On Thursday 31 July 2014 08:15:34 Claude Froidevaux did opine And Gene did reply: > Le 31.07.2014 12:10, Gene Heskett a écrit : > > Basically, I want something that will overwrite any existing offsets, > > as opposed to adding to the existing ones at the instant of the call. > > Looking it up and reading it on that machine, that line about > > "calculated" is the confusing part. > > IMHO, G10 L20 is not what you want .. (it's working a bit like G92) > > I do it by removing current value by reading the variable and > substracting it: > > G54 Z is stored into variable 5223. > > Something like > > G10 L2 P1 Z[#5063 -#5223] shall do the trick
And I assume I can do the same thing with the G56 data, after I lookup and find where that existing Z is kept. I am doing something similar in my holefinder code. The #100-#101-#102 data is calculated by moving the G38.2 results into local vars, searching for the 4 contact points a conical probe (or an engraving bit turning backwards as it first descends to make contact & establish a "working height" for its measurements, then raises about 10 thou, and searches both directions for contact, establishing the exact center of a piece of .125" OD brass pipe glued into the pallet so the pipes offset, also found by electrical contact to the work to establish the true X and y zero points. So the pipes offsets from the pallet pocket are known and hard coded into the holefinder code. This sounds as if its exactly what I should be doing for z height corrections. But first, redo the pallet, again. I noted its not perfectly flat yet even after redoing it with a bit longer pocket a couple thou deeper too, to make room for some led adjusting pots which I have to offset the eagle pdb2gcode for by adding or subtracting that extra length offset. Grabbing the x table yesterday, I see I need to snug up the gibs as I can feel the play again which might explain the .0005" cutting depth error I saw, like the pcb is sagging in the middle. I couldn't do that 2 weeks ago. This toy doesn't have a ready means to lube the X ways and I'm considering burying a pair of snap cap oilers in the table just to get some central oil into it. I did put some weed eater tubing into the X & Y nut holders, from a small brass manifold mounted on the side of the post. So I can give them a drink of vactra weekly when its being used. A friend of mine keeps accusing me of trying to make a silk purse out of a sow's ear. He's right of course, but I'd druther it wasn't so obvious to the frogs. ;-) With the ball screws in the x&y, the holefinder repeatability is someplace in the 4th digit right of the decimal point in inch mode. So the "sows ear" machine is gradually doing better... Thank you very much for the hint, Claude. All this sudden pcb carving BS is because the encoder on my lathe, which was liberally wire wrap patched due to the fragility of the .005" wide traces it used to make things fit, just up & died after changing two resistors, trying to get a perfect 50% duty cycle out of it, so I have to make a new board, and the mill has been modified since that code ran in February of 2013 to make it the first time. Its now about 10x more accurate at z depths after putting in some U shaped brackets on each side of the head casting, carrying ball bearings that make the sleds wheelbase about 2.5x longer, and stopping the stiction that was making it move in 5 to 10 thou jumps when moving at slower carving speeds. Progress! But it obsoletes some of my old code too. This board would be a hell of a lot easier to build if I just sent it out so I'd get plated thru holes back. :) But I'm cheap, with more time than money. ;-) 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 ------------------------------------------------------------------------------ Infragistics Professional Build stunning WinForms apps today! Reboot your WinForms applications with our WinForms controls. Build a bridge from your legacy apps to the future. http://pubads.g.doubleclick.net/gampad/clk?id=153845071&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
