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Messages - alenz

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General Mach Discussion / Re: Backlash comp help
« on: September 01, 2010, 12:13:18 AM »
Dave, there is an easy way to measure backlash directly that you might like to try. Using the same setup that you described, move into the indicator 0.25 in or so, (approx. mid-stroke). Now set BOTH the DRO and the indicator to ZERO. Continue in the SAME direction for another 0.1 or 0.15 in, (just a bit more than the expected backlash). Now reverse direction and step back to the DRO zero.  Now read the backlash directly from the indicator. As a check continue movement for a little more than the backlash and then step back to the DRO zero. The indicator will (should) read zero. This should repeat precisely all day long, (for that location of the lead screw). If not then as others have suggested, there is definitely some other problem in addition to backlash.
Note that the backlash probably will not be consistent throughout the length of the lead screw.  It is usually greater in the center (due to the most wear) than at the ends. You will want to take that into account when you do set your backlash comp.

Another thing that is troublesome is that you commanded a .007 move but only got .0066 movement. That is unrelated to backlash since there was no reverse movement involved. It would imply that it is a calib (steps/in) error, but that is too short an interval to draw that conclusion. But the bottom line is that the DRO and indicator should agree. Possibly another clue to a mechanical problem? Have you checked your calib over a longer distance?


General Mach Discussion / Re: Rotational speed
« on: August 21, 2010, 03:46:41 AM »
Great :)

General Mach Discussion / Re: Rotational speed
« on: August 21, 2010, 02:35:52 AM »
What do you have your A-Axis velocity set to in Config > Motor Tuning? It sounds like it’s set too low. For your example, (100 in/min & 2.0 in radius) it should be 2860 deg/min or higher. Note that the entry is in deg/min (even tho the header reads ‘In’s or mm’s per min’.) If it is set low you will get the results you describe.

General Mach Discussion / Re: WHERE'S THE DAY COUNTER ???
« on: August 17, 2010, 01:18:50 AM »
Just post it here and let somebody else do the hard work, Bob. :) You shouldn't have to micromanage things like that. Better still, train your wife like Chris Botha did to run the cnc. And the Cad. And the Cam. And the laundry. And the cooking. And the dishes. And the yard work. And vehicle maintenance. And beer retrieval. And the list goes on. A role model for all of us, indeed!!!
This wants looking into. Do you have a link?

General Mach Discussion / Re: High speed spindle recommendations
« on: August 13, 2010, 03:25:43 PM »
Bob, the air conditioning is a requirement for my comfort, nothing to do with the equipment. :)

General Mach Discussion / Re: High speed spindle recommendations
« on: August 12, 2010, 10:31:37 PM »

Another option might be an air spindle. There are pros and cons. I designed and fabed a Sherline air spindle adapter (which I was rather proud of <grin>) and posted it to one of the hobby sites.


 For my purpose it turned out to be less than acceptable. My hobby mill is inside the house (need to be inside the AC here in southern Louisiana) and the air spindle noise would wake the dead, or in my case a sleeping wife. Also the air requirement exceeds the capacity of the small ‘quiet’ hobby compressors and dragging an air hose from the garage into the house wasn’t convenient.  In the end, even tho it worked very well, I gave up on it.

In a shop environment where you have plenty of air and noise isn’t such an issue, an air spindle might be worth considering.

Al Lenz

General Mach Discussion / Re: Z Axis Drifting or Loosing Steps?
« on: July 09, 2010, 02:39:42 AM »
I seem to remember a similar situation some time ago where the fix was to reverse the step low/high in config/ports and  pins. (Then toggle the reverse setting in config/homing/limits to keep movement in the proper direction). It's a long shot, but will only take a minute to check out.

General Mach Discussion / Re: What does "Allow Wave Files" do?
« on: July 04, 2010, 05:30:38 AM »
Ger21, thanks for the response. I was hoping to use something more descriptive than integers, but I see (RTFM) that it isn’t allowed  :).

BR529, I never would have thought of using a sub, but that does indeed do what I asked for.  Thank you. In fact I will probably use it for some macros that I’m sure I won’t remember six months from now, (CRS comes with age >:(). I agree tho (as I think you implied), it’s not a practicable substitute for a simple catalog.

BUT in the course of testing I ran into an apparent anomaly.

I found that a sub called from a separate file doesn’t respond (for me) the same as one called from within the same file. If the sub is in a separate file then the flow returns TWO lines after the M98 calling line. That is, it skips over the line following the M98. The fix is to stuff a comment or other filler after the M98 but that shouldn’t be required.

This is my test code:

G00 X0 Y0 Z0 F20
M98 (SpeakHello.txt)
G01 X.25 Y0 (Skips this line)
G01 X.25 Y.25
M98 P10
G01 X0 Y.25 (Reads this line)
G01 X0 Y0



(Macro M777)
Speak "Hello"

Any ideas? What am I overlooking? Can anyone else duplicate it?

Thanks, Al Lenz

P.S. I’m using .042.027

General Mach Discussion / Re: What does "Allow Wave Files" do?
« on: July 03, 2010, 02:03:57 AM »
That’s neat, I never knew mach could talk! Wonder what else it can do that I’m unaware of.  For instance is there a way to name macros and call them from Gcode?  (I’ve tried and it didn’t work for me.) This time next week I will have forgot what I called this one. How do you folks keep track of macros other than a separate data base?

General Mach Discussion / Re: Mach 3 and 4th Axis
« on: July 02, 2010, 07:09:28 PM »
Jim, are you sure you have your work oriented properly? The A-axis of the cylinder is parallel with the machine X-axis. So if you look at the X Y Z drawing, it will wrap along the Y-axis. If you want your text to wrap lengthwise around the cylinder then it must be drawn with the text height as X and the text length as Y. (Rotated 90 deg from normal)

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