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Bezier 12.5
Transverse Frame Construction
TRANSVERSE FRAME ASSEMBLY METHOD
We will be using a corner-to-corner measurement method to fabricate the frames, therefore four (4) dimensioned drawings are provided for each frame. The upper left drawing gives horizontal dimensions, the upper right vertical dimensions, the lower left angled dimensions and the lower right degree angle dimensions. These drawings are scaled at 3/4" = 1'0", therefore any other dimension required by you can be read using an architect scale ruler.
To describe this method we are going to cut, on paper, a rectangle 10" x 20". The question is how do we know if this 10" x 20" piece is really square (all corners 90 degrees) without the use of a framing square?
The answer is to measure corner to corner with a tape measure. Both measurements from the corner to opposite diagonal corner must be the same to be square. If they are not you have a parallelogram not a rectangle.
The sketch below shows two rectangles. Both have sides which measure 10" x 20". The top rectangle has perfect 90 degree corners, therefore its diagonal dimension corner to corner are equal. Both corner to corner measures 22.361".
The bottom rectangle (Really a parallelogram) is out of square by 2.5 degrees. Its corners have angles other than 90 degrees. Its diagonal dimensions are different. The corner-to-corner here are 22.749" for the large dimension and 21.967" for the smaller dimension.
To bring the parallelogram back to the desired shape, subtract the smaller dimension from the larger, then divide by two. This number would either be added to the smaller dimension or subtracted from the larger dimension. This would bring us back to the correct, square diagonal dimension of 22.361"
This method holds true for irregular shapes, such as transverse boat frames as it does to a simple square or rectangle.
Use small tack welds to hold the parts in position as you measure back and forth at all locations. The angled dimensions will verify the horizontal and vertical dimensions and vice versa. Only when all dimensions are held everywhere will the frame to true.
If you need to break a tack weld and adjust by grinding off a hight spot do so. If the frame does not square up dimensionally at any location, look for the reason, such as a part being to long or short, a notch being cut to deep or not deep enough or a high spot or low spot.
Another cross check is to measure from a longitudinal notch on one side of the centerline to a different longitudinal notch on the other side. It must match the reversed location.
Headstock Line
The headstock angle 2" x 2" x 1/4" angle is the last member to be added after the frame has been dimensionally squared. The angle is used to setup the frames of the building strongback. The headstock angle is dimensioned from two different locations as shown on the drawings. See next chapter on the "Building Strongback" and "Setting Up".
Finally add any stiffeners and supports out of scrap material to hold the frames in shape while moving and setting up. See above drawing.
Again only when all dimensions are held everywhere will the frame be true.
