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View Full Version : making patterns for stern braces/knees.



davebrown
04-13-2009, 02:16 PM
five yrs ago i was up in the sierras and came across a big doug fir root that was exposed on a bank, with about the right angle for side stern braces (stern knees? not sure of the exact proper term here--where the inside braces parallel the gunnel on one edge and attach to the inside stern on the other, at shear). so i brought a big piece home, planed it somewhat square, painted the ends and let it sit until saturday, at which time i set about splitting it and then making apattern for my braces. i used luann ply and superglued triangles to create a series of points, which i then transferred to the blank.

long story short, i had pretty good luck cutting out my braces to my pattern, but my pattern was poorly executed. luckily, i did not ruin this knee, and they are good enough, with a bead of epoxy to make up for my inexperience, but i am wondering how the pros cut patterns for these parts? i saw some rossel cut on (i believe) a susan skiff out on the SF pier three or four yrs ago, and his were damned exact. mine have about an 1/8" plus or minus on most points. i spent a half a day on them, but worse, i was constantly worried about how i wasn't going to go to home depot and replace this air-dried root...comments and photos are appreciated.

davebrown
04-14-2009, 12:48 AM
great stuff. thnx. i got my braces installed--they are clumsy, but the grain is beautiful. my fittings are secure but ugly. overall, i am satisfied--i didn't ruin my blanks, and my fitment was good enough to be a strong joint, and probably only to the pros will it be apparent how far out they are. but my next boat is the mythical shearwater 18, so i have to step it up a notch to be worthy...if i can figure out the photo process, i will post. the pros will get a laugh, and the amateurs will be inspired to think, Hey i can do that...as an aside, my figured black walnut that i am using for the breasthook is stunning. i got it and my stern braces installed tonight.

davebrown
04-14-2009, 12:52 AM
if i didn't say so, bhofm--you went to all that trouble, very informative. thnx again.

S B
04-14-2009, 11:13 PM
five yrs ago i was up in the sierras and came across a big doug fir root that was exposed on a bank, with about the right angle for side stern braces (stern knees? not sure of the exact proper term here--where the inside braces parallel the gunnel on one edge and attach to the inside stern on the other, at shear). so i brought a big piece home, planed it somewhat square, painted the ends and let it sit until saturday, at which time i set about splitting it and then making apattern for my braces. i used luann ply and superglued triangles to create a series of points, which i then transferred to the blank.

long story short, i had pretty good luck cutting out my braces to my pattern, but my pattern was poorly executed. luckily, i did not ruin this knee, and they are good enough, with a bead of epoxy to make up for my inexperience, but i am wondering how the pros cut patterns for these parts? i saw some rossel cut on (i believe) a susan skiff out on the SF pier three or four yrs ago, and his were damned exact. mine have about an 1/8" plus or minus on most points. i spent a half a day on them, but worse, i was constantly worried about how i wasn't going to go to home depot and replace this air-dried root...comments and photos are appreciated.
We call em quarter knees, they are easily cut before the planking goes on. Measure the angle, the sheer meets the stern and cut one arm to fit. Secure the knee in place and run a batten above and below the knee where it would meet the plank. Scribe the knee and cut to the line. Then shape the remainder. It can be left in place or removed for later. There is a procedure for fitting them after the plank is on but I don't think my typing finger will last that long.

davebrown
04-15-2009, 12:04 AM
of course! makes perfect sense to take these shapes before the sides are planked. i did it backwards. they aren't too bad, but on the next one, i want them to be right.

S B
04-15-2009, 06:31 PM
of course! makes perfect sense to take these shapes before the sides are planked. i did it backwards. they aren't too bad, but on the next one, i want them to be right.
I thought about it after and I should have at least given it a try. To make a pattern for a knee scribe lines on the boat where the knee will fit, top and bottom. From thin board, cut a piece roughly matching the bottom, within 1/2" is good. Tack in place with it's top edge in plane with the bottom line ,matching both plank and stern. Tape a piece of paper on top. Now cut a small square from stock the same thickness as the finished knee. Bevel two adjacent edges forming a point. Lay the block big side down on the paper, place the point at locations needing to be recorded and scribe position, of block, on paper, at the other end. repeat for as many points as needed. Then turn the block over, big side up, and repeat procedure, this will give you the top of the knee. Good idea to use different colour pencil. Remove paper and tape to larger piece. Using the marks on the paper reposition the block and reverse your actions, leaving the block big side down for top and bottom. Connect the dots to form pattern. Good luck.

Thad Van Gilder
04-16-2009, 06:56 AM
I use luane for patterns. on a quarter knee or stern knee, I'd make the patter for the bottom of the knee and pick up the bevels on top of it, and make the bevels on the pattern.

works well and is easy.

if you need a pattern for the pattern, which I sometimes do, I use cardboard.

-Thad

davebrown
04-16-2009, 10:32 AM
i used luann with heavy craft paper superglued to form a series of transferable points. i think my error was to take the TOP of the quarter knee, and estimate the bevel on my bandsaw. i will try to post a photo today. it's not the worst joint i have ever cut, but far below the professional level.

davebrown
04-16-2009, 02:40 PM
walnut breasthook, with figure. discoloration is simply epoxy that was excess and brushed off.

http://www.flickr.com/photos/37481714@N04/3448427300/

quarter knee, port:

http://www.flickr.com/photos/37481714@N04/3447612483/in/photostream/

quarter knee: starboard:

http://www.flickr.com/photos/37481714@N04/3448426954/in/photostream/

i still can't get photos to download on this here site.