Messages

11

General Mach Discussion / Y-axis losing position

« on: June 14, 2013, 03:06:24 AM »

First, I apologize for hijacking this thread... but it is so close to what I'm going through, it didn't seem worth starting a fresh thread.

Also a Chinese machine converted from factory pendant/controller to Mach3, but using PMDX boards... Also at about 90% (spindle speed is not linear).

Trying to cut two sided 3D item out of wood blocks, using code generated by MeshCam Art V5. Code proofs fine in CutViewer.

Problem has been Y-axis losing position, so when other side is machined, it is out of register. Now the Z-axis is losing position, and has both gone above and below reference zero.

Have systematically eliminated heay load electric equipment in the shop. upgraded line filtering power strip for the computer. cleaned and lubed slideways.

Stepper motor tuning steps calculated using a 1" dial indicator. Velocity originally set to manufacture's listed "working speed", but slowed down to 90% as part of troubleshooting. Acceleration... adjusted for 45 degree ramps (I read somewhere years ago). Z-axis motor specs are way different than XY.

Anyway, have been making a lot of chips without a useable sample so far. Any nudge toward identifying the source would be greatly appreciated.

http://www.alibaba.com/product-gs/628157563/cnc_tombstone_engraving_machine.html

12

General Mach Discussion / Re: Rectangular Pockets have curved ends

« on: June 14, 2013, 02:09:08 AM »

And here's the xml...

13

General Mach Discussion / Rectangular Pockets have curved ends

« on: June 14, 2013, 02:05:34 AM »

While trying to troubleshoot a gaining/losing step problem, I developed a test block code, hoping to help identify the problem... to be subject of another thread.

The current issue is the actual run produces odd curved ends on what should be rectangular ended slots. I thought it was a result of Constant Velocity, so changed to Exact Stops, and the problem got worse.

The cutter is a 4FL 1/4" carbide ball mill held in an ER11 on-size fractional collet, running at 19000 rpm, 175 ipm, 0.3125" depth per pass,in soft fir... so deflection shouldn't be a factor.

The attached pics show the run result, TurboCAD/CAM path and simulation, and CutViewer simulation. I also checked the code, and it defines rectangular paths.

Dial indicator check shows no backlash. Mach3 ver .066.

Any suggestions?

14

General Mach Discussion / Re: Unexpected Crop Circles

« on: May 20, 2013, 06:40:54 PM »

I'll go with his last words...

"So if it works, keep it."  
(Incremental IJ)

15

General Mach Discussion / Re: Unexpected Crop Circles

« on: May 20, 2013, 01:52:50 PM »

Gerry,

I got a definite maybe response from Robert:

"I just had to go back in my code to double check but Meshcam should be
outputting absolute IJ. I may have to do some more testing to make sure
I'm not reading old code wrong but that's what it looks like to me.

For what it's worth, I use Mach3 on a Tormach and it works as-is.

That being said, your machine may have a different default configuration
so if it works, keep it."
-Robert

16

General Mach Discussion / Re: Unexpected Crop Circles

« on: May 20, 2013, 02:32:13 AM »

And... Presto! There it is! 

Once again, assuming brought unwanted results. I assumed the pre-scan of the code would trigger the change.

Oh well... cycled dry with machine off. No harm, no foul, nothing to break... all good.

I'm not a Beta user of MeshCAM, but Robert called me personally to thank me for my license purchase. Sadly, the five years I spent away from my shop while machining for a paycheck, along with four strokes, put a dent in the 64+ year old gray cells. 

Thanks, Paul

17

General Mach Discussion / Re: Unexpected Crop Circles

« on: May 19, 2013, 09:41:00 PM »

IJ mode is modal. If your g-code has a G91.1 in it, it is changing it in General Config, and it should remain Incremental until you change it, or run code with a G90.1 in it, which will change it back to Absolute IJ.

It's good practice to have your CAM software add the G90.1 or G91.1 to your g-code, which will automatically set Mach3 to the correct IJ mode for that particular code. In almost all cases, this would be G91.1.
[/quote]

I looked at General Config after loading my code with added G91.1, and the Absolute IJ button is still selected?

I modified my MeshCAM Mach3 Post Processor to include the G91.1. And I emailed a note to the MeshCAM author asking for his input on the issue. I'm guessing a large percentage of his customers are running Mach3 systems.

Paul

18

General Mach Discussion / Re: Unexpected Crop Circles

« on: May 19, 2013, 07:48:36 PM »

Well... I started this topic saying I had Mental cobwebs to clear out! 

Thanks to all for the assistance.

Paul

19

General Mach Discussion / Re: Unexpected Crop Circles

« on: May 19, 2013, 04:41:27 PM »

No... The pic was sent to me by the client after running the attached code. The previous attached code was the one I ran at his site and witnessed the behavior.

20

General Mach Discussion / Re: Unexpected Crop Circles

« on: May 19, 2013, 03:13:50 PM »

I have to admit... I'm confused by the use of absolute distance combined with incremental IJ?

On line 5788 the XY coordinates are absolute, which goes along with the G90 placed in the header by MeshCAM.

In addition to changing the G90.1 to G91.1, should General Config also be changed to Incremental IJ?

I could use some clarification instruction. Just do it because it works is not a real confidence builder.