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From: Tim Wescott <t...@seemywebsite.com>
Subject: Re: Mounting Conundrum, Revisited
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On Tue, 13 Nov 2012 17:55:15 -0500, Jim Wilkins wrote:

> "Tim Wescott" <t...@seemywebsite.please> wrote in message
> news:qo-dna9a1_x_Ij_NnZ2dnUVZ_oidnZ2d@web-ster.com...
>>>
>>> This is a pretty neat training gizmo for control loops. Sort of like
>>> the
>>> ball balancer, but better.
>>
>> I considered doing a ball balancer, but I figured this would cost less.
>>
>> For that matter, I really wanted to do an inverted pendulum -- but I
>> couldn't see how to do the mechanism cheaply.
>>
>> The wheel collars stayed tight on the flight home, yet the pot was
>> still
>> punched off the board.  Not by as far -- but all leads broken is still
>> all leads broken.  I suspect that any sort of collar that rides close
>> to
>> the board to limit travel in that direction will either rub or have too
>> much play to be safe -- but I could be wrong.
>>
>> At this point what I see is a choice between some rotational slop
>> between
>> shaft and pot (which messes up the educational value of the thing), the
>> current setup (which leaves it fragile, but possibly manageably so),
>> some
>> sort of a flex coupling or spring (assuming I can figure out how to do
>> that well and cheaply), or some sort of a spring-loaded means of
>> holding
>> the shaft-pot joint to be snug in rotation, but still low friction to
>> axial motion.
>>
>> --
>> Tim Wescott
>> Control system and signal processing consulting www.wescottdesign.com
> 
> http://www.dynapar.com/uploadedFiles/_Site_Root/Technology/White_Papers/
Encoder%20Mounting%20WP.pdf
> #3, Direct mount with tether. The tether might be the connecting wires.
> jsw

If I use this pot then my situation is just about backwards from their 
assumptions: the pot _doesn't_ have bearings, and by construction its 
designed to be soldered onto the board.

-- 
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com