February 9, 2007

Tonight I cleaned up the shop a bit and started a new rib. I got a pounce wheel to make it easier to transfer the full size rib pattern to the plywood back board. I just follow the rib line with the little wheel with the plywood underneath and the markings get transferred right through. The damage to the blueprint is minimal. I still had to be careful not to wander off the line but I made sure I had the line marked the whole way and it was easy to tell when I was drawing through the marks later, which markings not to use. Do an internet search to see a better picture but this one gives a good scale to see how small it is.

I found it much easier to draw the curves accurately with the pounce wheel markings. I still punched tiny holes for the reference line and used a ruler to draw it in later. I guess I could have used the ruler with the pounce wheel but it seemed easier to just draw the line with a pencil. Next, I measured and drew in all the uprights and diagonals.

I also pre-bent the capstrips for this rib. Again, I used the pounce wheel to transfer the upper rib line to the 2x4 and then drew the line down a little further to account for springback. I may have overdone the overbend a little but as long as the capstrip bends in the mold without breaking, I can usually unbend it a little by hand with I load it in the jig.

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