Re: More paddles and keys ...
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Hello Jim, W0EB,
The 'engineering drawings' are not so much engineering as just rough design drawings. The finished key is closer to this, than the first one I posted (my first drawing):
The thing about a drawing is that is easy to change.
Change is the only constant.
My main concern was to not have to drill and tap holes in the 1/2 inch thick steel base.
So this is kind of what the drill holes looked like when I was done:
I used 8-32 brass screws throughout the key.
A #20 drilled hole just allows an 8-32 screw to fit through.
I used heat-shrink for screw insulation on the DIT/DAH binding posts and contact posts.
So therefore, a #11 drilled hole was used to allow the insulated screw to fit.
I used plastic mayonnaise jar lids, cut to size for DIT/DAH post insulation.
The whole key is ground except for the DIT/DAH binding and contact point posts.
You can see that the dimensions are not exact. I held a ruler up to my monitor and got dimensions as close as possible. But they are not exact. I used a raster graphics program called Kolourpaint4 to make my drawings. If you want to be exact, use your favorite CAD program, or dust off your drafting table, T-square, and sharpen a pencil. ;-D
The 3/16" hole is for the rear post for the levers. Use a 1/8" post for paddles closer together.
I couldn't find any 1/8" brass rod in the shop, but had a 3 foot length of 3/16" brass rod, so I used it.
I used #11 holes for the posts so I would have a tiny bit of wiggle room for adjustment.
As you can see, I used two screws on each brass post to fasten them to the brass lintel.
But I only used one brass screw to fasten each post to the steel base. Less drilling through steel.
(Not to Scale)
I broke one end of a 3/16" center drill when drilling the pivot holes in the steel base.
As a result, I ended up moving the pivot holes in the steel base, back 1/4".
I had two plans for getting the pivots lined up.
Plan "A" was for pivot holes in the steel base.
Plan "B" was the alternate plan in case Plan "A" didn't work.
Plan "A" worked out to be close enough, so I went with it.
My main inspiration for my brass and steel DIY Dual Lever Paddle was a Vibroplex Iambic-S.
I looked at a lot of pictures on the Internet while I was designing my paddle.
Some things were designed because of the materials available to me.
For example, the 1/2 inch thick 4x5 inch steel base was cut from a 4" wide piece of steel.
I did not feel like cutting it smaller, so 4" wide was what I went with. I cut 5 inches off of 12 inches.
I used 8-32 brass screws because there were not enough 10-32 knurled nuts at the hardware store.
I bought ten 8-32 brass screws 1 1/2 inches long, with a hex nut and a knurled nut for each one.
I ended up buying ten more screws. I cut them to length with a jeweler's saw frame with a 2/0 saw blade.
I guess the main thing is to be flexible. Drawings are not chiseled in stone.
I think you will have much better results with your milling machine.
I look forward to seeing what you do.
Ken, KM4NFQ "Not Fully Qualified"
On Mon, Nov 11, 2019 at 12:08 PM Jim Sheldon <w0eb@...> wrote: