Hi Rob, I've long had a decent stepper motor I picked up on ebay, and I've got an eight inch rotary table which I want to "digitize", as the crude scratches for marks are hard to be accurate with, and I'm waiting on a cutter to mill the cams of the radial engine I'm building, so I thought I'd find a motor drive kit somewhere, and see about making this stepper motor a permanent part of the rotary table. I worked in electronics for about thirty years too long, never liked it much except the first couple of years when it was all new, and I was building ham radio receivers and transmitters that used tubes, but I got shoved into electronics when I was in the Marines, because I already knew it, and finding a good technician is like finding a good mechanic for your odd and unusual car or tractor. You don't let go, once found. I still know my electronics, but most of my knowledge is geared around antique equipment, as my knowledge of tubes was taken advantage of, as tube theory was no longer taught by the time I went into the field, and all our C-130s we used for refueling, were still using electronics from the thirties and forties. I do know transister theory, and worked with modern electonics, even teaching it while in the Corps, but it's been fifteen years or so since I retired, and I never did really work much with modern electronics, so I'm learning as I go. Eventually, I will convert my Enco bridgeport clone to CNC, and probably a lathe or two, but I've got some learning to do first.
I'm focussing on motor drives to start with, I've also got a nice little atlas shaper I use quite a bit, but down feed while cutting is a bit of a pain, and hard to keep an accurate control of depth, and I think a stepper motor would be an easier "fix" than devising a ratchet drive that works with the down feed in all positions and has feed choices. I've been looking on the web for motor drive kits, and the bug right now is selecting the right one for the motor I already have, but I will be happy to chime in on any other project with any help I can, since I do have a solid understanding of the field of electronics, I'm just not up to date on all the new parts and pieces - the principles and rules haven't changed though, ohm's law still rules, and the new parts are generally easier to understand as a whole, than were the box of parts necessary to do the same job using discrete components. Most of your use of resistors and the like are for control of input current or volts, or for shunting feedback to ground, with all the "work" being done by the integrated circuit, which was once made up out of individual parts and thus finiky demanding components that were complementary. Working on digital equipment is more about logic than electronics theory, and except for power supplies and the like, it's mostly either on or off, which makes digital electronics easier to get into without getting in over your head.
My intent with the rotary table is a stand alone device with the expectation of getting into more advanced work ending up with converting my mill and lathe at some time, and having to learn how to interface with a computer between now and then, and deal with the programing when it comes up. I've built a few Vellman kits including a couple of chopper type motor drives and used them, but it makes more sense going with stepper motors and digital electronics today, than just variable speed, which is all I got from the chopper type motor drives. They are good if all you want is power feed, or movement and are content with a knob to vary the speed, and a switch to start and stop. I did the kits mostly to get my hands back in and get comfortable with the work again, having left it behind for lots of years. I will do a build log on the rotary table, and everything else I do until someone says I'm taking up too much space. Ta ta for now,
mad jack
