The DMM servo system I have sitting on my bench at the moment has an input to allow the motor to free wheel but still keep the encoder on line. I haven't tried it yet but in theory you could have a free wheel switch to flip when you wanted to move by hand then switch back once in position.
I have not tried playing with this yet and would be a little concerned the servo may hunt a little when you turned it back on from free wheel mode. I dont have much experience with these servos as i have just started to play with the ones i have now so know idea how they will put up with shop use On 17-03-01 05:39 PM, Greg Bentzinger wrote: > Greetings list members; > > With all the talk or ARM vrs AVR vrs all others etc. I have a question for > those who might be able to point me towards a workable solution. > > Back in the early 80's my uncle purchased a HAAS 5C programmable indexer. > This is the hardware that basically was the original foundation of the HAAS > machine tool empire. > > The unit was built on a 5C indexer casting and assy made to spec by Yuasa and > HAAS mounted a unipolar stepper motor inside a finned cast Aluminum cover. > The unit was connected to the control box via 10 foot plastic coated 3/4" > flex with a large 7 pin round Amphenol connector. > > Programming was all done via front panel numeric key pad. Storage allowed up > to 3 programs of 99 lines each. Subroutines and loops were possible. Use with > manual machines used a remote start button, which would single step through > the program. Connection to CNC equipment was via 4 wire connection to provide > a cycle start signal and a cycle complete status return signal. A single M > code was required. Unit had to be manually zeroed during setup and care was > required to compare dial on indexer with display position while running > production as it was an open loop system. > > Sadly the control has died, and looking inside the box shows this was built > almost 100% discrete components and of the few IC's that are used most have > been out of production for a decade or 2. HAAS basically told me I was SOL > and that they don't have any staff left who understand this dino hardware, > and won't try because key components have been un-obtainium for many years. > > The indexer is very well built and just by not connecting certain pins the > motor can be driven Bipolar, that is the great news. However I will need to > build a controller/driver/power supply unit to run this. > > - - - Now I will say that for my Hurco KM3 kneemill conversion to LCNC I will > let LCNC drive it directly. But Hurco #1 which still uses the OEM control > will need the blind cycle start / cycle complete interface with all 4th axis > programming done in the indexer control. I also have manual mills and drill > presses etc. where I will require the stand alone functionality. > > > Using LCNC for the stand alone control seems like using a nuke to blow up an > ant hill. > > I tried using an Arduino to run an automated bullet lube sizer machine and it > was a dismal failure. Not sure if the stepper drive or stepper PWS was > causing the issues with the Arduino but when I drove the system via LCNC it > worked exactly as programmed. The Arduino would sometimes fail to set the > correct direction and the unit would try to start in reverse near a hard stop > - so it would rip teeth of the belt. Plus the quality of the pulse stream was > hideous. > > Others, however have apparently been successful using and Arduino for a > stepper indexer - but once bitten... I'm trying to use this in an industrial > setting, not like someone trying to spin Nema 17's on there desktop with a > Pololu A4983. I need a solution I can trust. > > I am a Machinist first - though for some reason I seem to be hired for > computer and electronic type jobs more than I make chips. I have no formal > training in electronics so its safe to say I end up having to do constant > research to be able to fix things as they go awry. > > The one problem I don't know how to solve is with a Arduino type system - is > there a way to input the motion program, manually via keypad, into the > controller and have that program stored in nonvolatile memory. > > I have several RPi's - and that is another disaster I intend to avoid - > because it will work fine for a few months then suddenly the SD card is > toast, wipe and reformat and it works fine in cameras or other devices. > Given any length of time a Pi will eventually fail you. And remember this > application requires stand alone capability - no network. > > Now - something completely different and more on topic > > There used to be a retrofit system called ProtoTrak used on Bridgeport type > mills and lathes to allow manual, CNC assist, and in some cases full CNC > control. I was wondering if LCNC could be configured to drive steppers in > velocity mode using a feedback signal split off from the machines DRO scales > to provide near functionality. Velocity mode was due to the fact that I would > use something like O-ring type friction belts not a toothed belt - something > that could be released easily when not needed - even between position moves, > since the control is always tracking position from the DRO. It would require > some type of soft key to enable/disable position holding. The ProtoTrak > system used ballscrews and servos but when you switched to DRO mode it let > the servos freewheel and there was very little drag. OTOH I have used CNC > conversions others have done which retained handles and cranks. Even with the > drivers set as non-enabled the parasitic drag of having to move the machine > plus stepper motor drag was considerable, even on those dinky small motors. > > Even if the system was limited to point to point positioning moves and single > axis power feed (so as to not have multi-axis interpolation errors from a > slipped belt) it could be a great help on manual equipment. > > I'm sure a few of you may have ideas to throw at me. > > Thanks. > > Greg, Out yonder in Yoder, CO > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
