Hi Geoffrey;

On Fri, Jul 24, 2009 at 5:11 PM, Geoffrey  wrote:

> Hello Meredith lamb,
>
> There is one other question I may ask ;
>
> Have you ever tried a torsion spring
> with this design ?
>
> I have tried using an aluminum alloy
> antenna element that is a tube split down
> the middle with a slot its full length.
> It seems to act as a spring quite well
> but not sure if its actually suitable for the job.
> It would totally eliminate the bulky extension spring.
>

*** No I've not tried a torsion spring; but I get the idea.   I think I'd
rather stick with the traditional
extension spring route for the time being.

>
>
> If you wish to derive the spring constant
> you can hang a water bottle with a measured
> amount of water to get enough weight to
> extend the spring maybe 10 inches then use
> a bit of math. You may control the overall temp
> of a working device ( I think two devices are necessary
> to be proper ) by placing gallon jugs of salt
> water brine surrounding the devices to make a thermal
> inertia to average out temp changes or so
> I believe.
>
> I think any linear constant extension spring made out of
> steel can do the right job if you can get at least
> 11 or more inches of extension.
>

*** It entirely depends on the spring used of course.  The original cut
Georgia tech spring (unloaded) was 4" length;
and loaded it "looks" like ~ its perhaps 8".

>
> You must allow for any pretensioning because
> that will have an effect on its overall extension.
> The pretensioning will work out to some added
> extension amount to the measured results.
> Sort of a second degree correction factor
> to think about. That is how much water weight before
> spring shows first signs of extension.
>

*** I think a simple adequate weight scale would work to derive such and
about any kind
of add on weight.

>
> No reason you can not easily work out the spring constant
> for amateur needs.
>

*** I'll give it a go.

>
> I like your Georgia Design But would absolutely need two
> such sensors for a complete whole.
>

*** You mentioned measuring tilt that way earlier; but I don't think its
that necessary.

>
> Please use eye protection, I blinded
> myself in one eye accidentally
> with a wild spring once, thank
> goodness it lasted only a few seconds
> before returning to normal.
> Springs can be dangerous to anyone's
> quality of life. No one is mistake free.
>

*** Yes, I've also been "bitten", whacked or cut a few times

>
> Also Century Spring Company, they will build custom
> springs but charge a terrible initial setup fee of a
> few hundred dollars I think. You want to have
> maybe a hundred springs made all at once.
>

 *** I won't be in production; I'd rather find/use something already on the
common hardware market.


Regards;

> Geoff
>
> *** Take care, Meredith Lamb
Hi Geoffrey;


On Fri, Jul 24, 2009 at 5:11 PM, Geoffrey <gm=
voeth@...........> wrote:

Hello Meredith lamb,

Ther=
e is one other question I may ask ;

Have you ever tried a torsion sp=
ring

with this design ?

I have tried using an aluminum alloy
antenna e=
lement that is a tube split down
the middle with a slot its full length.=

It seems to act as a spring quite well
but not sure if its actually =
suitable for the job.

It would totally eliminate the bulky extension spring.

=A0
*** No I've not tried a torsion spring; but I get the idea.=A0=A0 =
I think I'd rather stick with the traditional
extension spring route for the time being.


If you wish=
 to derive the spring constant
you can hang a water bottle with a measur=
ed

amount of water to get enough weight to
extend the spring maybe 10 inche=
s then use
a bit of math. You may control the overall temp
of a worki=
ng device ( I think two devices are necessary
to be proper ) by placing =
gallon jugs of salt

water brine surrounding the devices to make a thermal
inertia to average=
 out temp changes or so
I believe.

I think any linear constant ex=
tension spring made out of
steel can do the right job if you can get at =
least

11 or more inches of extension.

=A0
*** It entirely depends on the spring used of course.=A0 The original =
cut Georgia tech spring (unloaded) was 4" length;
and loaded it "looks" like ~ its perhaps 8".=A0=A0

You must allow =
for any pretensioning because
that will have an effect on its overall ex=
tension.

The pretensioning will work out to some added
extension amount to the me=
asured results.
Sort of a second degree correction factor
to think ab=
out. That is how much water weight before
spring shows first signs of ex=
tension.


=A0
*** I think a simple adequate weight scale would work to derive such a=
nd about any kind
of add on weight.

No reason you c=
an not easily work out the spring constant
for amateur needs.


=A0
*** I'll give it a go.

I like your Geo=
rgia Design But would absolutely need two
such sensors for a complete wh=
ole.


=A0
*** You mentioned measuring tilt that way earlier; but I don't thi=
nk its that=A0necessary.

Please use eye =
protection, I blinded
myself in one eye accidentally
with a wild spri=
ng once, thank

goodness it lasted only a few seconds
before returning to normal.
Spr=
ings can be dangerous to anyone's
quality of life. No one is mistake=
 free.

=A0
*** Yes, I've also been "bitten", whacked or cut=A0a few=
 times

Also Century Sp=
ring Company, they will build custom
springs but charge a terrible initi=
al setup fee of a

few hundred dollars I think. You want to have
maybe a hundred springs ma=
de all at once.

=A0
=A0*** I won't be in production; I'd rather find/use something=
 already on the common hardware market.
=A0
=A0=A0=A0
Regards;


Geoff


*** Take care, Meredith Lamb