10-28-2009, 01:14 PM
Success!
First, THANK YOU MATT AMT! Last night, in the last moments before putting the rawhide on, I went back and re-read Matt's website (and what a great website it is) and accepted his warning that rawhide shrinks and has enormous power when shrinking at face value.
Second, I believe that I was right six months ago when I claimed that the "cut-outs" were there because of the way rawhide behaves when shrinking. In a nutshell, heavy rawhide doesn't shrink at a uniform rate across the hide--the thinner "belly" shrinks at a very different rate from the thicker shoulders. By placing a torsioner int he "cut out" that allows the rawhide to be tightened along a radius instead of trying to get it "out to the side" on an oval, you can have a deeply dished convex surface on your Boeotian and still stretch the rawhide tight.
There's another factor/artifact of the creation process. On Matt's website, you can see one of his shields bent under the strain of rawhide contraction. The WHOLE POINT of the Boeotian shape (as I suspected) is to crate a frame that resists that shrinkage. If that frame had long sides (an oval) one or both of them could easily collapse inward under the pressure of the rawhide--snapping the rim or simply distorting the finished product. I suspect that a perfectly good oval shield could be built by decking over the cut-outs (as I did initially) and leaving the torsioners there as braces--but the belly of the rawhide would then have no place to be "collected" as it shrank, and so there'd be bumps in the surface--OR the oval would have to be flatter and less convex.
My first boat hull is 95% dry and solid as a rock. I am worried that the last 05% of drying may warp the frame, but I don't THINK so. Weight is heavier than I'd like--it is 9 pounds now and hasn't got a porpax or antelabe. But I don't think I could get ANYTHING through the face of it. Not on the first try, anyway!
Now some pics. This is the rawhide over the shield. Luckily, when I was getting ready to tear my hair out, I remembered that I had another set of bent wood "rims" and I used them as "clamps" as I fitted and cut the hide.
![[Image: 11862_187336221203_681611203_3807318_1400125_n.jpg]](http://photos-c.ak.fbcdn.net/hphotos-ak-snc1/hs011.snc3/11862_187336221203_681611203_3807318_1400125_n.jpg)
See how the hide already wants to buckle at the "cut outs". Nothing to do with the actual cut out--but cutting the leather here relived most of the strain!
![[Image: 11862_187336226203_681611203_3807319_7797832_n.jpg]](http://photos-e.ak.fbcdn.net/hphotos-ak-snc1/hs011.snc3/11862_187336226203_681611203_3807319_7797832_n.jpg)
ready to start cutting holes and lacing.
![[Image: 11862_187336241203_681611203_3807320_3333765_n.jpg]](http://photos-d.ak.fbcdn.net/hphotos-ak-snc1/hs031.snc3/11862_187336241203_681611203_3807320_3333765_n.jpg)
First, THANK YOU MATT AMT! Last night, in the last moments before putting the rawhide on, I went back and re-read Matt's website (and what a great website it is) and accepted his warning that rawhide shrinks and has enormous power when shrinking at face value.
Second, I believe that I was right six months ago when I claimed that the "cut-outs" were there because of the way rawhide behaves when shrinking. In a nutshell, heavy rawhide doesn't shrink at a uniform rate across the hide--the thinner "belly" shrinks at a very different rate from the thicker shoulders. By placing a torsioner int he "cut out" that allows the rawhide to be tightened along a radius instead of trying to get it "out to the side" on an oval, you can have a deeply dished convex surface on your Boeotian and still stretch the rawhide tight.
There's another factor/artifact of the creation process. On Matt's website, you can see one of his shields bent under the strain of rawhide contraction. The WHOLE POINT of the Boeotian shape (as I suspected) is to crate a frame that resists that shrinkage. If that frame had long sides (an oval) one or both of them could easily collapse inward under the pressure of the rawhide--snapping the rim or simply distorting the finished product. I suspect that a perfectly good oval shield could be built by decking over the cut-outs (as I did initially) and leaving the torsioners there as braces--but the belly of the rawhide would then have no place to be "collected" as it shrank, and so there'd be bumps in the surface--OR the oval would have to be flatter and less convex.
My first boat hull is 95% dry and solid as a rock. I am worried that the last 05% of drying may warp the frame, but I don't THINK so. Weight is heavier than I'd like--it is 9 pounds now and hasn't got a porpax or antelabe. But I don't think I could get ANYTHING through the face of it. Not on the first try, anyway!
Now some pics. This is the rawhide over the shield. Luckily, when I was getting ready to tear my hair out, I remembered that I had another set of bent wood "rims" and I used them as "clamps" as I fitted and cut the hide.
See how the hide already wants to buckle at the "cut outs". Nothing to do with the actual cut out--but cutting the leather here relived most of the strain!
ready to start cutting holes and lacing.
Qui plus fait, miex vault.
