On 2014-06-29 18:23, Gene Heskett wrote: > On Sunday 29 June 2014 09:47:33 Marius Liebenberg did opine > And Gene did reply: >> On 2014-06-29 14:41, Gene Heskett wrote: >>> On Sunday 29 June 2014 06:46:14 Marius Liebenberg did opine >>> >>> And Gene did reply: >>>> I am finding it necessary to reconfigure my lathe as I cannot >>>> operate it properly as I have it setup now. I need some advice >>>> please. >>>> >>>> What I have. >>>> Mesa 5125 with a Mesa 7i76 >>> Good I believe. >>> >>>> Photo interrupter spindle speed counter >>> This will need to be replaced with a full A/B/X* encoder, which will >>> give you within its capability, all the spindle position and >>> direction info you'll need, and I believe the 5i25/7i76 handles it. >>> >>>> AC motor without VFD >>> While gear changing in the belts or back gear etc can be done, it >>> will need also, a means of stopping it, such as throwing a DC >>> current thru it to bring it to a near halt fairly quickly, (called >>> suicide braking in some circles) and a method in relays to run it in >>> both directions if you want to do rigid tapping, which will require >>> the full A/B/Z encoder anyway. I am using a treadmill dc motor, and >>> a pile of ice cube relays to achieve that control with a single >>> quadrant controller. And my hal file may be the longest one, its >>> close to 300 LOC as all those direction & timing related things are >>> in it. I just yesterday, drilled and threaded 4, 1/2" bits of cold >>> roll rod to 6x1mm for the motor mount standoffs using a peck loop >>> using g33.1, where each time thru the loop it drove the tap 1/2 turn >>> deeper until I was out of tap. I could then blow the tap clean on >>> the backstroke, and apply a drop of cutting fluid. >> Ok so it looks like a VFD with a brake resistor on a 3Phase Ac motor >> will have to be used. >> >> The motor is only 0.55Kw (0.73Hp) I will fit a 2Kw motor and leave the >> belts set to a happy middle of the road selection to get speed and >> torque > Sounds like a fairly small machine then, table topper or such. It similar to the Lathe Master (10x22). I have it mounted on a stand that takes to men to shuffle move it. My wife says I should have been born in Texas. Always bigger and better.
As I said, I will fit a bigger motor and because I only paid about $850 for the lathe new, I can afford to add some decent stuff. > With the PID module in your hal file properly setup, it should work at > most any belt ratio as long as your code doesn't ask for more than it can > do at that belt setting. > > Mine handles a 2/1 backgear switch without any problems other than > forgetting which gear its in and typing an s700 for speed when in low > gear. Runs the motor up to about 12K rpm's :) Presently, because there > is little use for more than 1k rpms when cutting unless you have coolant > which I do not have, my max speed is set to about 950 rpm. Or about 550 > in low gear. > > I need to get in the habit of leaving it in high gear. > > The VFD and matching motor will of course allow better control, > particularly at reversal time, but thats getting into bigger machinery > than I have room for or could afford, although I've been drooling over the > 10x30 Bolton which is the largest variable speed one they make. But then > I start considering what all new ball screws, tooling, chucks etc would > cost before it makes its first pound of swarf and go get another cuppa to > help me come to my senses. I figure around 6 to 7G's by the time its > really ready to do work. For that, there's an old (100+ years) 15x96 > Porter I can have for a $500 bill, sitting out in the weather (but all the > knobs work, and a motor isn't on it, and only rudimentary motor mounts, 4 > speed flat belt drive) at one of the local junk shops. But I haven't been > interested enough in building another small yard building to house it to > even check what a 1.25" by 110" or more ball screw would cost. I have > visions of somewhere north of $1000 for one that big, and out here in the > puckerbrush of WV, which trucking company is going to bend it for me. So > far they've been pretty good at bending Nook stuff in 3 foot sticks. :( > > Cheers, Gene Heskett -- Regards /Groete Marius D. Liebenberg +27 82 698 3251 +27 12 743 6064 QQ 1767394877 ------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
