coves too deep??

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tptbum
Posts: 29
Joined: Sat Jun 09, 2007 9:17 am
Location: Ann Arbor, MI area

coves too deep??

Post by tptbum »

Hi all,

after my first three courses of strips I realized that the coves that I routed in my strips are slightly deeper than the beads are tall. This results in a little (really tiny) air space at the bottom of the cove.

I am thinking this is not good for two reasons - if the bead does not "bottom out" the glue joint wont' be as strong - more scary - if I get over excited in the sanding process there is a chance I could sand through the walls of the cove and have holes between the strips!

Today I tried two techniques - sanding and planing. The edges of the coves are so paper thin it does not take much effort to sand a hair off of them - takes time, but not much effort. When I used the plan - set really thin, my result was less consistant, there are places I think I took off too much.

I guess what I am after is "how deep should your coves be relative to your beads?" Is it important that the strips bottom out - Is a really shallow cove best?

I realize that as I start turning the bilge it becomes even more important, as the strips will now be going in at sharper angles to each other. I have a few more courses to practice on before I get there.

John
David James
Posts: 223
Joined: Tue May 11, 2004 9:04 pm
Location: Glenview, Illinois

Post by David James »

John, for an excellent description on how to mill perfect strips see John Michne's web site: http://www.michneboat.com/Making%20Strips.htm
I have found his instructions and illustrations very helpful.

Personally, I want my strips to bottom out. On my recent build, a Rob Roy, I milled my strips to .200" and used a 1/8" radius bit. At this thickness the cove was never too deep. After having routed the bead, the cove routing then provided a consistent overall strip width as a bonus. Anyway, it worked for me. No gaps after sanding.

As to your question of how deep the coves should be, you want the resulting edges to have some thickness to them (John Michne recommends .010"). This part of the strip will be sanded away later anyway.

Good luck, Dave
"If given six hours to chop down a tree, spend the first four sharpening your ax." - Abraham Lincoln
BearLeeAlive
Posts: 196
Joined: Tue Aug 18, 2009 7:00 pm

Post by BearLeeAlive »

Would it not be more of a matter that the beads were not cut to full depth? I assume there is a pronounced flat spot on the top of the bead. Unless this is really prominent, I doubt there will be an issue with the bonding of the strips. A glue with good filing properties like Lee Valley 2002 would likely fill the gap. Do you have any photo closeups of your strips?

What I did with the test strips was to blacken the edge with a felt marker (a pencil would work too) and adjusted the depth of the bead until just a wee bit of the existing surface remained.

When cutting the coves I left a very slight bit of the edge uncut, less that 1/64, but enough that it was not razor sharp. The main reason was to leave them a bit tougher than bringing them to a razor sharp edge.

They fit real nice together with only the slightest bit of a groove (again less than 1/64) between strips. Just a light sanding and that will quickly disappear.

I do have to add that I am new to strip building canoes, and am building my first, but I am not new to woodworking at all. So i do not speak with lots of directly related experience. I still have a few things to figure out about canoe building.
-JIM-
tptbum
Posts: 29
Joined: Sat Jun 09, 2007 9:17 am
Location: Ann Arbor, MI area

my deep coves

Post by tptbum »

I think the beaded ends are cut to full depth, they are nicely rounded at the top with no flat spots. some of them do have "shoulders" because the strips were cut to imprecise thicknesses.

I am working with poor tools and even poorer skills -
Not sure what made me think that I could build a boat - but I am having fun trying!

I was going to go out and drop $300 on a thickness planer to clean the strips up, but I decided that the only thing it would save me is hours and hours of sanding - maybe it would have cleaned up the router work as well.

In the meantime I have decided that a couple passes with a plane before gluing the strips up seems to make them fit better - I'm really not sure if it is necessary, but I figure the additional advantage is that when I get to the rounding the bilge I can angle my plane a little. The process seems to add about half an hour to the time it takes for me to glue up a mating pair of strips.

Perhaps I will send a pic of my strips, but I am not sure what can be done at this point other than to learn from my experience and keep going forward.

Thanks for the advice

John
BearLeeAlive
Posts: 196
Joined: Tue Aug 18, 2009 7:00 pm

Post by BearLeeAlive »

Having fun and learning is what any kind of woodworking is all about. I am learning lots particular to canoe building, though have done plenty of other types of woodworking.


You don't have to use a planer, though they certainly can help. If you use the smoothest side down on every strip you rout, both for the bead and the cove, then join them with that smooth/down side against the moulds, the stripping will go well. You will have the smooth side of the strip against the smooth mould, and the bead and cove should reference each other well and fit good. The inside of the hulk will require little more sanding than if using planed strips, but the outside, where all the variance in thickness is taken up, will require more sanding to fair the hull. At least the outside would be easier to sand. :smile
-JIM-
CatFaber
Posts: 20
Joined: Wed Nov 03, 2010 4:55 pm

Post by CatFaber »

You're probably okay.

If you end up with gaps between strips after fairing the outside, it's pretty easy to fill them with putty or dookie schmutz (epoxy + sawdust + cab-o-sil.) The unfaired parts on the inside where the strips still touch should hold it all together during this process. When you put the epoxy on the outside, it will fill any holes you miss.

Then you take it off the forms and smooth out the inside--and at this point the strips might have come apart in places except the fiberglass on the outside will bind everything together.

So really, it should be fine.

And epoxy mixed with some of the sawdust (save some of the sawdust from fairing the outside--I like to save a couple of quarts by knocking the sawdust out of the sander's collection bag into a clean dry tub that once held cottage cheese or yogurt) will be a little bit darker than the wood the sawdust came from, which is just what you want for putty--putty darker than the wood is less noticeable; putty lighter than the wood tends to "stick out" visually.
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