RE: Whoooosh..thud..oh bugger

["Phil Harris" <phil@xxxxxxxxxxx>]

Have you thought of selling the current design to the producers /
directors
of the next "Cube" film?

:-D

If the current design is cable operated then is there any way of
spring-loading one or more of the pulleys / mountings / cable attachment
locations so that there are one or more shock absorbing elements in the
system?

Phil

> -----Original Message-----
> From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
> Of Martin Howell
> Sent: 04 April 2007 10:35
> To: ukha_d@xxxxxxx
> Subject: [ukha_d] Whoooosh..thud..oh bugger
>
> This is not really HA, but it's close.  My massive
> electrified sliding door project is almost completed, but
> now that the glass is in and the weight of the door is up to
> maybe 70Kg, the intertia of the door kinda mashes the drive
> cable mechanism when the drive motor stops and the door
> tries to keep on going.  This was the main logic behind
> electric drive, as I wanted to avoid small boys being
> squashed when the door was closed too enthusiastically
> (though quite why, I'm not sure, it seems the sort of thing
> that small boys deserve :-))
>
> I could install stronger cables etc but that would not
> really solve the problem, and a mechanical braking system
> will still put too much strain on the drive train.  Instead
> I'm looking for some electronic means of starting the drive
> off slowly, then speed up, then slow down as the door
> reaches the end of its travel. It would be easy to fit
> microswitches to change from speed A to speed B, but the
> drive electronics are beyond my limited skills - I can build
> a circuit, but can't design one.  The drive motor is 12v (as
> is all the electric gubbins), and the current obviously
> reverses each time the motor changes direction. The
> mechanism is presently operated by a pair of standard car
> electric window switches, so they drive the motor when
> pressed and it stops when the switch is released.
>
> Anyone have any ideas?  Thanks
>
> Martin
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