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Sunday, February 11, 2024

Tripod Legs

Why am I telling you this?  I doubt it interests any of you.  This is a collection of notes for later and writing it out helps to visualize what it will look like when I build it.

This is an area that I have just started imagining.  An outer leg perhaps 1/4" by 1/4" inside and an inner leg 1/8" x 1/8".  A little extension on the center 3/8" plate of the mount.  A slot in each extension 1/2" cos 30 by 1/4" allows the leg to go vertical for transport; at the preferred 30 degree expanded angle the top of the outer tube hits the inner part of the extension to prevent it from going beyond 30 degrees. 

A 1/4" stainless steel clevis pin acts as the axis on which the leg rotates.  I could use a conventional clevis pin to keep it in place but a machine screw secured by a nut seems more secure.

The lower narrower leg will have rectangle with a hole epoxied to the top of the tube of a size that stops in a similar rectangle with a hole in the bottom of the outer leg.  The inner leg slides into the outer leg from the top.  Both legs have a 30 degree cut at the bottom (or is it 60 degree?  More obvious when I am ready to cut).  This way, even if the inner leg is not extended it will sit flat on hard surfaces.

The base plate for the mount is only 2" diameter and 1/4" thick.  I think this will the most complex part to cut.  I will mount this part on a rotating table.  The rotating table has a 3/4"-16 thread. I will tap a 3/4"-16 hole on the under side of the plate.  This still gives enough space to mill around.  (If the price to get DragonPlate to cut me a 4" circle, all the better.) The program will make a cut from the exterior into the 2" diameter.  As I slowly turn the rotating table to cut the inner diameter, it will make the 2" diameter.  

At probably 105 degrees, the mill will move out to 3" diameter and i will very slowly rotate to make the exterior section which will hold the leg.  Rotate until I have created enough room for the leg slot.  The program then cuts back in again.  Repeat twice more.  

Then the program lifts the mill up and positions it to cut the leg slots as rectangles. Repeat twice.  If Sherline has its manual to CNC conversion for rotating tables available by that point I will use that instead of rotating table by hand.  The mill controller has an A cable for the CNC table.  More programming which I will test on acetal first.

1/4" square tube not available from DragonPlate.  1" and 3/4" instead.

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