A couple of other problems with starter motors:
(Besides being expensive) The require HUGE amounts of current... As
anyone who has tried to start a cold car with a 'not-so-new' battery
knows! The initial start-up current can run into, in some cases,
scores and scores of amps! (Score=20, in case anyone forgot) That
sudden surge can fry even some of the most robust power supplies,
which again, will add to expense, since you would be forced to use a
power supply that is sheer overkill for the job at hand. Another
problem, related to the previous post on this, is not only does the
output shaft going to give you headaches, but to really make the
thing work, you will need to deal with what is often called
the 'Bendix', (A trade name) which is often used to describe any
version of starter drive gear. This gear is designed to engage when
the starter motor first starts, and dis-engage once engine speed
exceeds the starter motor RPMs. It's all done with a helix cut into
the shaft combined with a spring. And all this has to have something,
(Normally the teeth on the flywheel) to 'work against'. Starter
motors are also heavy. Could one be made to work... Yes... But then
you still have the problems of stop limit switches, and these starter
motors are NOT designed to run in reverse. (Imagine what would
happen to your flywheel if they could run backwards! Uh, ugly to
even think about) The 'Bendix' will not work in reverse, even if the
motor would. (And it could be made to do so, it's just a DC motor,
after all... but the headaches wouldn't be worth it!) So then, how do
you set the starter motor to stop after a set number of revolutions?
Could be done, sure, but again, more headaches. Even with the starter
drive grar removed, you have to hook it all up somehoe, and as the
other post correctly pointed out, this wouldn't be all that easy.
As for building the car door into the wall of the chicken coop, or
even doing away with the coop and just using the whole car, that
person obviously has never mucked out a barn! I have! (I realize the
comment was toung-in-cheek... I HOPE!) Starter motors also tend to
run hot, not a good thing around a lot of straw, hay, or the like.
Normally, a starter motor should never be run for more than 30
seconds with 5 minutes cool down between running again for another 30
seconds. (I've seen a lot of burned out starter motors that were
cranked for too long, and the damage usually dosen't stop with just
the motor) You also will need one very heavy duty solenoid to start
the motor. If you DO go this route, use FORD parts... Theis solenoids
are easy to set up and to even by-pass if needed. Many starters now
have the solenoid incoperated into the body of the starter, and so
would be harder to get to the wires needed for control.
So, for all those reasons, and more, an engine starting motor would
not be my first choice. As I said before, the car window motors are
almost made to order for your use. The only thing you might want to
add would be a fail safe, or a waaaay for the door to stop in case
something, like a chicken, gets in that way. Here, garrage doors DFO
have an edge, all newer ones already have this ability built in, it's
the law now. But it would not be hard to design something for this.
(Did I mention that I once worked for SEARS? As a lawn & garden tech.
That was supposed to mean small, air cooled engines, but somehow,
SEARS decided that also meant garrage doors, power tools, and gas
grills. I went to Briggs & Straton school, and hired on with SEARS as
a small engine mechanic, but I was forced to learn these other things
as well) A garrage door opener WOULD word work... but there's a lot
of converting you would still have to do. The car door window motors
are already setup to do what you need. To add a saftey, for that one
straggler chicken, I would just add a light beam and sensor, in
circuit with the ON switch, either visable light or IR. Break the
beam and it would stop the current to motor via a relay to the power
supply, or tied into a stop limit switch. If you would like details,
write me off list, and I'll be happy to help.
--- In email@example.com
> automotive starters will require gearing and it's harder to attach
pulleys or gears to that spline
> how much DIY skill on the farm? soldering? PCB artwork?
> I prefer old GM power window motors- leave the big lever attached
> a battery charger for a power source
> now you get into the relays to reverse direction , limit switches ,
> --- In firstname.lastname@example.org, "Merrill MacMillan"
> > Hi Donna
> > Interesting problem!
> > An automated garage door solution would be your best option.
However, if you want to save a few dollars, be prepared for a lot of
> > I live in Canada where weather is always a factor, mainly in
winter. Ignoring this issue and assuming the chickens go inside
before dark, I would suggest you use one motor with lots of pulleys
and ropes. You could probably use an old starter motor and solenoid
to open the doors with an elevator style brake to hold the doors open
and let them down slowly. Every farm has an old car or tractor that
can donate these things. All you need for power is an old 12 volt
battery. Just charge it overnight once per month.
> > Merrill
> > if it's automated how do you know the chickens are on
> > the correct side when the door changes state?
> > --- In email@example.com, "Donna Kaiser"
> > > Hi All,
> > >
> > > I came here hoping that someone here could help me out. I want
> > > build an automatic chicken coop door opener, and I don't know
> > > parts to use or how to do it.
> > >
> > > I have six chicken doors in my barn that are all rigged to
> > > vertical tracks when pulled up by their strings. I was thinking
> > > rigging them each to pulleys to a central line, then by pulling
> > > one central line, I could open all six doors at once (and later
> > > them). Their total weight is maybe 10-15 lbs.
> > >
> > > I want to rig a way to automate the one central line such that
> > > time each morning the central line is pulled tight to a certain
> > > degree, then at Y time at night the line is loosened to the same
> > > degree.
> > >
> > > I thought of using a garage door opener, but was hoping to come
> > > with a smaller and cheaper solution. I thought maybe a motor
> > > be used, and when a switch told it to actuate, it would crank
> > > certain amount, like a winch, then when the switch went to the
> > > mode, it would uncrank the same amount.
> > >
> > > Ideally, the use of a cheap light timer (the kind you use to
> > > your lamps to turn on a x time and off at y time when you are on
> > > vacation) would start and stop the operation. I have
> > > the barn. But I don't know what kind of motor to use or where
> > > one, and how to tell the motor to do this.
> > >
> > > I could get the help of someone good enough at electronics to
> > > instructions if you could help me figure out how to set this up.
> > >
> > > I realize that this is more mechanical in nature than
> > > but I hoped that this board would have the kind of talent
> > > help me out.
> > >
> > > Thank you sincerely for any help you could provide. I am very
> > > resourceful if I have an idea how to accomplish this.
> > >
> > > I could provide pics of the environment if that would help.
> > >
> > > Donna
> > > donnaweb@k...
> > Merrill MacMillan
> > +1 613 256-1718
> > merrill@s...