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Offline MarkC

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Mach Lathe questions/problems
« on: June 15, 2007, 10:26:45 PM »
Hi guys & girls,
Me again. I'm having problems using lathe. I've worked most of the problems out myself, changing my post, but 3 things I still can't figure out. I'm hoping a lathe guru can help me out. I've learned a lot lately about what to do and not do and I'd like to do a FAQ or other posting where all I've learned is in one place. I've seen that lathe is not near as popular as mill and documentation is spotty
So on to the questions:
1st: when I send the axes home, they do not "zero out". I have set everything I can find to make them do that. I set x & z zero at home and no tool (T0) active when starting Mach
2nd: The offsets do not repeat after homing the axes, so if I have a G28.1 at the end of the program, I will need to touch off again; the amount they are off is different than the # on the screen when homed before I set it to zero.
3rd: Is there a way to just send the axes home without "any other" move taking place? G28.1 X0 takes x to X0 at rapid then home at a slower pace, G28 X0 goes to program X zero. On a Fanuc G91 G28 x0 goes straight to X0. , here it didn't do that, but I don't remember exactly what it did. My brain is frazzled.

I'm using the latest version of Mach3
Any help is appreciated

Thanks
Mark
Mark

Offline DAlgie

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Re: Mach Lathe questions/problems
« Reply #1 on: June 16, 2007, 05:42:51 PM »
The lathe offsets are tricky for sure, but it's really simple once you have had experience with it. I don't use any G code homing or work offsets in the program. I start the machine up and send both axis to home, this sets the machine position to the last set tool position. Unlike a mill, there is really only one work offset change needed, the Z axis position, that will depend on how long your part needs to be to be able to part it off when it's finished, how much is sticking out of the chuck. Use persistant tool offsets and the control will start with the last used tool. I set home with the "Set home" X and Z buttons first. Just above that is the work offset display, put Z 0.00 in the Z offset and the diameter of the piece of stock you will set your tools to in the X offset display. Put in tool 1, and set that in the tool number box as well, and jog up to the face of the material, after facing it off, and touch off on it. Without moving the tool, go to the tool offsets page and hit "Touch Z", making sure that the control has tool 1 loaded. Make sure the tool tip radius is set then as well. Go back to the jog page and do the same for the X axis. If your chuck has any perceptible runout you will need to turn a small amount off the diameter with jog mode then measure the diameter and load the number in the work offset display, before setting the X axis. Go through and change tools on the display and do the same for another, assuming you DO have a quick change toolpost. If you don't, you will have a hard time trying to do much, you have to constantly reset tools for anything you do. This is probably as clear as mud right now, ask more and I will tell more if I can.
                   DaveA.
« Last Edit: June 16, 2007, 05:45:16 PM by DAlgie »

Offline MarkC

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Re: Mach Lathe questions/problems
« Reply #2 on: June 16, 2007, 07:30:59 PM »
Thank you for the reply Dave.  ;D
I kinda figured it all out myself today. I just locked myself in the garage and tried stuff.
I think my main problem was, I was using the"Part Zero X" and "Part Zero Z" buttons because they seemed to do what I wanted.  Not sure what the difference is between them and the "Touch" buttons, because they both set the DRO to the value in the part zeroing DRO'S. I suspect it works if you're only using one tool, or could this be how to change the G54 offset? Not sure. It's different for sure than what I'm used to, Fanuc controls.
I do have a quick change toolpost, so I want to use this feature.
For some reason, the DRO'S now now set to zero at home with no tool offset active; suspect that maybe I didn't restart Mach after changing the homing values.
Still not sure about sending it home after program is over. I'll experiment.
When I'm all done, I'll post a thread or FAQ about how to do things, because, like I've said, lathe stuff is kinda sparse

Thanks again
Mark
Mark

Offline DAlgie

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Re: Mach Lathe questions/problems
« Reply #3 on: June 16, 2007, 08:15:13 PM »
I guess I don't send it home, or to any G offset value, I just avoid that, I'm used to  Fanuc as well with no G54- 58 work offsets like the mills do. My company's OT control used no work offset really. Mach lathe has too many options for lathe I guess, which tends to confuse people. I use the Mach silverblue screen, very very nice for lathe, never have used the original one. After you set a tool up, I pull the stock out of the chuck and use the MDI line, G0 X1 Z0 and make sure it goes where you think it should. I have never used a home position on a lathe, with some strange shaped parts you can get in trouble with a fixed home position so don't reccomend it.
Re: Mach Lathe questions/problems
« Reply #4 on: June 17, 2007, 12:11:16 AM »
Here is my .005 cents and the way i run my lathe
T0101 is the master all other tools are referenced to this one
T0000 and T0101 should Never has any offset or wear
I program everything positive with a front toolpost

Manually take a face cut leave z position alone, type in part Z Dro value, zero Z axis dro and then press part Z axis zero
manually take a horizontal cut leave X axies alone, measure and divide by 2, input the result in the Part X axis Dro, Zero X Axis DRO, then press Part X axis Zero.

all other tools now can be set up reference T0101  using part DRO's and will follow Tool 0101

Thats basiclly what the manuals says
then i use the part offset when i fllip the part in the chuck and do the other side, or you can simply rerefence part Z axis either way will work
Hope this helps  I know its a bit simplistic but some time thats easier.

cheers
Wes
Have a nice Day

Offline DAlgie

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Re: Mach Lathe questions/problems
« Reply #5 on: June 17, 2007, 01:31:05 AM »
Agreed that tool 1 is the reference tool, usually is, and Mach3 lathe is set up to do it like that as well.

Offline Hood

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Re: Mach Lathe questions/problems
« Reply #6 on: February 29, 2008, 03:20:15 PM »
I dont know if it would affect things but have a look and see if you have a max speed set for the spindle pulley, its the only thing I can think of at the moment.
Hood