Messages

311

General Mach Discussion / Re: Setting up my home machine coordinate position, without homing or limit switches

« on: September 02, 2012, 02:49:29 PM »

Ray, would it matter where the motor stopped? If it is stopping on a full step then all the better. Mach zeroes the machine coords when you Home so what the rotational position of the motor is, is irrelevant as far as I can see.
Maybe I am missing something?
Hood

Hood,

Yes, you're missing something.  With no micro-stepping, the driver has a sequence of four output phases it cycles through.  When you hit the hard stop, the motor may stop on phase 1, but the controller may stop on phase 3, since it can't sense where the motor actually stopped.  The first step the driver makes may not move the motor at all, or may even try to move it in the wrong direction.  The result is, you will end up with an error of up to several steps before the motor catches up to where the controller thinks it is.  This is basically the same problem you have with stopping the machine at a specific position, then powering down, and powering up the controller.  The controller will generally power up in one specific phase, and the motor will then be force to that position.  So, after powering back up, the machine is no longer in the same position it was in when powered down, and the error can be up to 2 steps off in either direction.

Regards,
Ray L.

312

General Mach Discussion / Re: Setting up my home machine coordinate position, without homing or limit switches

« on: September 02, 2012, 01:02:30 PM »

MANY stepper machines are set up without homes or limits.  Most set up  hard stops on xyz to bump up against then set ref home. IF you have no switches setup then when you press refhome it sets the machine HOME to the exact spot you are at. simply move to the stops bump up against it and refhome. Once you have refhome then the softlimits can be made active and that will allow you a saftey when running a program just make the Softlimits to be just inside the max travels of the machine.

Bumping the machine up against the stops with a stepper drive causes no harm or foul to the drives or motors.

IF you look at the gen config you will find a check box to make the DRO positions persistant or be the same as when you shut down mach3 when you restart mach3.

Just a thought, (;-)TP

Terry,

That makes no sense to me....  When you run a stepper into a hard stop, the motor will actually stop at one of four full-step positions (assuming a typical 2-phase stepper), but the controller will almost certainly believe the motor to be at a different position that is some unknown number of steps beyond the physical position.  Micro-stepping further clouds things.

Regards,
Ray L.

313

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: August 28, 2012, 04:03:53 PM »

Steve,

Fascinating approach!  Can't wait to see how it works out!

Regards,
Ray L.

314

General Mach Discussion / Re: Mill as Lathe tool offest question

« on: August 26, 2012, 02:36:34 AM »

You should REALLY look at the screenset Calypso Ventures offers for doing turning with a mill (www.calypsoventures.com).  It solves this problem for you very elegantly.  It allows you to run unmodified lathe G-code on a mill WITH support for multiple tools using Y offsets.

Regards,
Ray L.

315

General Mach Discussion / Re: Problems With Mach3 under Windows XP

« on: August 16, 2012, 08:59:35 AM »

"This would mean that the license and Profile would now be in NTFS format. Is an XP system able to read and use the NTFS file format?" - There is no such thing as "NTFS file format".  The file contents are precisely the same, whether you're using DOS, Win 3.x, 95, 98, NT, 2000, XP. Vista or 7.  Only the directory structure and on-disk data organization are different between FAT and NTFS.  The file formats have NEVER changed.

Regards,
Ray L.

316

General Mach Discussion / Re: Possible new project pending feedback on LazyCam software

« on: August 15, 2012, 04:40:14 PM »

Take a look at SheetCAM, MeshCAM, and CamBam.  Which one is best depends on how you work, and what you need to do.  All are inexpensive, well-supported, and light-years better, and more stable, than LazyCAM.

Regards,
Ray L.

317

General Mach Discussion / Re: Problems With Mach3 under Windows XP

« on: August 15, 2012, 03:59:36 PM »

Sounds to me like you need to go into GeneralConfig and set Incremental I,J, then make sure your license file is in the Mach3 root directory.

Regards,
Ray L.

318

General Mach Discussion / Re: Gcode repeat Cycle help

« on: August 14, 2012, 11:12:21 PM »

Rather than cut and paste, put the lines to be repeated into a subroutine, then call the subroutine as many times as needed.

G90G0X0X0X0
G91G1Z-.5F50
M98 P01 L10
M30

O01
X-50F200
Y-2
X50
M99
%

Regards,
Ray L.

319

General Mach Discussion / Re: A Power Drawbar Like No Other....

« on: August 12, 2012, 06:37:00 PM »

Peter,

If my machine didn't already have a spindle brake, I would've just adapted a bicycle disc brake.

Regards,
Ray L.

320

General Mach Discussion / Re: A Power Drawbar Like No Other....

« on: August 10, 2012, 12:56:16 PM »

Peter,

A stepper seems to me like severely over-complicating things.  Perhaps a small AC or DC gear-motor driving a screw.  However, keep in mind, the drawbar needs to generate about 300# of down-force to pop the collet free.  Also, depending on how you couple the drawbar to the PDB, either the drawbar or PDB dhaft needs to turn some to get aligned, before the PDB will come all the way down.  A pneumatic cylinder can easily accommodate the coupling mis-alignment, but a leadscrew would require some kind of heavy spring mechanism to deal with it.  Pneumatic really is the simplest, cheapest solution.

Regards,
Ray L.