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Permalink Reply by Pat Kelly on October 26, 2017 at 4:46pm

I used a technique I learned in the boat building business. Get some 6d finish nails and a drill the same size as the nails. drill holes for the nails at the intersection points just outside the line. insert the nails in the holes. Find a piece of flexible metal. Old band saw blade, banding material. and bend it around the nails. this should give you a nice curve all around the points. Draw the curve with a pencil along the band and cut out your form. have both blocks screwed together when you cut them so they are identical. Good luck.

Pat

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Permalink Reply by Damon Brantley on October 26, 2017 at 8:18pm

Welcome to the fun world of scratch building! :) I am scratch building a 650. For the 650 plans, there are reference datums defined in the plans for the front and rear ribs. For the rear rib, (0,0) is off the part. For the front rib there should a be a nose radius specified. You would want the graph specifed part to intersect the nose radius at a tangent.

If you have not done so, I would recommend getting a copy of homebuilt helps scratch building basics. I will also point you to a video I made that on youtube  https://www.youtube.com/watch?v=-NUe5m02W5w  that covers some of the layout techniques I developed that you might find useful. Of course there are a ton of others on youtube and on my channel.

Another hint I will add. When you do the layout for the ribs, do not layout directly on the plywood. Do your layout on some .025 or .016. Once you get that right, use it as a template for your plywood form.

Good luck.

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Permalink Reply by Dan Hill on October 27, 2017 at 9:33am

In connecting the datum points a flexible ruler on edge will workfine  or a drafting "gumby" allows you to form a smooth transition all the way around the nose. As long as it is a smooth curve and hits all the points it will be fine. Don't overthink it as lots of people have been able to do this before you. Dan.

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Permalink Reply by Michael T. on October 27, 2017 at 2:12pm

But my favourite thing is to over think it..lol

Ok...the wing nose rib and rear rib look good, but I had an interesting time with the tail tip rib. This rib is symmetrical. I made this drawing 3 times and each time I measured the skin lines with my flex ruler I came up with 3 or 4 mm diffrence side to side.

So I gave up trying to make it symmetrical , went to the dollar store and bought some Bristol board and created a half template that I just flipped over the centre line so I could trace the shape. So even if it's off by a bit it's symmetrically off by a bit.

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Permalink Reply by Ernest Christley on December 20, 2017 at 2:06pm

Make a CAD drawing and take it to Kinko's.  Measure a few points before you leave to make sure they didn't scale it.  Sparingly use spray glue to "wallpaper" the printout onto your plywood.  Small parts can be printed out on a regular laser printer.  Use ledger or legal sized paper to get larger than 8x11.

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