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Topics - mhackney

Pages: 1
1
PoKeys / odd Pokey issue...
« on: April 25, 2015, 09:46:27 PM »
I have installed a Pokeys 56U in an aluminum control panel box and configured it do do a few simple things to start:

1) an MPG
2) a 3 position rotary switch for step increment
3) a 4 position rotary switch for axis select (x, y, z, a)
4) two buttons: feed override up and down
5) three buttons: Start, Stop and Hold

I'll add more later but I wanted to start with these. I've verified that all of the functions 2-5 in the list work properly in Mach with the plugin. The MPG also "works" to jog but does not do step mode jogs. I discovered some oddness that when I jog in MPG mode, then go to CONT mode and use the keyboard and then back to MPG mode, the MPG does not work. I have to hit the eStop Mach button and then clear it and then the MPG mode works again. I also noticed, and this is the very odd thing, that the Mach speed override spontaneously decreases - even if I'm not doing anything, the mill is not running and I am just watching the screen. I haven't been able to correlate this to anything I do with the functions above. But, if I disable the Pokey plugin, this does not happen. I then re-enable the plug in and disabled all of the Pokey functions. In this configuration, the speed override also spontaneously decreases. I've tried plugging the Pokeys into a different USB port but the problem still exists.

Not sure what to do about this. My pokey is mounted in the aluminum box panel. There are some other electronics in there - most noticeably the spindle speed controller (KBM-125) and 2 wall warts for 12 and 24V. I am not running the spindle motor when I observe this issue. Everything is grounded to the aluminum box which is then grounded.

Any suggestions on what to do or what might be going on?

Thanks,
Michael

2
My X2 minimill has been running like a champ for a couple of years cutting 1000s of parts for my fly fishing reel kits. A few weeks ago, I decided to to do some upgrades and repack the ball nuts with oversize bearings to remove some backlash. I had enabled backlash comp last year (.002" on X and .003" on Y) to help a bit.

Long story short, after the upgrades and bearing repack I had a problem where the Y axis would slowly skew over the course of a run. I tried several programs that I had used 100s of times and they all failed to varying degrees. I checked all the mechanicals, backlash, make sure backlash comp had been disabled, etc. For several weeks I have been out of commission. I can not hear missed steps when running. I slowed my rapids down from my normal 125IPM to 75IPM and accel from 25 to 5. Still no change. I even ordered and installed a much bigger stepper on Y and the problem persisted.

Today, I went back to basics. I first wrote a little gcode program to exercise the mill. Here it is:

Code: [Select]
M98 P01 L50 (call subroutine 1)
G0X0Y0
G4P4
M98 P02 L50 (call subroutine 2)
G0X0Y0
G4P4
M98 P03 L50 (call subroutine 3)
G0X0Y0
G4P4
M98 P04 L50 (call subroutine 4)
G0X0Y0

M30

O01 (subroutine "01")
(simple short distance movement on Y)
G0Y0
G0Y.1
M99 (return)

O02 (subroutine "02)
(small rectangle on X & Y)
G0Y0
G0X.1
G0Y-.2
G0X0
M99 (return)

O03 (subroutine "03")
(diagonal movement on X & Y)
G0Y.1X.2
G0x0y0
M99 (return)

O04 (subroutine "04")
(small triangle on X &Y)
G0Y.1
G0X.2
G0X0Y0
M99 (return)

%

When I run this, only subroutine 4 introduces the skew along Y. The others do not. In 50 calls, the Y skews about 1/8" (eyeballed). I then switched my X & Y stepper cables to see what I might learn. Now the skew shifts to the X axis and in the same magnitude. If I run 100 cycles, the skew is about 1/4", 150, 3/8" etc - so its cumulative.

Thinking about the amount of skew: my Y "steps per" are roughly 10,000. So, to skew 1/8" would require 1250 (missed) steps, which would be 25 (missed) steps per call to the triangle path! I do not hear anything indicating missed steps. And, the diagonal and back-forth movements on Y do not result in this skew. I re-ran at 7.5 IPM and the same amount of skew occurs.

Then I realized that my previous .003" backlash comp on Y * 50 cycles = .150" - in the ball park of the eyeballed 1/8" skew. I double checked backlash comp and although the checkbox was unchecked to disable it, the X and Y values were present. So I zeroed them and restarted Mach (actually rebooted the PC too). The skew still occurs.

Then I remembered that I have a saved profile from last year before I enabled backlash comp. I loaded it and ran. No skew! It ran flawlessly. I even ran it 10000 cycles and saw no skew! I then restarted Mach and loaded my current profile and again the skew appeared. Restart with the old profile, no skew.

