didn't have too much trouble trimming to the center line with a chisel and block plane, I can't get the idea of using my router out of my head.

Here's what I'm thinking: what if I hot glue a strip a little proud of the marks and use a flush trim bit in the router to trim the hull flush with the batten? (Flush trim bits have a bearing between the router bit and the motor that rides flush with the cutting edge.) I've seen a few posts where people have used a Dremmel, but have any of you given a router a shot? I haven't tried hot glue for anything else on this project. Do you think it'll hold? I'm using staples to hold the strips to the molds, but I'd kind of like to avoid more staple holes in random spots.

My hull is still on the molds, and I did not bend the first strip to follow the sheer, for what it's worth.

So, what do you think?

Thanks,

Brian
User avatar
Adamv
Posts: 109
Joined: Fri Mar 04, 2005 1:40 pm
Location: Owen Sound, ON Canada

Post by Adamv »

Brian

I can't comment on the effectiveness of using the router for this task per se, but I would add a couple of thoughts. First, I wouldn't worry about stapling the guide batton on, because it will be more or less at the same spot as the gunnels will be, and thus, any staple holes will be covered by them. Second, will you set your router depth so that it will not cut through your station moulds, or, just let it cut through them? And third, perhaps you could fix a small piece of plank to the base of the router to keep the router parallel to the hull during the cut.

Let us know how it works.

Cheers
Adam
Who travels not by water knows not the fear of God --- 17th Century Sailor
McFLY
Posts: 11
Joined: Sun Jul 05, 2009 12:12 pm
Location: Indianapolis, IN, USA

Post by McFLY »

Thanks for the tips, Adam!

I was planning on cutting through the station molds (very slowly) because I didn't see a reason for cutting out the weird keyhole shapes on the fore and aft stations when I originally cut the molds in December. The plans for the Freedom 15' have the molds shaped such that most of them end at the sheer line, making the mold a mushroom shape. Like I said, the molds fore and aft, where the canoe is about the same width or narrower than the strongback at the sheer line, have small cut-outs specified at the sheer line. Now I know why!

Great point about the staple holes being covered by the gunnels. I'll save the hot glue for attaching a strip to my router base. Hopefully I'll get to it tonight or Friday! I'll keep you posted.

-Brian
User avatar
Patricks Dad
Posts: 1476
Joined: Wed Oct 13, 2004 1:11 pm
Location: Warrenville, Illinois

Post by Patricks Dad »

Before you start make sure your molds are high enough above the strongback so that the strongback won't interfere with the router near the bow and stern. I don't think it would have worked for me (I didn't raise my molds above the strongback any higher than the original plans and I think my router would have hit the strongback on this sort of operation). You might be just fine with your set-up however.

Just a thought.
Randy Pfeifer
(847) 341-0618
Randy.Pfeifer1@gmail.com
sedges
Posts: 325
Joined: Fri Jul 09, 2004 5:37 pm
Location: georgia

a contrary point of view

Post by sedges »

I may be the only one that does this, but thought I'd throw it in the mix.

I really like to determine the sheer line with the boat upright. Maybe its just that I have a hard time "seeing" the line when it is upside down and in a cramped space.

I pull it off the molds uncut and set it in cradles out on the lawn. I take a planed outwale stock and clamp it on with spring clamps. Not too many either. I like to have the gunnel take the sweep the way the wood bends and not force it into shape.

After I look at it for a day or so, trying little adjustments, I will clamp it with heavier clamps and scribe a line. Then I measure at each station, easy because I still use staples, from the keel line to the scribe and mark the other side. When all marks are made I clamp another gunnel to the marks and scribe the line. I then make a rough cut above that line with a sabre saw.

This may not work if you don't have those nice rows of staple marks showing the stations.
Tim Eastman
Posts: 245
Joined: Sun Oct 23, 2005 12:40 pm
Location: Grand Rapids, Michigan, U.S.A.

Post by Tim Eastman »

McFly I am also building a Freedom and have molds similar to yours. I am intrigued by your proposition. I think it is doable. I would still cut it proud of the shear line and still plane down to it when the gunnels are in place.

If you do a test and you drop dead nail it with confidence then go to the line. But my router skills are legendary. I can make expensive kindling out of anything on the boat. :laughing

If you have success with it take some before and after pics for your setup.
Tim Eastman
~~~~~~~~~~~~~~~~~~~
Be an example worth following
User avatar
frugal
Posts: 66
Joined: Tue Jan 22, 2008 12:54 pm
Location: Oshawa, ON

Post by frugal »

I think you guys are really overthinking things and making stuff way too complicated.

I wouldn't glue a strip so that I could use a router. I'd be more concerned that I'd bugger up the wood when I removed the glued strip. I'd also be concerned about the potential damage to router bit could do if I slipped.

I never found it difficult to mark the shear using a batten, cutting close (within 1/4 inch) with a saw and using a chisel and/or a surform to take the material down to the pencil mark. You can even do this step such that you only bring it close to the line right now. Once you glass the outside and flip it right side up you can finish the job before you glass the inside.

I'm assuming that you're making this canoe for yourself. Let the job take as long as it takes. Enjoy the experience and don't rush through it. Make sure your tools are sharp and take shallow cuts. You'll find it's easier than you think.
James Hanrahan
Posts: 23
Joined: Thu Sep 13, 2007 6:48 pm
Location: Wiarton Ontario

Post by James Hanrahan »

I just marked the sheer line locations on the inside of the hull with an awl at each form before I removed them(you could also put them back in temporarily and mark them). I then glassed and did all epoxy coatings. After completion I just clamped a long straight batten (gunwale or strip) to align the marks with the canoe right side up and used a utility knife to lightly score the line. Then after removing the batten I continued to score through the epoxy and glass. After a couple of runs each time slightly deeper it cut right through creating an even sheer line which I then just ran a long sanding blok over to create a perfectly fair and even edge. This has taken longer to type than it did to cut the sheer line. I couldn't see spending the time to set up a router for such a task
James
McFLY
Posts: 11
Joined: Sun Jul 05, 2009 12:12 pm
Location: Indianapolis, IN, USA

Post by McFLY »

It's been a while since I logged in, but I thought I'd update this thread for those interested.

I got my shear lines all cut, using a combination of methods from above. I figured I'd try several to see how they did.

I stapled a batten along the shear line and used a flush trim bit in my router to cut most of it. It went very quickly and wasn't too awkward holding the router against the hull. The strip I was using as a batten did get too thin at one point and the bearing slipped off. It took a nibble out of the hull, but I'll be able to clean it up when I put on the gunwales. The bit had no problem going through the plywood stations where I forgot to cut a relief at the shear line.

It did get tight using the router near the stems, so I switched methods for those spots. I tried using a sharp chisel to split the excess wood off like is done when cutting the centerline. I also tried using a utility knife to cut the sheer line. The utility knive came out a little cleaner, but I had to change the blade after a couple feet. It took about 5 passes to cut through the cedar. The chisel went faster. You certainly need to pay attention to the book and work in the right direction using the chisel.

Overall, I'm glad I used the router. It went very quickly, I didn't have to stop to sharpen things, and the cuts came out cleanly. Using hand tools to do the tighter spots at the bow and stern was great, but I'm glad I didn't have to do it over the entire length of the boat.

I've glassed the outside and popped it off the mold. Now it's on to shaping the inside.
Post Reply