On Monday 29 April 2013 01:59:23 Cecil Thomas did opine: > I recently was given a 1953 Monarch 10EE "basic Model" lathe. It is > the Ward Leonard motor generator type so no electronics to deal with. > The basic model has no lead screw and no gearing for screw cutting. > There is also no taper attachment. It does have carriage and cross > slide power feeds. > > I have installed a rotary phase converter and have the lathe powered > up and it is completely functional. The lack of thread cutting begs > for the lathe to be converted to CNC. I have successfully converted > a 7x10 and a jet 9 x 20 and am comfortable with the project.
> My only > real concern is going to be integrating spindle speed control because > the existing control utilizes two huge rheostats to control the drive > motor field and the generator field. I might just lash up a servo or > stepper with a belt to the control knob. The (lack of) speed of response in all that mechanical doings might make that less than successful. But I am not familiar with the Ward Leonard motor generator either. It sounds as if its a 3 phase AC motor turning a DC generator which in turn powers a DC motor that actually drives the spindle? For those DC controls, I'd think it would be a lot more power efficient to toss the rheostats in favor of pwm controlled hexfet power devices that linuxcnc can control directly by using opto-isolation techniques which would give 10 to 1000 times faster control, with perhaps 1/100th (or less) of the power losses the rheostats will have, directly from a quadrature sensing disk and opto-interrupter detection of not just spindle speed, but spindle position in real time as it rotates. Just throwing out alternate, more efficient & faster control ideas. My $0.02 IOW. The general idea is that of having a PWM signal from linuxcnc turn the power on fully for a period of time dependent on a comparison of the set speed with the real speed, and turning it off and shorting the winding so the current continues to flow, but will decay until its not enough. Do this 1,000 times or more a second and you can have an extremely rigid speed control because if the encoder feedback says its 3 degrees behind where its supposed to be, it will hit it harder until that position error is effectively nulled out. Real time control adjustment at every encoder transition. I only have a 50 slot disk on my 7x12, no room for any more so I get a fresh error reading 200 times a revolution, but I also have a PWM to 0-10 volt converter in the path which slows the control, a lot. But I can start it at 200 rpm, wrap a leather belt around a 5" chuck and blow a fuse before there is a detectable by ear speed change. > Has anyone converted a 10EE to CNC? > > Cecil 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> I don't want a pickle, I just wanna ride on my motorsickle. And I don't want to die, I just want to ride on my motorcy. Cle. -- Arlo Guthrie 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
