Getting that alu tape drum off the shaft so you can fit something else is a problem, they are pressed on, interference fitted.
I think I'd try a nutcracker. Sent from my Kyocera Rise Gene Heskett <ghesk...@wdtv.com> wrote: >On Thursday 04 April 2013 09:23:01 Gregg Eshelman did opine: > >> --- On Thu, 4/4/13, John Stewart <alex.stew...@crc.ca> wrote: >> > I'm looking for ideas here. >> > >> > A Unimat SL1000, MK1 landed on my desk last Saturday. It's >> > mine if I want it. Have been thinking of taking some of my >> > CNC parts kicking around home and using them, but I don't >> > think using a 5i25 + 7i76 + Nema 34 steppers is great. >> > >> > So, with a little lathe like this, if I go with NEMA 17 "3D >> > Printer" steppers (think Reprap or one of the Thingverse >> > machines), what would be the best, least expensive way of >> > driving these steppers from a LinuxCNC setup? >> >> Even 17's would dwarf that Unimat. I'd try some motors from printers or >> old 5.25" full height floppy drives. I just happen to have a pair of >> Tandon single sided 5.25" drives I've been trying to give away for a >> while. ;) Had them on a TI-99/4A years ago before upgrading to double >> sided drives. >> >> The drive motors for spinning the disks might also be useful for micro >> CNC with encoders added. I think they have tachometers built in. >> >They would probably be pretty puny for x-z drives even on that small a >lathe. They were normally belted to the spindle, and belt slippage on the >lathe would destroy any accuracy unless you also put scales on it. The 17 >class steppers might be overkill. but at least you can microstep them. > >> Even cooler would be using the motor control boards from the drives. >> They do step and direction for the head steppers and on/off for the >> drive motors. 'Course they have rather poor resolution with only 40 >> normally accessible steps, though that's not a hard limit, there was >> software for increasing the number of tracks on disks for some >> computers. > >Steps available are virtually unlimited. The driver SW in the computer >usually steps them outward, either until it hits a mechanical limit & sits >there hammering the stop till enough steps have been issued that the >computer knows it has to be at track zero ( racket you hear at bios bootup >from any pc with a floppy in it, or if fancy driver, the track zero switch >closes to indicate its at track zero. Stepping the other way is limited in >the drive by the head carriage hitting the spindle mechanics but if that >limit is removed, there is not any other limit. > >The biggest problem will be the low voltage it runs on. The disk drives >board will fail at the voltages we commonly use for steppers, even the toy >stuff we generally use is 24 volts, and that is enough to cook the floppy >board because they do not chop for current control, they power up, do the >step and shut the current off 40 milliseconds or so later if no more steps >come in since there is not any torque pushing on them, the normal steppers >cogging is sufficient holding power. > >The next problem is the speed they can step. At the voltages they do run >at, and at no more mass than they have to move, the maximum step rate is >nominally 6 ms per step. Mechanically geared down for accuracy, that is >not going to be very fast at all. > >Synopsis: Look for a small chinese stepper board that can microstep with >chopper controlled current, and hit the surplus places looking for 4 wire, >not more than 12 volt, probably $12 or so, steppers. I have a few, rated >at 24 volts, which means they'd be pretty slow on 24 volts, but I didn't >buy them for motors, but as generators, turned by hand they output a nice >pulse for a jog pendent. But my round tuit came up missing. :) > >Those head steppers out of the old tandon's that drive the head carriage >via the thin steel tape, can be made to put out considerably more torque, >and faster by 5x or so, if driven by a xylotex board and a 24 volt supply. >But the xylotex board doesn't do idle current reduction, just on & off via >the enable pins, so the motor temps need to be watched. Getting that alu >tape drum off the shaft so you can fit something else is a problem, they >are pressed on, interference fitted. > >Interesting what if problem. :) > >> I wonder if it'd be possible to hack the control board (which is >> separate from and much smaller than the data read/write board) to work >> as a more general purpose one? Microstepping might be a bit much to >> add. > >Not practical at all. > >> There was a site that showed using the boards and motors from a pair of >> floppy drives to build a robot, but it vanished. > >No wheels there that we can't reinvent if needed. :) > >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) >My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! >My views ><http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> >... My pants just went on a wild rampage through a Long Island Bowling >Alley!! >A pen in the hand of this president is far more >dangerous than a gun in the hands of 200 million > law-abiding citizens. > >------------------------------------------------------------------------------ >Minimize network downtime and maximize team effectiveness. >Reduce network management and security costs.Learn how to hire >the most talented Cisco Certified professionals. Visit the >Employer Resources Portal >http://www.cisco.com/web/learning/employer_resources/index.html >_______________________________________________ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Minimize network downtime and maximize team effectiveness. Reduce network management and security costs.Learn how to hire the most talented Cisco Certified professionals. 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