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I prototyped this attractive wooden sit/stand laptop stand

this attractive wooden sit/stand laptop stand

but ran into a problem keeping the legs tight enough to hold their position. There are 1/16" thick EPDM washers between the oak legs - the washers are almost 1.25" in diameter with a .25" hole for a threaded tension rod. If I want to resist about 15 lbs of force on a 8" lever arm, that's only about 10 ft-lb of torque that I need to resist. What the hell, let's say 20 ft-lb.

I tried to find a toothed washer that I could use in pairs, each one epoxied to one of the oak legs, but couldn't find a suitable design. (For example the Nord Lock wedge locking washers won't work because they are directional. They will work on one side, but on the other the rotation will be in the wrong direction.)

What alternative material(s) should I use which might resist that rotation?

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    $\begingroup$ Don't they sell left hand turn Nord locks, and right hand turn? $\endgroup$
    – John Alexiou
    Jun 7, 2018 at 2:11
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    $\begingroup$ Nord locks only provide anti-vibration properties in one direction, but will do increased holding torque in both? Why not epoxy the “big shallow teeth” to the outsides, and have the “small teeth” of the nordlocks interfacing with each other? This would give more individual angles/steps, too $\endgroup$
    – Jonathan R Swift
    Jun 7, 2018 at 12:53
  • $\begingroup$ If the "small teeth" are deep enough to mesh together, then yours is an excellent suggestion. @ja72 - I will ask them. Thanks to you both. $\endgroup$
    – Rickmakeitquick
    Jun 7, 2018 at 16:29
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    $\begingroup$ Fix the compression tube to the inner struts (adjustable, with pin or grub screw) and the tension rod to the outer struts. Use a pair of torsion springs just inside the struts to torque the rod/tube combo. This reduces the clamping force needed. Relieve the inner face of one strut to a diameter of 5/8" so that only the outer part of the washer is under compression. This gets you more holding power for a given dog torque. Consider a cam clamp and lever instead of a dog knob. Like on bike wheel quick releases. They start at about $7. $\endgroup$
    – Phil Sweet
    Aug 5, 2018 at 15:22
  • $\begingroup$ @PhilSweet I follow you -- and would never have thought of this combination of solutions. Thank you!! $\endgroup$
    – Rickmakeitquick
    Aug 18, 2018 at 18:24

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I think this old lawn chair gear would work for you well. It should be old enough where the patient on it has expired.

enter image description here

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