On Monday 16 June 2014 12:37:06 chris did opine And Gene did reply: > Hello to all CNC-Linux users! i really enjoy it to get in this > community :) I just join this list, so I hope i doing it still right > to reply to this massage... (my english is not so perfect..) > > My question on limit-switch is, that i want to use it too as a probe > test, so i can tune my stepper-motors a bit. > In this case i can be sure, that i don't lose any steps. So I did use > another switch that do switch all limit switches to the > probetest-digital-input of the parport. But i got got an error > something like "probe hit while moving" > does anyone have some experience with this case? how change the > debounce time on the digital-inputs? > Chris Not perhaps a perfect solution, but when probing, one normally does a fast approach at .5 ipm or so, then backs away a couple thou and does the approach at creep, .05 ipm, speed. In several cases I have found that I must set a backlash for a thou or so greater than measured so that when the back away move is executed, the switch was actually opened. It appears the system doesn't check switch status during the back away move.
This may not be the correct way to do it, so I'll let the authors answer as to how it is supposed to be done. I'd welcome a better way myself. I have also used the global position cache in the #5000 region that lcnc saves on contact, to do a back away move that I know will positively re- open the switch. And because some of my probing, like for the mechanical middle of a test/registration hole in a pcb, makes use of a spinning wire made from a needle threader that occupies a cone shape while spinning at say 200 rpms, with very fleeting contact, I have a .1 uf tantulum capacitor across the probe line to ground, which has the effect of doing a sample/hold on the contact for long enough for it to be caught by the base_thread driven probe. That improved my hole finding accuracy by a few thou. For that, I usually use a bit of brass piping sunk into the insulated pcb pallet which has a known offset from the corner of the pcb as a contact for the probing. I suspect others have their own "bag of tricks" for such use. lcnc gives you at least 50 ways to get the job done, or hang yourself. :) 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 ------------------------------------------------------------------------------ HPCC Systems Open Source Big Data Platform from LexisNexis Risk Solutions Find What Matters Most in Your Big Data with HPCC Systems Open Source. Fast. Scalable. Simple. Ideal for Dirty Data. Leverages Graph Analysis for Fast Processing & Easy Data Exploration http://p.sf.net/sfu/hpccsystems _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
