A NEW LOCK DISC
What I thought would take a couple of days turned out to take much more. I decided that I would try to use the most precise method of drilling and cutting the discs, the method of using a drill press and a drill jig with a centering peg, detailed earlier in this thread at:
http://www.quiltingboard.com/vintage...ml#post7259359
The thing that took the time was an effort to improve on the method of cutting the circular disc. I made three separate guides for use with my bench-top bandsaw, the final two of which are shown here. The first went in the trash. The bandsaw simply would not follow the circular path I wanted it to. I'm sad to say I spent a few days experimenting with this.
(Bandsaw Edge Cutting Guides)
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I finally gave up and cut the disc with my hand jigsaw. This is the same way I cut the lock disc for the original prototype workstand. This actually turns out to be easier and simpler. I can get a very good circle. The results are shown below.
(Disc Cut With Jigsaw)
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Drilling
I want the sixteen holes to be equidistant from the center hole, which is the center of rotation. Uniform drilling allows the lock pin to work equally well with all holes. I printed out the lock disc template located earlier in this thread at:
http://www.quiltingboard.com/vintage...ml#post7252380
I considered several ways to get the sixteen radial marks transferred to the wooden disc. I finally decided that the easiest way was to punch the centers with a hole punch. There are already horizontal and vertical lines on the disc from the process of cutting it. I aligned the paper with the pencil marks on the wooden disc at 3, 6, 9 and 12 o'clock, then marked through the hole locations in between. These marks will show me where to position the disk as I drill each hole. The smaller disc is incidental and goes on the opposite side of the workstand for equal spacing of both pivot shaft assemblies.
(Lock Disc Printout)
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I made a jig from a block of wood, with a peg for the disc to turn on. The block is clamped at the back to the bed of the drill press and cannot move. The loose piece of scrap wood under the drill bit can be moved around to offer a fresh spot to drill into, for each successive hole. Drilling into a piece of wood underneath minimizes back side splintering around the hole. The basic setup (without disc) is shown below.
(Drill Press Setup)
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The disc is placed over the peg, ready for drilling.
(Disc Ready For Drilling)
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I stopped part way around the disc to take this picture.
(Disc With Holes Drilled)
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The completed disc is shown below. It has been drilled and pegged with a pin to lock the disc to the perforated tubing upright. The peg is new. I believe it is an improvement over the previous lock disc design.
(Completed Disc)
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The lock disc is made from birch, which is not a particularly good match to the redwood. I'm thinking I'll paint it white, along with the smaller disc, to match the white swing frame. I'll post pictures after painting.
More soon,
John