On Sun, 6 May 2012 21:52:21 -0400, you wrote:
>> > What is the best practice to establish the X zero on a lathe? I am >> > making a test cut, measuring it and dividing that by half to enter in >> > a Touch Off. That's the only way to accurately do it. >> If you have a quick-change toolpost, > >I do. >> you should be able to set up X and >> Z offsets for each tool in the tool table. > >That would require I get at least 3 or 4 more QC toolholders. But then I >am reminded that the QC post must be rotated in order to present the tool >to the work at the correct angle, which is only as repeatable as eyeballs >can make it. OTOH, I do need more toolholders. I could make a setting >tool that would fix the reach out of each tool pretty consistent. But >before I tie a few hundred more up in holders for this flimsy post, my >first inclination is to ditch the whole compound slide since linuxcnc can >handle that rather nicely, and put a bigger, far more rigid QC post >directly on the X cross-slide. Something made out of real steel as opposed >to the crappy, flexible alu this QC is made out of. I generally use my QC toolpost, I never move it's position once set. Like you suggest it's mounted directly to the saddle. It has two dovetails, one for Z axis orientated tools and one for X. I have 14 tool holders, most of which have a specific tool permanently mounted. The holders are numbered so I can remember which tool is which <G>. You'll find it will be rare to use more than four or five tools on over 90% of turning jobs. I also have an 8 position Enco type auto tool changer that I made, but haven't managed to get that to work with LinuxCNC. I gave up after days of hal editing. >The thought also crosses my mind to mount a microswitch for homing that >could be dropped into a locator on the carriage, but that would require a >touchbar 3 inches long that was exactly on axis. The alignment to keep it >on axis while allowing it to swing out of the way, or be "unplugged" to get >it out of the way would be fairly stringent though > >As for z axis, I generally pick an arbitrary stickout suitable for the job >and locate on the end of it, writing the gcode to run negative from there. >> Then, you leave the tool >> offsets on >> all the time. X=0 is the center of the part, Z=0 puts the tool on the >> chuck (or wherever you decide to have the Z zero). >> >> > Has anyone else come up with a better idea that might be more usable? No - My tool 1 is my reference and touch off tool, it has offsets of 0, 0, all other tools are referenced to that - it's a CNMG type and gets used for roughing, facing and finishing. That gets touched against the face of the job, or I take a facing cut then Z zero'd and continue. >Whoever has the touch-off code box, it sure would be nice if when you >called it up, it displayed the current value separate the input box. As >is, I have to write it down, so I know where I am if I only need to adjust >it say 0.0027 from where its at to get it exactly the right size for the >next pass. That would be almost as handy as bottled beer. :) Wear offsets would do the same thing. They are easy to use. You set your tools initially with new inserts and should never need to play about with tool tables again. All you do is enter the correction value. Say you find you're turning 1 thou over diameter, you enter X -0.001 in the wear offset dro and it corrects the X tool offset. It doesn't alter the original offset, it's an additional field in the tool table and automatically takes into account if G7 or G8 Diameter or Radius mode is in use. Steve Blackmore -- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
