[chbot] slow motor

[Robin Gilks]

Thanks for the ideas

Some of the experiments I've done with drill motors have been a real
disappointment. By the time I've got the speed down to about 1rpm there is
just no torque - certainly not the 10kg pull I get with the existing setup.
Adding more gearing is not viable at this time of year - too much else to
do!!

A  bit of background I think to what I'm up to.

I'm refurbishing an existing system so of course I want to make minimal
changes.
In order to simplify the mechanical linkage I opted a few years ago to open
the window(s) with a spring and pull closed with a stainless wire on a
capstan driven by a wiper motor. Much easier than pushing rods. The springs
are from a slab garage door mech so are just wound up on a 25mm tube and
all the parts seem to be easy to get from the dumpster at the garage door
manufacturers workshops (springs, tube, bearings, clamps etc). The pull
wire has stops fixed to it that hit the limit microswitches to cut the
power when fully open or closed.

It's this simple basic system I'm trying to duplicate for a second window
hence the need for another motor. The controller I made some 6 years ago
already supports a second motor with independent sensor as well as remote
control using a NRF24l01. Details at https://github.com/g8ecj/tunhouse It
runs on either an Arduino nano or a stm32 blue pill.

For the moment I'll just set up the one motor I already have and continue
to see what else I can use.

Cheers


On Thu, Nov 18, 2021 at 11:14 AM Charles Manning <cdhmanning at gmail.com>
wrote:

> I have not seen the mechanicals you're working with, but maybe something
> like a drill and a screwjack would give you all the beans you ever need
>
>
> https://www.window-openers.com/wp-content/uploads/2015/11/screwjacks-selection.png
>
> You might even be able to knock something up using threaded rod etc.
>
>
>
>
> On Wed, Nov 17, 2021 at 7:34 PM GRAHAM CHRISTIE <
> development.engineering at xtra.co.nz> wrote:
>
>> Hi Robin
>>
>> If you had the drill driving a small diameter shaft and rope,(I use 3mm
>> for boats all the time Oborns Nautical or Burnsco)
>> https://obornsnautical.co.nz/products/dyneema-double-braid-3mm?_pos=2&_sid=d79ef86f6&_ss=r
>>
>> And then run this through a pulley system, 2:1 or 3:1 or 4:1 just
>> depending on how much you want to slow it down and increase the pulling
>> force.
>>
>> I have done this in the past with a closed loop rope system so that you
>> can drive it and pull in both directions.
>>
>> I personally use the little marine pulleys, but for cost pulleys can be
>> made from just about anything.
>>
>> Regards
>>
>> Graham
>>
>>
>> On 17 November 2021 at 19:10 Andrew Errington <erringtona at gmail.com>
>> wrote:
>>
>> Depending on which part of the original motor assembly died could you
>> combine the electric drill motor with the worm gearbox?
>>
>> If it's going too fast could you put a PWM speed controller on it?
>>
>> Andrew
>>
>> On Wed, 17 Nov 2021, 18:29 Robin Gilks, < gb7ipd at gmail.com> wrote:
>>
>> Greetings all
>>
>> I've followed up the suggestion of using a cordless drill for my low
>> speed motor to substitute for a wiper motor..
>>
>> Investigation of 9.6, 12 and 18v drills that have gone the way of nicad
>> batteries have shown me that they all spin way too fast and have nothing
>> like the torque of a wiper motor.
>> This is mostly due to the gearbox rather than worm drive the wiper motor
>> has. The added advantage of the worm drive is that it can't (easily) be
>> driven from the output side so no brake is required.
>>
>> So back to Monday night's question, does anyone have a wiper motor going
>> spare? Permanent magnet (i.e. reversible) with a simple shaft out rather
>> than an internal cam or crank..
>>
>> Cheers
>>
>> --
>> Robin Gilks
>>
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