PSN-L Email List Message

Subject: Re: Real time traces
From: Karl Cunningham karlc@..........
Date: Fri, 21 Aug 2009 13:57:26 -0700

Hi Brett,

Thanks for the reply.

I have a mechanical design question about your sensor. Did you do any 
thing special with the spring anchor / clamp mechanism?

For some time I've been focused on creep when leaf springs are clamped 
and stressed. The thought is that when the spring gets bent, the stress 
in the outer fibers of the spring will be beyond what the clamp can 
retain. This is especially true right where the spring emerges from the 

In some of my experiments this has caused noticeable hysteresis and 
creep. I surmise the same problem might occur when clamping flexures 
although the stress is bound to be much lower than in a leaf spring.

Possibly some of this can be dealt with by stressing the spring and then 
clamping it, and maybe even artificially aging the assembly after clamping.

Ideally the spring would be made with thicker ends for clamping but this 
is obviously impractical for our purposes.

I'm curious if you did anything to help mitigate this effect.


Brett Nordgren wrote:
> Hi Karl,
> Good to hear from you again.
> We're working on finishing up the docs and I'll keep you updated on 
> what's happening.  Can't run my CAD program and keep up with WinSDR at 
> the same time (running at 200SPS), so am setting it up on another 
> computer.  Then back to documentation.
> For starters we just began by posting waveforms, but it shouldn't be too 
> long before the docs are ready for prime time.
> Regards,
> Brett
> At 09:11 PM 8/20/2009 -0700, you wrote:
>> Hi Brett,
>> Please excuse the tardiness of this reply.
>> Congratulations on your progress and good looking data.
>> I can see from the photo on the web page roughly what the instrument 
>> is and how it's constructed. Other than the links already mentioned in 
>> this thread, have you published a description of the design and/or 
>> schematics of the electronics?
>> Sorry if this has been covered here before. I've been away from 
>> monitoring the PSN list for some time, and a brief review of the 
>> archives didn't turn up a description.
>> Curious minds want to know...
>> Thanks.
>> Regards,
>> Karl Cunningham
> Watch our wiggles
> or watch some very very good wiggles
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