> > From what I understand you're talking about a normal parallel lathe so here > are my thoughts: Yes. And thank you. > > > The Z axis is more interesting. Before homing I imagine the tail stock > > has to be loosened and moved all the way to the right as far away from the > > headstock to ensure finding a home switch. Or a home switch could be > > somewhere in the middle but then which direction to search? > > > > I think the safest setup in this case (given your Z axis can crash with > the tailstock if you forget to move it all the way to the right) will be > having the home switch towards the chuck side (with a proper > independent limit switch right at the left of the home switch to avoid > crashes when homing). This way you can set up your homing sequence to first > home the X axis to move it to a safe place and then home the Z axis towards > the chuck.
I'm guessing you are suggesting something like what Gene was that the home switch isn't at the end of travel but somewhere else and once activated never goes inactive in that same direction. So if you start a home sequence and the switch is ON you know you have to go to the right until it goes OFF. It can't over travel past the OFF position and go ON again. That approach lets the Home Switch be pretty well anywhere. Unless the limit switch is movable it's useless. My carriage can go much further to the left to turn near the part held in the 5C collet than it can with the part held in the 3-Jaw. So a crash into the spinning 3-Jaw can happen without ever touching the limit. And if the limit does prevent that one can't turn a part close to the collet. > > How does one determine, with that tool tip, where the lathe centerline is > > and set that so G54 X is 0.000? > > > > I think you're asking about tool setting. If you have tool fixtures that > ensure that whenever you change your tool you get the exact same tool > position then it's just like a CNC turret. You just take a skim cut on the > diameter (or maybe use some fine paper to gauge the tool against the > workpiece) and then measure and input the diameter (or radius depending if > you're in G7 or G8) in the touch off popup. > Thanks. I'm going to have to study that a bit further. I understand that the machine coordinate for x at the home switch is 0.000. And measuring the tool tip relative to how it mounts into the AXA holder can be done creating an offset from the home switch.v Now each time the tool holder +tool is put into the AXA the distance from the tool table is offset from that home position and LCNC knows where the tip and can turn a diameter. Theoretically. However as soon as the holder is pivoted even slightly the distance of the tool tip relative to the home switch changes. And it changes differently depending on how far the tool protrudes out of the AXA holder right? So the tool measurements are only useful with the AXA in one position and that can change really easily in the home shop. We're not talking a commercial production operation where the setup is the same over a long period of time. I suppose if you can touch of or measure the new position of the tool tip you can then use simple trig to determine the angle that the AXA holder has pivoted. Unless it also slid in the T-Slot which now moves it in more than one dimension. Doe my explanation make sense? A small shop lathe where the operator can shift the tool bit around relative to the X home switch and even on the carriage relative to the Z home switch suggest a tool table for a LCNC lathe is virtually impossible. So I can manually turn that shaft. Leave the X axis where it is and measure the diameter; say exactly 1.000". Then click on the "Touch Off" on the display and enter half the diameter (0.5") for the offset. Now a request to move the X to 0.480" to do a 0.020" deep pass should work right? But the tool table and for that matter the home switch and machine coordinate system is pretty well useless. Or have I missed something? John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
