On Tuesday, March 13, 2012 07:10:33 AM Kirk Wallace did opine: > On Mon, 2012-03-12 at 23:25 -0400, gene heskett wrote: > > Hi all; > > > > At some point a few days down the log, I will need to see about > > putting one of Arturo Duncan's C41 spindle interfaces into this > > lathe. > > > > Has this been done before, or am I essentially wielding my own > > machette in this teeny little weed patch? > > > > What I've been able to find with google is essentially zilch. > > > > Cheers, Gene > > This lathe? > http://coyoteden.dyndns-free.com:85/gene/emc/slides/slide_lathe1.jpg > > If the present control is with a potentiometer, my vote would be to > start with replacing the pot with an opto-isolator on the pot V+ and > wiper connection. Then feed the opto input with a parallel port pin and > software PWM or PDM. If you have a faster hardware signal generator > (FPGA thingy), that would be even better. I use another pair of > opto-isolators for Forward and Reverse.
The cnc4pc/C41 board has that, and can replace the pot totally. It also has a relay which will replace the fault/reset switch on the back of the pot. But this is the slightly later board with the daughter board integrated into it. I have just spent 2 hours reading the various threads without finding a link that puts labels on those 3 controls as I need to adjust the fwd speed, it runs at about 30 rpm minimum with no torque. And takes about 20% of the pots rotation to start turning in reverse. Out of balance electronically. Complicating things is the 4 pole center off reversing switch that I'll need to make into a DPDT relay which the 2nd relay on the C41 will control. 4pdt? I wonder what the other 2 poles are doing, says he? I can't personally see the need for more than a DPDT there as all. I may do as I did on the mill since the spinning chuck is a lot bigger flywheel to stop and reverse in a reasonable time. There I have the back side contacts of the run relay loaded with a 10 ohm 20 watt resistor, so when I or the computer turns off the mills spindle, its stopped from full speed in a little over 1 second flat. The same idea on the lathe should stop it in 2 or 3 seconds even with a 5" 3 jaw chuck installed. So unless someone knows different, I am going to treat it as a unidirectional speed control, with an added reversing relay between it and the motor. However I'd like to find out what those 3 adjustment pots do because in addition to the fwd min speed isn't zero problem, it is not a very 'stiff' drive. Incapable of blowing a fuse even if stalled by a dug in tool from 600 rpms. The mills controller is so stiff I had to put an ammeter in circuit to see how hard its working, there is no change in the rpms or the sound from .2 amps idling to 450 rpms to over 1.5 amps cutting load and I was blowing $20 worth of 2A fuses a day. The ammeter was self defense. In the back of my mind is the thought of buying a spare controller for the mill, replacing its big hexfet with a 10x heavier rated one like I did in the mill, and using it with that 2x bigger lathe motor. I think it would work just fine & likely several times stiffer a control than this overly complex controller seems able to do. 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> I never pray before meals -- my mom's a good cook. ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
