On Monday 03 September 2018 16:35:01 Gene Heskett wrote: > On Monday 03 September 2018 10:20:09 Les Newell wrote: > > I would first stick a hal meter on bwX0 to see what lincurve is > > actually doing. > > At the moment, zip. > > > Using offsets like this can be troublesome. I did something similar > > on my lathe for a while and always had homing issues. The problem is > > that your Z position suddenly changes when it finds the home switch > > so the offset on X suddenly changes, causing a following error. > > That agrees with my diagnosis. But it will rule out useing the offset > in X to tell it the switch is 5" or more from the centerline, so touch > offs WILL be required before the dro is within an inch of the real > diameter. > > But by using a limit3 to limit the correction speed, I might be able > to get away with it. > > Humm, sounds like a limit3 set gawdawful slow, between lincurve.out > and offset.in might be usefull.
Actually, a better place might be between Z-fb and lincurve.in essentially putting a shock absorber between Z-pos-fb and lincurve in, with say a delay of say 1/2 second to propagate thru the limit3. No [joint].0.OFFSET allowed to be used. else a following error as the home switch closes resetting everything. That, at the speeds of carving metal, would be essentially instant in terms of applying a ramp between lincurve setpoints that might move 3 thou in x as z moves 2.25". There seems to be a rather considerable wear right in front of the chuck, which returns to a gradual move of maybe 5 thou in the next 20" slowly because the tail stock isn't perfectly aligned. Unfortunately, even if I don't diddle the tailstock latterally, the choice of centers throws an unk error because out of 2 deads and 3 lives, only one old worn dead seems to be well aligned with the tailstock barrels center. And two of my lives can move the point in a 1/16" diameter circle just by rotating their mt3 in the barrel. Ebay crap, looking for a good one. So I need to develop a method of setting their rotation in the barrel to get a consistent, minimum error. And marking them with a sign that one girl I knew when living in Carroll NB in the '70's had on her t-shirt, a sign that said "this side up". She once described her mammary's as two aspirins on an ironing board. But thats yet another, probably boring chapter in the gene vs sheldon story. Silly Q: How would I slow this same correction for a [joint].n.home_offset, thereby allowing an x home switch 5.75" out to actually set "home", parked 50 thou off the switch to be displayed as 5.45" or radius in the dro. Currently is reading just a few thou, and has to be corrected with a touch-off. > At the normal speed of Z, the > correction is likely less than a thou per second. So X ought to be > able to keep up. Something in the range of 3 or 4 thou is all the > correction it would need according to the measurements I've made so > far. > > LCNC can also use a file, but only in the same axis to comp for screw > thread errors, so its helpless in this case. Bed wear is an X > correction based on Z measurement. Does not correct for tool height of > coarse, only for the tilt inward and outward created by uneven bed > wear of the front and rear bed rails. > > > This movement > > also does not obey any maximum acceleration limits. The moveoff > > component tries to work around some of these issues as it obeys > > acceleration and speed limits but you may still have homing issues. > > So I'll try the limit3 just to keep the corrections within the X > motion envelope. > > But it will be a day, maybe 2 before I get back to this if WHAW won't > come up at sunrise tomorrow, and then I put two cans of R-134A in my > pickups AC this morning, which may have been half a can too much, so > I'm going to let the pro's check it out. At one can it was making > cooler air, but still in the 80's, nowhere the 50's I expected. Gages > said I had room for some more, but that killed any cooling as its now > cycling the compressor. > > Some mornings its just not worth it to gnaw thru the straps and get > up to pee... Too many years (83) on this carcass. > > > Thanks Les. -- 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> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