I suppose the easiest thing will be to rebuild a new profile from scratch but this is nagging at me! Anyone have any ideas or configuration parameters that I can check?

cheers,
Michael

3
General Mach Discussion / Odd spindle speed hesitation problem
« on: July 22, 2012, 09:56:07 PM »
I just upgraded my X2 minimill to enable spindle speed and flood coolant control. I'm using a Gecko G540. I immediately started experiencing a strange issue when running a program. The spindle periodically decreases speed momentarily. It doesnt completely stop, just slows for a split second. When I run the spindle from the original speed control pot it Is steady.

Then I tried control from the mdi. I entered an M3 S5000 on the mdi and the spindle spins up and is rock stable - just like when I use the pot manually. Then, I clicked the coolant on button and the spindle momentarily hesitated. Turning the flood on and off sporadically does this but not every time. Then I excersised movement with G0 command and that worked fine. Then I loaded a program and cut air with the coolant off. For most movements, the spindle was fine but for some arc moves (I cut a lot of disks and rings) I occasionallY get hesitations when the line of code executes.

If I run the spindle from the pot and turn the flood on and off there is no change. So it appears not to be an electronic issue I think but maybe a Mach issue. My kernel speed is at the lowest although the machine most likely culd support greater. I was going to try that but Mach warns that all axis will have to be recalibrated if I change the kernel speed. I have a lot of parts to cut in the next week so I can't mess with that right now.

What do you think about the above behavior? I wouldn't think that turning the flood on would take that much processing pow to cause a momentary stall on the spindle. As I write this I realize that flood has a 3 second pause to allow time for it to flow. I will turn that off (to 0) and see if that has any effect.

Cheers and thanks for the help.

Michael

4
General Mach Discussion / How do I clear a fixture?
« on: November 10, 2011, 11:12:17 AM »
Firstly, I use CamBam for my cam app. I am milling the perimeter of some aluminum disks and have a fixture that clamps the disk through its center hole. Imagine a 2" diameter washer on top of a 3" diameter part held with a 1/4" socket cap screw. I would like to zero my at the part's top surface and X=Y=0 at the center of the disk. But, there is a cap screw and the large washer there! If I move my Z up to .25" above the surface of the disk (which gives me the clearance I need), it takes forever as the mill cuts air through that 1/4" to get to the part (which is .062" thick). There has to be a way to program this but I don't even know what this is called to be able to google it!

Help greatly appreciated.

Cheers,
Michael

5
General Mach Discussion / New odd Y (lack of) movement problem
« on: January 01, 2010, 12:40:52 PM »
So now that I understand machine coordinates and have Mach3 and my mini mill configured I've been using CamBam to draw some simple shapes and text and draw them in Mach3 with a pencil mounted. Today, I was prepping to actually cut some metal :) At first, my "dry runs" were good, everything was working fine. I am trying to make a simple rectangular cut out for my G540 in a thin steel front panel on my electronics box. I was going to do one more run and as it ran, the Y axis did not move at all. I spent a lot of time trying to debug with no effect. The Y and Z worked fine. I then went to the tab where I could manually enter G code. A G0 Y1 works fine, a G1 Y1 shows the table moving on the Mach display but the stepper is not turning and the physical table does not move. I reset machine origins, work origin, and tested everything I could. G1 Y just will not work now and it was earlier today.

Any help or debugging suggestions greatly appreciated!

Cheers,
Michael

6
General Mach Discussion / Y-axis confusion
« on: December 29, 2009, 03:55:13 PM »
Ok, I completed installing a CNCFusion kit on my MicroMark (X2) mill. That all went smoothly, electronics working, etc. Then I started configuring Mach3. Worked through the videos (which were great!) and the docs. I do not have home or limit switches on my mill at this time. But, I put machine zero with the X table all the way right, Y table all the way forward, and Z at top.

   soft Max    Soft Min
X 8.50"        0"
Y 3.90"        0"
Z  -8.40"      0'

This all makes sense to me. When I jog, everything moves in the correct directions and I understand the movement. Now for the problem:

I created a little G code to draw a rectangle with a pencil chucked in the mill.

G00 X2
G00 Y1
G00 X0
G00 Y0

I then set the wok coordinates to the middle of my table and set X=Y=Z=0 (pencil touching the paper). When I run the code the table moves towards the + direction (the same direction that the -> arrow key makes it move) for 2". Then, the Y moves. It moves in the direction the ^ up arrow key moves it. But, on the Tool Table display on the Program Run screen, the Y moves up on the display - which is the opposite of what the Y is actually doing. So, I end up with a figure that is flipped in the Y direction.

I've messed with reversing the Y, etc but can't figure this out.

thanks in advance,
Michael

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