You do know you can do math in the touch-off window?
so 5.345/2 or 5.345*2 or whatever.
On Mon, 7 May 2012 10:16:11 -0400
gene heskett <gheskett@...> wrote:
> 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>
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