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 ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users