need help configuring LinuxCNC

I built my own CNC machine from the book at buildyourcnc.com/book.aspx and up until now, I have been trying to use Mach3. The z-axis keeps dropping, and since I have checked EVERYthing else, am thought I'd give LinuxCNC a try - I prefer Ubuntu Linux anyway.

I managed to figure the configuration out enough so that I could get the machine to move, but the distance it moves is WAY wrong. Can someone please help me figure this out.

I am using a TB6560 3-axis controller with KL23H286-20-8B 425 oz stepper motors. The leadscrew is a 1/2" 10TPI threaded rod from any hardware store. I am attaching the datasheet for the stepper motor and the manual for the controller as well as the .ini file created by the StepConfWizard.

Here are the parameters as entered into Mach3:

Port Setup
Port #1: Address 0x378
Kernel Speed: 35000Hz

Motor Tuning
X-, Y- and Z-Axis

• Steps Per - 41600
• Velocity - 10
• Acceleration - 7
• Step Pulse - 5
• Dir Pulse - 5

Motor Output
X-axis: Step Pin #1, Dir Pin # 7, Dir Active Low
Y-axis: Step Pin #8, Dir Pin # 3, Dir Active Low
Z-axis: Step Pin #5, Dir Pin # 4, Dir Active High

Output Signals
Enable 1: Pin #14, Active High
Enable 2: Pin #2, Active High
Enable 3: Pin #6, Active High
Output 1: Pin #9, Active High

Input Signals
X++: Pin #10, Active High
X--: Pin #10, Active High
X home: Pin #10, Active High
Y++: Pin #11, Active High
Y--: Pin #11, Active High
Y home: Pin #11, Active High
Z++: Pin #12, Active Low
Y--: Pin #12, Active Low
Z home: Pin #12, Active Low
E Stop: Pin #13, Active Low

I hope this is enough information to go on. I will appreciate ANY help at all! Thanks...

EDIT: I cannot get the PDF for the controller to upload so I uploaded it to my server:
www.robotsandcomputers.com/CNC-build/TB6560_3Axis_Driver.pdf

Hi

.........................but the distance it moves is WAY wrong

You will have to be specific, it will be related to the SCALE= figure in your .ini file

Your micro-stepping, gearing, thread pitch all comes into this calculation, which is the number of step pulses per machine unit, in your case presumably 1 inch

linuxcnc.org/docs/2.5/html/config/ini_co...d_sub_axis_section_a

So for instance, if you move 1.5" when commanding 1", your scale figure is 66% of what it should be (move 150%), etc etc.

regards

I'm sorry. I told it to move the Z-axis 2", but it only moved it like .178" using the default driver timing settings - I couldn't figure out HOW to determine them based on the documentation that I had. I did try different presets and, using one of them (I forget which right off hand), I did get the axis to move .48" when told to move 2"... Not sure if that helps...

You need to look at the docs and find out what the stepping presets are

A stepper takes 200 pulses of 1.8deg movs for one revolution, if you are half stepping for instance that becomes 400

Then your 10 tpi thread will take 10 revs to move 1", so that is SCALE=4000 (assuming there is not some other gearing)

Your scale is 41,000, so I suggest therein lies your problem

The formula is in the link I gave

regards

PS

If you divide 2 by .178 and then divide 41,000 by that figure you get near 4000 but a bit out from it

If you divide 2 by .48 and then divide 41,000 by that figure you get near 1000 but a bit out from it

You may find that your 10tpi screw is far from accurately pitched and you will have to fiddle with the theoretical figures to achieve the required travel, but this may not be accurate throughout its length
The ultimate answer is probably a ballscrew.

Well, I have the controller set to 1/8 microstepping (I don't know why... ) but I did tell StepConf that Drive Microstepping was 8.0. Is that not correct?

It does come back to zero consistently - which is more than I can say for Mach3!