[Khalid]

Recently i have retrofitted Radial drill machine and currently having an issue with 'drifting' + in the X axis. I have a work piece on which i have drill some holes and then profile milling upto 4mm deep with 0.5mm DOC per pass... After centre drilling and final drilling of 7mm dia drill 4mm deep, i started milling with 3-flutes 6mm end mill... After 1 Hour the job was finished and the end mill went to its zero position about 2mm toward the positive X-axis...

I saw the profile and i found step ladder (each pass with little drift toward X) toward one side whereas i have removed material from the other end...In several levels in Z I can see by the faces of the pocket that it drifts (steps on one side, smooth on the other).. This figure will depend upon the length of program run, longer program, bigger drift. Any ideas?

I have backlash compensation On.
The computer is dedicated to Mach software only.

Material SS-316 solid bar
Depth per pass= 0.5mm
Feed: 2IPM
Dormer end Mill HSco 3-flutes
Spindle Speed= 800 RPM
Ramping


Kind regards
Khalid

[Khalid]

Any thoughts?

[CarveOne]

Any thoughts?

Hi Khalid,

I had a very similar problem when I tried cutting aluminum on my second machine. The gcode did the same thing, to a lesser degree when I tried it on my 25x37 machine. Both machines do not have the problem if I run the gcode using EMC2/Ubuntu Linux. I have not spent any time trying to determine why Mach3/Vista has this problem, but I can say that the Vista computer also has EMC2/Ubuntu as a dual boot setup and the problem is related to Mach3 and/or Vista, not the Acer computer's hardware.

CarveOne

[Khalid]

Hi CarveOne,
I am running Mach3 on Win XP... I get electric shock when touching the controller panel.. Is this a cause?

[Realmseeker]

Howdy,

I had a similar problem too. Check to see if the bottom of your cut (from the inside edge of the last step to the other side) is the correct distance. I did a bunch of pocket cuts till I got the problem corrected.

The solution I had given to me, was to input larger step and direction pulses in Mach under motor tuning. I had to get mine up to 17-19 in each to get rid of it. What the max setting you can put in each and what not I don't know. Also I don't know what determines what is the max. It seems to vary sometimes and mach sets it lower after I input a different number.

I can not say whether this is noise or not enough power coming from your printer port (I'd like to know the reason as well), but this seems to fix the problem.

Hope this helps, GL!


Jordan

[Al_The_Man]

Hi CarveOne,
I am running Mach3 on Win XP... I get electric shock when touching the controller panel.. Is this a cause?

I am not sure what the supply method is in Pakistan, but it would seem you do not have the machine properly grounded, You should not receive a shock, what ever system is used.
Not safe the way it is.
Also ground issues can cause havoc with PC based systems especially.
Al.

[Khalid]

I am not sure what the supply method is in Pakistan, but it would seem you do not have the machine properly grounded, You should not receive a shock, what ever system is used.
Not safe the way it is.
Also ground issues can cause havoc with PC based systems especially.
Al.

Al, I will redo all wirings and make the machine and control panel ground tomorrow... Safety First ...

One possibility can happen in this step ladder cause.. If i have wrongly entered the backlash compensation for X-axis in Mach3.. Could it cause the step ladder formation for each pass? Lets suppose the actual backlash is 0.2 mm and i entered it 0.1mm.. will i get a step ladder effect then?

[Khalid]

Howdy,

I had a similar problem too. Check to see if the bottom of your cut (from the inside edge of the last step to the other side) is the correct distance. I did a bunch of pocket cuts till I got the problem corrected.

The solution I had given to me, was to input larger step and direction pulses in Mach under motor tuning. I had to get mine up to 17-19 in each to get rid of it. What the max setting you can put in each and what not I don't know. Also I don't know what determines what is the max. It seems to vary sometimes and mach sets it lower after I input a different number.

I can not say whether this is noise or not enough power coming from your printer port (I'd like to know the reason as well), but this seems to fix the problem.

Hope this helps, GL!


Jordan

Okay... This is good point.. When i put 5 in step and direction pulse, Mach make it 3 and sometime to 1... I don't know why... I will try 1/2 step sherline mode tomorrow... will show you the results...

[CarveOne]

Hi CarveOne,
I am running Mach3 on Win XP... I get electric shock when touching the controller panel.. Is this a cause?

Al_The_Man has already answered this question and I will agree with him. Getting shocked or even a little tingle is a sign of wiring problems that need to be corrected as soon as possible. Electronic equipment will not work reliably with improper grounding.

Mach3 runs best with Win XP or XP Pro. Unfortunately, I gave away my only Win XP Pro computer and bought a new computer with Vista Business Edition. The new computer running Vista and Mach3 is having the step over problem, unless I reboot the new computer and load Ubuntu/EMC2 instead.

CarveOne

[louieatienza]

Check if your z axis is perfectly perpendicular to the surface, and that it doesn't drift as it moves up and down...

[Khalid]

Check if your z axis is perfectly perpendicular to the surface, and that it doesn't drift as it moves up and down...

Thats a really nice point... You mean for each pass depth Z-axis may add some drift... But why in only one direction?...
I am using Quill as Z-axis and i have 0.2mm clearance between the spindle quil and the Bush...

[Khalid]

Today I checked all of the wiring.. The problematic X-axis wiring , i have found short circuit situation.. The 6 wires coming out of Logic MOSFETS... The connect at the Motor power wire was darken due to continuous arcing... I think this may be the problem..

One of the motor coil was getting uneven voltages due to this arcing short circuit.. I don't know the right term... Is this may be Problem?\
Any Thoughts? How can this cause drifting of axis one side?

PS:

I also increased the Pulse width and ran it with 1/2 pulse sherline mode, but the problem was not solved...


Before opening the controller i checked whether the problem in the axis?.. For this i calibrated the X-axis , but every time i got drift toward positive X-axis.. As this was done during the calibration, so no cutting forces and no Quill clearance plays any role here...So the drifting was totally not related to mechanical... Then i swap the Y-axis motor with X-axis, and i always got the results within 0.03mm range for the same axis.. This means i have no mechanical problem..

[louieatienza]

Thats a really nice point... You mean for each pass depth Z-axis may add some drift... But why in only one direction?...
I am using Quill as Z-axis and i have 0.2mm clearance between the spindle quil and the Bush...

What happens is if the Z is not totally perpendicular, as it steps down in depth, the corner of the bit will "dig in" slightly on one side, and on the other side, it's tilted away, so there'll be no "step" on that side. If you marked the center of where the "steps" occur and the center of where they are smooth, and draw a line over those two points, then check for perpendicular along that line. It is my guess that relative to that line, your Z may be out of alignment....

To test if this is the case, cut a thick piece of material like plastic or pvc board about an inch thick, then check the squareness of the smooth edge against a machinist's square... or, cut a pocket, using raster method, stepping the width of the bit, in the angle described by the line above, and see if you leave ridges on the bottom of the pocket...

[Khalid]

Today i have spent a lot to organize the wiring... I make all the power wiring far away from the controller cards...So that interference zone should be far far away from the Step/Dir pulses....
Tomorrow i will retest the system.. I think this will eliminate the electrical issues too...

The attached picture shows the MOSFET wiring location to the connector...and the smoldered joint...