Hi all; I have a very small error, perhaps .010" in the top vs bottom hole & pattern placements.
Unless someone can convince me that pcb2gcode has a built in error in its Y calc's for the bottom of the board, the error is mine, darnit. Background: The eagle .brd file I was sent is arranged such that the board is bigger in Y then in X. However, in building a pallet to hold the board I much prefer to have the board pattern laying long ways with the X axis. So, I wrote, and it has worked fairly well, for several projects based on the first pallet I made for the lathes spindle encoder a holefinder routine to establish a known location on the pallet, just off the upper left corner of the board, a short piece of 1/8" brass tubing, superglued in place and connected the the LCNC probe input pin. Then I made, from a sewing needle threader, a probe I can put in a 1/8" collet, with the wire shaped like a sharp speer. I have a .1 uf cap on the probe circuit which captures and holds any momentary contact the probe wire makes to the inside of the mouth of the tubing, holding it long enough for LCNC to grab it. The facilitate LCNC seeing the probe wire as a perfect cone, the spindle is running about 1800 rpm while this probing is going on. Basically it lowers the spinning wire into the hole until first contact is detected, then raises the spindle 20 thou for clearance, then moves first the x, capturing #5061 into 2 vars as it moves to detect the tubing, first left, then right. It adds those two, and divides by 2, then runs x to the mathematical center. Then it does the same with the Y axis, captureing #5062 into fronty and backy vars, does the same /2 and runs the mills Y to that center. Once its done that, it applies the detected offsets to the G55 and G56 maps, which are then used by the rest of the code depending on whether its for the top (G55) or bottom (G56) of the board. The bottom however has an offset added such that running the bot.drill file should result in holes drilled halfway through the board that meet in the middle. But, both G55 and G56 are also rotated with an R270 at the end of the G10 L2 P# statement in this code. What I am getting when I drill 5 thou into the board running the two drill files from pcb2gcode shows a dead on registration has been achieved with the offset as applied to only the G56 map. The board is being flipped along the x axis, so the same end of the board is always wedged via the hold-down screws against the left side of the milled pocket, so I can't see that as a source of error here. But, I have an offset of perhaps .012" in the drilled Y positions after the 270 rotation rotation to convert it to my mills real X axis. Could this be an artifact of a small error in the fudgex and fudgey vars at the top of the file that you can see on my web page in the Genes-os9-stf/LCNC link? These are the actual locations of this brass tube, with reference to the assumption that as I see it on the mills table, of the exact 0.0, 0.0 upper left corner of the pallet's board pocket. Supposedly. On the previous pallet, I established a 0,0 location then moved .2 left and .1 below and drilled the hole for the brass contact pipe, this time I got ahead of myself and milled the pocket, then installed the pipe, unforch after the 0,0 had been lost due to re-homing the machine the next day. Because there is nothing to reference at that location since its an inside corner, and I ran the mill making that pocket, out at the correct angle to serve as clearance for the sharp corner of the board, its not something I can measure and easily verify. I am ATM, fresh out of ideas, and somewhat confused in trying to trace the error because I am using the G55 and G56 mapping to rotate the pattern as it is seen on the mills table. So if some kind soul could look at this "tholefinder.ngc" file at the above link & suggest how to proceed in removing this error, I'd be most appreciative. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> I put up my thumb... and it blotted out the planet Earth. -- Neil Armstrong A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Get 100% visibility into Java/.NET code with AppDynamics Lite! It's a free troubleshooting tool designed for production. Get down to code-level detail for bottlenecks, with <2% overhead. Download for free and get started troubleshooting in minutes. http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
