Messages

21

General Mach Discussion / Re: G4 versus Sleep

« on: October 06, 2009, 09:15:35 AM »

YES

22

General Mach Discussion / Re: G4 versus Sleep

« on: October 05, 2009, 11:46:55 PM »

Yes it is milliseconds. Note that the sleep 100 command worked. The dwell command did not work regardless of how long I made the dwell time. If I inserted a break in the code and stopped between the mode changes and the move, everything worked fine as well.

If the dwell code did not work for this example, I doubt it is really doing anything when inserted between a DRO change and an axis move. The macros that I have seen that use the dwell coomand have a comment that says "pause for the DRO to update." I am wondering if the dwell is even needed or if I shoul be using sleep instead of dwell for those instances as well.

23

General Mach Discussion / G4 versus Sleep

« on: October 05, 2009, 11:34:16 PM »

Here is a script of code that raises the question of when to use G4 versus sleep.
This code works:
   
   Code "G90"                 ' Set absolute mode
   DoOEMButton (180)     ' Set work coordinate mode on
   Sleep 100   
   New_Z = GetDRO(2) + 0.2
   Code "G0 Z" & New_Z

This code does not work regardless of the specified dwell time:

   Code "G90"
   DoOEMButton (180)
   Code "G4 P0.1"   
   New_Z = GetDRO(2) + 0.2
   Code "G0 Z" & New_Z

I have seen the dwell command (Code "G4 P0.1") used many times to delay movement of an axis  immediately after a DRO is changed by code. Should the dwell command (G4) be used or should an equivalent sleep command be used? I am running a SmoothStepper which may be complicating this.

24

General Mach Discussion / Pause for DRO Update

« on: October 03, 2009, 01:14:35 AM »

In many macros I see that there is a 1/4 second pause added after a DRO is updated by the code.  Is this necessary? Also, if the code has the axis moving, such as during a G31 probe move, is a pause needed before reading the DRO or does the DRO closely track the progress of the move. I guess I am asking if pauses are necessray and if so when are they needed...after the code updates a DRO, before a DRO is read after a move, or both?

Thanks,
Kent

25

General Mach Discussion / Re: Auto Router On With Cycle Start

« on: September 10, 2009, 09:27:04 AM »

Sounds like a good plan

If you want to dry-run a program you'll need a lockout of some kind to disable the feed hold though. Shouldn't be hard to do.

I am implementing the control in a Brain. I can disable the brain to dry-run or I may add a button to the Mach screen that the Brain will read for disabling.

26

General Mach Discussion / Re: Auto Router On With Cycle Start

« on: September 09, 2009, 03:00:37 PM »

I have changed my plan.

My current plan is to only turn the router on using an M3/M4 command. I will then have a circuit issue a feed hold if router current is not detected with 1/2 second of the spindle on LED being true. That will catch the condition when you start the run and have left the router switch in the off position.

Thanks for the feedback.
Kent

27

General Mach Discussion / Re: Auto Router On With Cycle Start

« on: September 01, 2009, 11:49:24 PM »

BAD IDEA, (;-) TP

Can you explain your thoughts on why it is a bad idea?  Do you use M3 now or do you manually switch the spindle on?

28

General Mach Discussion / Re: Auto Router On With Cycle Start

« on: September 01, 2009, 05:53:32 PM »

My purpose for the relay is so that I can have Mach turn the router on when it starts a job. I had planned to put an M3 command at the beginning of the G-Code file to do that. However, rather than edit this command into the file, I thought why not have a Brain turn the router on for me anytime I perform a cycle start. The router has an on/off switch, so I will turn that off anytime I am changing bits.

If a person plans to start cutting anytime they click cycle start, then I think the Brain approach makes sense. However, in practical use, I did not know if people hit cycle start for other reasons. The only one I could think of is if you plan to cut air without a bit and without the router turned on. I imagine that is rarely done.

29

General Mach Discussion / Auto Router On With Cycle Start

« on: September 01, 2009, 05:05:56 PM »

I am very new to CNC and am looking for feedback from the veterans. I am building a CNC router. I have the router connected to a solid state relay that is controlled by Output #1. I had planned to edit the g-code file to add the router on comand at the beginning of the file. However, why not use a Brain to turn the router on anytime cycle start is clicked? This should be no more "dangerous" than having the router power on when the command is embedded in the g-code. If I want to cut air as a test, I would disable the brain. Is there any reason not to take this approach?

30

SmoothStepper USB / Overrun Limits Using SS

« on: August 31, 2009, 11:42:09 AM »

I am using hall effect sensors for my limit switches. I use a small button magnet and thus the limit switch is only activated over a short range. If the axis is moving fast you will get a short duration pulse out of the limit switch. It appears that the duration is not long enough for the SmoothStepper to register the limit and thus I can run right past the limit switch. I am not sure at what speed it will work, but I know I have overrun it at 300 ipm.  Slow speed operation, such as when I am homing, works fine. Has anyone else experienced this?