On Monday, May 07, 2012 09:20:34 AM Steve Blackmore did opine: > 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. > And this is a case of Touch Off, when used in a lathe config, needs to be told the upcoming entry should be applied to the diameter, not the radii, removing the need for paper & stick, or a pocket calc, or better yet, a session of kcalc, with supports copy/paste going both ways, just to set it correctly. But usage problem #2 is that you have to write it down because if the next cut & measure says it still needs tweaked another thou, because Touch Off doesn't display the current setting, but defaults to 0.0. That of course makes it easy to cancel a Touch Off, but I find in my usage, I need to just edit it another thou or so. Not knowing where its at without scribbling on the bench or a small notepad makes its use quite mistake prone for me. (which scribble is the last one?) Am I the only one who sees it that way?
> >> 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. You must have tools that obviate the need to turn the post in order to present the tool to the work at a std angle. My indexable kit, a Glanze mini kit has left & right cut tools, but to fully use them I'd need to have a dedicated holder per tool. That's coming in due time, but first that rubber compound slide has got to go. This whole QC setup, being made of alu, is one of the mistakes I made, trying to make this toy work. The only reason I use it most of the time is because the OEM tool holder always needs a shim I don't have under the tool, it isn't adjustable for center height. PIMA. I am hoping I can find a QC base that would be adaptable to the circular insert in the cross slider that allows the compound angle to be changed, so as to maintain the ability to rotate the post, but I suspect most are center bolt mounted. I could replace that disk in the cross slider with one with a single center tapped hole to fit the QC's mounting bolt. I have some steel from hell I could make it from too, something that would give me much stronger threads. (I've already pulled the toolpost thread out of the compound once) I think its from hell as it sure plays hell with carbide tooling anyway. ;-) > 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 crossed my mind of trying to adapt the tailpost type tool changer to a carriage mount, but so far that is just a thought. ;-) > >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 An acronym I'm not familiar with, but I expect google works ... > 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. I'll have to look at those 2 commands! TBT, I'm not sure ATM which mode its running in. Maybe that would fix my /2 problems with touchoff... A quick run from here says it has G8 in effect. That also says the hal file I attacked with a whole set of ginsu knives last night is at least error free enough it will run! Amazing. Maybe I'll get this hal thing figured out yet. :) > Steve Blackmore Thanks Steve. 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> A woman did what a woman had to, the best way she knew how. To do more was impossible, to do less, unthinkable. -- Dirisha, "The Man Who Never Missed" ------------------------------------------------------------------------------ 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
