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I need help with Mach3

Posted: Sat Mar 01, 2014 12:02 am
by will1384
I had used Mach3 in the past with the first CNC router I had, but I was given all the numbers to enter into the mach3 motor tuning screen, but with the Shapeoko 2 I have been trying to do the math on my own.

I have a blue chinese CNC controller box that was made for a 6040 CNC mill, I got it used on eBay and fixed it up a bit, it uses TB6560 chips, installed on four separate driver cards.

What I want to do, is use the blue chinese CNC controller box with Mach3 to:

(1) CNC routing using only 3 drivers
(2) 3D printing, using the 4th driver to drive the extruder

But I can't even get Mach3 to cut anything correctively, it seams to move to far in the different axes, and then cut to small, I have Mach3 setup in inches, but I have tried in millimeters, I am using Cut2D to generate G-code in inches, the Shapeoko 2 does move in the direction of the keyboard arrow keys, and the TB6560 driver cards are set to 1/8 microstep.

Here is the math I have done, I am not good at math :?

----The Stepper Motor:
Steps Per Revolution 200

----Aluminum GT2 Pulley:
Teeth 20
Pitch 2mm

----GT2 Belting:
Width 6mm
Pitch 2mm

----Usefull Info:
1 Inch = 25.4mm

----M8x1.25 Threaded Rod:
1.25mm of travel for one rotation
20.32 Threads per inch

25.4mm / 1.25mm = 20.32 turns per inch

----X and Y Axis Math in Millimeters:

20 Teeth x 2mm Pitch = 40mm

200 Steps Per Revolution * 8 Microstepping = 1600

1600 / 40 = 40

40 Steps per mm

----X and Y Axis Math in Inches:

2mm = 0.0787402 inch

20 Teeth x 0.0787402 inch = 1.574804

200 Steps Per Revolution * 8 Microstepping = 1600

1600 / 1.574804 = 1015.99945136

1015.999 Steps per Inch

----Z-Axis Math in Millimeters:

200 Steps Per Revolution * 8 Microstepping / 1.25mm Length of travel for one rotation

200 * 8 / 1.25 = 1280

1280 Steps per mm

----Z-Axis Math in Inches:

200 Steps Per Revolution * 8 Microstepping = 1600

1600 * 20.32 turns per inch = 32512

Re: I need help with Mach3

Posted: Sat Mar 01, 2014 3:34 am
by will1384
I tried LinuxCNC and now I wonder if my microstepping is set to 1/8

here is a screen shot

Image

X and Y axis were set the same, I clamped a ruler to the makerslide and told LinuxCNC to move 1 inch, and adjusted the Leadscrew Pitch numbers until the CNC router moved about 1 inch from what I could see.

Re: I need help with Mach3

Posted: Sat Mar 01, 2014 4:26 am
by Brian
with 1/8 microstepping my shapeoko 2 is 1016 steps per in calculated. I have yet to take a dial gauge to it to confirm but its working nicely. Ill have to check mach when i get back to my shop for the z axis. What is your vel/accel? Those TB6560 are temperamental drivers from what I've found, don't like to be pushed very hard.

Re: I need help with Mach3

Posted: Sun Mar 02, 2014 2:23 am
by will1384
I used LinuxCNC to test what Microstepping the drivers were set to, because there is no documentation :roll: , I made sure Microstepping was set to 8, and for "Leadscrew Pitch" I think I set it to 0.635, to get 1016 Steps / in, then used the "Test this Axis" to move the Axis one half inch and used a ruler to see if it was moving the correct amount, most of the time when I tested a dip switch setting it moved enough to hit the end stops, so I had to be careful, the drivers were not set to 8 Microstepping if this test works, also I found my Z-Axis driver dip switch was slightly melted and not working, I had used a hot-air rework station to fix the drivers and I guess I got to close to the dip switch, I was able to fix the dip switch.

I then tried Mach3 again, and it still acts strange, I think I am going to start from scratch on Mach3 and delete all the settings.

Re: I need help with Mach3

Posted: Sun Mar 02, 2014 7:44 pm
by Brian
id recommend stepping up to a dial gauge as opposed to a ruler, much more accurate. Mach 3 has a step per in calculator for use with a dial gauge.

Re: I need help with Mach3

Posted: Mon Mar 03, 2014 8:56 pm
by will1384
Brian wrote:id recommend stepping up to a dial gauge as opposed to a ruler, much more accurate. Mach 3 has a step per in calculator for use with a dial gauge.
I have one on order now.

I found this page

RepRap Calculator3
http://calculator.josefprusa.cz/#steppers

And

Steps Per Unit Calculator spread sheet - I tried it with LibreOffice
http://www.machsupport.com/forum/index. ... ic=16315.0

Here are some screen captures from running the Steps Per Unit Calculator spread sheet.

X and Y axis
Image

Z-Axis
Image

I am going to delete the Mach3 configuration and start from scratch using the figures above.

Re: I need help with Mach3

Posted: Tue Mar 04, 2014 9:43 pm
by will1384
Yep, deleting the Mach3 configuration helped, I am able to make it move 1 inch / 25.4mm in Mach3's "Axis Calibration".