On Friday 26 April 2013 09:19:17 Peter Georgi did opine: > Hi, > > After spending lots of hours during the winter I finaly managed to > upgrade my BF30 to CNC with stepper motors. The X,Y and Z axis run fine > an what rests is > > - turn on/off the spindel with LinuxCNC > - controle the rpm's of the spindel
For non-servo control several people make PWM translators/isolators suitable for starting material. The PMDX-106 (with the full front panel control kit) has worked well for my small mill for several years now. I have no clue how fast it is for use with an encoder to make a full servo out of it for such as rigid threading. The responses I get, from gcode or the local controls, would seem to indicate its fast enough for a servo setup too. For my lathes setup, which has an encoder I designed & built for feedback, I used the cnc4pc C41 board, but its not fast enough to do servo controls without pulling that pair of 10uf caps and replacing them with .1 paper/mylar caps. Thats good in any event I think as electrolytic caps in such low voltage circuits are generally a failure time bomb with a 6 year or less fuse. I am a C.E.T. FWTW. Lots of experience with that in my pre- retired life. I haven't yet wired the lathe up for reversing the spindle, and with linuxcnc's G76 thread cutting cycle, I have not encountered a situation where I needed it yet. I also found that it was needed to add at least a 10k "buildout" resistor between the C41 output, and the connection in the motor controller board where the arm of the old front panel speed control pot was connected, else the control was so non-linear the PID couldn't be tuned. The end result is that I have cut some downright "purty" threads on that 7x12 toy lathe. > - and finally connect the emrgency button on the BF30 with LinuxCNC. I assume that kills spindle power, similar to my toy lathe, but since its line powered, I would translate that power on/off signal with a relay, so it you hit to e-stop there, LCNC would also see an e-stop in a few milliseconds, which /should/ be fast enough to stop it from breaking mills. All LCNC needs is the contact closure of the back side of an spdt relay when the relay releases. > Has any body done this for this specific machine before, or has anybody > a simple schema for a pwm converter to 5V? > While I've not had a need to go that low, most such circuits seem to be geared toward 0 to 10 volt control signals, I know the C41 can be turned down that far, and I believe the PMDX-106 can be also. The only gotcha in the PMDX-106 I know of, is one I just found recently as I was using the G38 probing moved to locate the workpiece, using the mill turning in reverse as the touch probe, and I was shutting it off when the touch had been detected, but LCNC was killing the reversing relay while the PWMGen was still putting out a small signal, and that control module was seeing what it thought was a motor turning backwards when it was supposed to be turning fwd. And its a very stiff controller, capable of blowing its fuse before you can hear the motor slowing. That, once analyzed, was predictable that the stop would be pretty brutal, with the ammeter showing as high as 1.5 amps as it stopped in just a fraction of a turn from 200 rpm. Solution was a hal module to hold the reverse true for half a second on reception of the M5 stop signal. I likely have the relays improperly sequenced but haven't found my round tuit to fix that yet. :) My spindle stops are pretty fast as is because I drop a 20 ohm resistor across the motor when it should be stopped, so 2500 rpm > 0 rpm is about 1.5 seconds. Very little coasting. Using the C41 was cheaper, but far more trouble to make work well. > Thank you for any hint or help. > > Regards Peter > > > ------------------------------------------------------------------------ > ------ Try New Relic Now & We'll Send You this Cool Shirt > New Relic is the only SaaS-based application performance monitoring > service that delivers powerful full stack analytics. Optimize and > monitor your browser, app, & servers with just a few lines of code. Try > New Relic and get this awesome Nerd Life shirt! > http://p.sf.net/sfu/newrelic_d2d_apr > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users 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> : The hierarchy is excessive. So is the anarchy. :-) -- Larry Wall in <199705101952.maa00...@wall.org> A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_apr _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
