Re: Whoooosh..thud..oh bugger

[Martin Howell <martin.howell@xxxxxxxxxxxx>]

Certainly very much like Cube, every time you press the
button, something unpleasant happens :-) The design is more
like Scrapheap Challenge - the motor came from a Cavalier,
the switches from a Renault Espace, the cables for a
mountain bike gearchange, and the pulleys from a long-dead
photocopier.  I've probably got enough bits left over to
build a small space shuttle, oh yes.

Good idea, the spring loading, but the cables have to be
taut to avoid the door oscillating when it stops/starts. I
did try a foam cushion arrangement to slow the door as it
approached the stops, but although that works ok the force
is just then concentrated in the drive. The motor has a worm
& wheel drive, so when it stops, it stops immediately and
the drive mech has to do the same or something (a joint in
the cable, mostly) has to break.  I think if I can slow it
down as it approaches the harbour wall I could use a current
sensor of some kind to stop the motor when the load is too
high and quick enough not to break anything.

Thanks for the suggestions, I will look at that idea again.

Martin

Phil Harris wrote:
> 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
>> --
>>
>>
>> Grizelli Associates Limited
>> IT Project Consultants
>> 2c Nethermoor Road, Middlezoy, Bridgwater, TA7 0PG
>> UK Company registration no. 2468872
>> VAT registration no. 713 1775 49
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
>

--


Grizelli Associates Limited
IT Project Consultants
2c Nethermoor Road, Middlezoy, Bridgwater, TA7 0PG
UK Company registration no. 2468872
VAT registration no. 713 1775 49