On Monday 24 November 2014 18:54:46 andy pugh did opine And Gene did reply: > On 24 November 2014 at 23:41, Leonardo Marsaglia > > <[email protected]> wrote: > > Because in my head I'm picturing the rise and fall signals and I'm > > worried about where the zero rising point will fall, but may be it's > > not that important. > > The delay is likely to be consistent, so as long as the spindle speed > stays the same (and it normally does in threading) then you won't > notice.
This is quite true of the G76 threading cycle, but new bees need to be aware that if you change the spindle speed drastically while its cutting, the resultant thread will slide sideways enough to wreck it, so you should let it run to completion at whatever spindle speed you started with. This is also NOT true of the rigid tapping cycle G33.1, so that should be run moderately slow, dependent on the rotating mass and available PSU power available to reverse the spindle. Where it can be slide sideways is at the point, out of the work where it stops and waits for the next index pulse where it accelerates to match the spindle speed, lagging the spindle by a few degrees, but its then locked to the spindle. But that is normally done at a slow enough spindle speed that its only a few degrees of offset and as long as the spindle speed is not changed drastically, its kewl & consistent. Because the reversal at the end of the stroke is done at whatever accel limits are set in the ini file, and higher speeds mean deeper feeds before it can get stopped and turned around, I generally don't spin at more than 250 revs. By dropping to 120 revs, the overshoot is less than a full turn with my lashup, but each machine is its own law enforcement. A 14" chuck and a 5 horse motor will not be able to duplicate that. Way underpowered for the rotating mass. To put that in perspective, mine is a toy, a 7x12, with a 5" 4 jaw that weighs several pounds, has a 1HP treadmill driving the spindle, geared down about 3/1, controlled by one of Jon's servo drivers and powered at about 107 volts dc max from a psu that can make around 2.5kw IACS, 1.5kw CCS. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
