On Friday 28 March 2008, Gene Heskett wrote:
>On Friday 28 March 2008, Ian W. Wright wrote:
>>Gene wrote...
>>
>> >>>>>>>>>>I also don't know about the
>>
>>bearings, I'd think ball cuz sleeved stuffs usually have more end-play than
>>could be tolerated in a spiral groove drive setup.>>>>>>>>>>>>
>>
>>you might need to look at those motors carefully - some of them only had
>> very rudimentary bearings in the front of the motor and relied on a simple
>> steel ball sitting in a dimple in both the motor back bearing and at the
>> end of the screwed shaft. A lot of the little 3 1/2" floppy disk motors
>> now use the same technology. Have you considered using the innards of a
>> mouse to make an encoder such as - http://tinyurl.com/3awsou ? A dead
>> computer printer will probably give you a couple of usable motors but they
>> are often only 48 step.
>
>These have oil-lite sleeve bearings on both ends, I can see them. And they
> do seem to be 200 step/rev. I believe my friend has more of them cuz when
> he gets an itch, he buys enough surplus of whatever he's going to use to
> scratch that itch to last him for his projected production run. That,
> after 8 or 9 years, is never gonna happen, and I suspect the batch this one
> was one cell occupant of an egg crate full of them can be supplanted with
> however many more I might need for a 5 dollar bill or less each. Probably
> a lot less.
Update, I take it back, I believe this motor is a 7.5 degree/step motor.
Further observations. I have made a dial knob, 1/2" thick HDPE, about 2.25"
in diameter with a 1/4" center hole that I just pressed onto the motors
output gear and a finger dimple to spin it with. The mass of the knob helps
to reduce the distortions of the output waveforms considerably, and I would
expect that if the motor was mounted solidly in a panel, we could go to
virtually zero speed without losing a step. I'm still getting over 2 volts
of signal out of it at about 1/5th of an rpm when turning it by hand.
My friend apparently wasn't the src of that motor, so I'm going to look for
something I can get in 10'sies & recheck how those might work, I have some
1.8 degree stuffs spotted that look like the head motors in those older
floppies so I'll get those on order ASAP.
I'm thinking that, from my observations here, a strong detent action may not
be ideal unless the knob represents a pretty massive flywheel to smooth out
the output waveforms. One such motor I have rings like a bell when turned
step by step by only my fingers on its output gear, which would generate all
sorts of garbage for a signal, it would need to be bolted solidly, and a knob
weighing several pounds to dampen that to usability at slow speeds. The
motor from a disk drive would, from what I see here, need at least the old
handwheels from my mill for mass to smooth that out. And that means they
would hang out way past the edges of a suitably sized Bud-Box.
Digging this up and trying it is fun folks, stay tuned.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
I have ways of making money that you know nothing of.
-- John D. Rockefeller
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