[youngmasterpete]

Hello my name is pete. I am building my first ever cnc machine, I have never built or programmed one before so please treat me like a complete noob, as im new to all of this.

I have built a Rack and pinion drive machine and will be using mach3 cnc to control it. I am having trouble setting the printing area size and motor units.

For practice I have been trying to cut the 'roadrunner' example, although it appears to either too large or ridiculously small.
Does anyone know what size the actual road runner is meant to be?

I am using nema 23 stepper motors:

Zapp Automation Ltd - Stepper motors & Stepper Motor Drivers - Servo motors and Servo Motor Drivers - Ballscrews & linear motion products. : SY57STH51-3008B Nema 23 Stepper motor [SY57STH51-3008B] - £22.80

and the system 4 controller board, from diycnc.com
System4

and the SSB10/12B pinion spur from zappautomation:
Zapp Automation Ltd - Stepper motors & Stepper Motor Drivers - Servo motors and Servo Motor Drivers - Ballscrews & linear motion products. : SPUR GEAR 10-60 Tooth X 1.0 MODULE [SS10/#] - £0.00

I currently have my steps per unit set to 43 (decided through trial and error). This seems to have made it so that, 1.0000 units on screen = 1.0000mm on my machine. Im sure this isn't the right way to do this. Can somebody please talk me through setting up my motor steps correctly.

Thank you
Pete.

[gtotten89]

the way i did it was in the settings tab or ALT-6 and there is an axis calibration button right there above the reset button. Go through that and tell it to move a few units whether its inches or mm it doesnt matter just make sure you tell mach what unit you want to be using. See how far the machine actually moved and type it in and it should give you an updated steps per unit and will ask if you want to update. Do this tell you got each axis moving properly and you should be ready to go. Hope this helps.

[youngmasterpete]

the way i did it was in the settings tab or ALT-6 and there is an axis calibration button right there above the reset button. Go through that and tell it to move a few units whether its inches or mm it doesnt matter just make sure you tell mach what unit you want to be using. See how far the machine actually moved and type it in and it should give you an updated steps per unit and will ask if you want to update. Do this tell you got each axis moving properly and you should be ready to go. Hope this helps.

Thank you for the suggestion, I have gone through this process and receive values of 4.1 steps per unit, which is similar to the my trial and error values. But doesn't that seem such a small number. I have seen seen other people saying their steps are in the 1000's per unit.
It also means when the motors are set to these values the roadrunner image is so small (only a few mm across).
Surely that cannot be correct

[gtotten89]

It depends on the gcode for the road runner. If the gcode is for inches and you are doing it in mm than yes it is going to be to small. You might have to do some editing or switch the steps per unit to inches and see if it comes out to a better size for you. I understand you are from the UK and Don't use inches but just try it to see if that is the size you want. If it is than you need to re write the gcode so you can make it bigger and still do it in the metric system.

[jalessi]

Youngmasterpete,

One simple solution is to set the scales at 25.4 and run again.

Jeff...

[youngmasterpete]

It depends on the gcode for the road runner. If the gcode is for inches and you are doing it in mm than yes it is going to be to small. You might have to do some editing or switch the steps per unit to inches and see if it comes out to a better size for you. I understand you are from the UK and Don't use inches but just try it to see if that is the size you want. If it is than you need to re write the gcode so you can make it bigger and still do it in the metric system.

Thank you. To make the image larger I had to change my steps per unit so they are no longer 1 unit = 1mm, this. However I had hoped that as I have the mm option selection selected any of the test programs would be automatically reconfigured to be mm values.

As for my step per unit being 43, does this sound correct or is it too small a number?

Perhaps a true test would be to find g-code of a square in mm's cut it and measure it for accuracy.

[youngmasterpete]

thank you jalessi.
That scaled up the job perfectly. Howeverit seems it is now moving at a much slower pace than before, do you know why this might be? Also once scaled the LED's flash yellow, is this just an alert that the job is scaled or does it have another meaning?
Also does a 'step per unit' value of 41 seem far too small? This is what mach3 has calculated my steps to be if i wish to have a 1unit = to 1mm
Forgive me if this questions seem silly but I'm a complete noob at this.

[gtotten89]

you may have to go in to axis calibration and change the acceleration and velocities if you want it to go faster as for steps per unit it is different for different set ups. If yours is working great on 41 or 43 i would leave it there unless you have a problem than you might need to change it, But if everything is coming out within the tolerances you need i dont think it is a problem where you have it set. As for the yellow leds i have not come across those yet myself so i dont know what they mean. You might want to home each axis to see if it goes away. Or maybe since you did the scaling it turned yellow because it is scaled. Just a guess maybe someone else will have more insight as to what it might be.
Good Luck

[UUU]

thank you jalessi.
Also once scaled the LED's flash yellow, is this just an alert that the job is scaled or does it have another meaning?

Yes, it's just an alert that the job is scaled.

[jalessi]

Pete,

Steps per mm is determined by several factors.
See the attached thread:
Rack & Pinion step setup

The flashing yellow indicate the scaling function is enabled.

The roadrunner gcode is inches and the feed rate (F) F60 would be 60 inches (IPM)
However since your Mach3 is setup for mm it is going to run 60mm (MMPM) per minute. You can edit one line in the gcode F60 to what ever feed rate is appropriate for the size cutter and spindle r.p.m. The (S) code is spindle speed. Take some time to learn the basics of gcode.

Jeff...

[ger21]

The roadrunner file is about 7.75x6.5 units. If your machine is setup in mm's, then it'll be 6.5mm x 7.75mm

If you add a G20 to the beginning of the roadrunner file, it will cut it 6.5x7.75 inches.

G20 or G21 in the g-code will cause Mach3 to cut the correct size. If there is no G20 or G21, Mach3 will use the native units.

As you said, the best thing to do is set up the machine in the correct native units, and make sure it cuts the correct size. Once the size is correct, you'll need to adjust the accel and velocity.

[youngmasterpete]

Thank you all for your help and advice. This forum really is great for quick reliable advice.

[dennisbliesner]

Hi
Heres my 2 bobs worth - Native Units should be only set for motor tuning etc and not changed thereafter. G20/G21 set program units to inches/mm. Open ToolPath (Alt 4), regen toolpath and look at Program Limits - this will tell you the dimensions of the pattern. Don't worry about if it is mm or inches, just scale up or down in the ProgramRun (Alt1) window. The yellow blinking bar tells you that the model has been scaled. Return to Program Limits window, regen Tool Path and check redimensioning. Recsale if necessary to get the desired model size.

[youngmasterpete]

I would like to ask for your help and advice again with the current problem i am having with this project.

I have built my CNC machine and have it up and running using Mach3
my machine has a motorized syringe honey dispensing head (see attached image) which I am controlling in the Z axis.

I have a test G-code, which is a spiral. So should create a circle of honey on my machine. However when the cycle starts and the machine runs, there is no visible movement in the Z axis (even though the Z DRO is counting)

I have done the set up steps per unit test and it is correct and the z axis moves fine when jogging.

Any Ideas?

Thanks
pete



G-code im using for test:

%
O5000 (HONEYTEST.TAP)
( MCV-OP ) (14-JUN-2012)
(SUBROUTINES: O2 .. O0)
G90 G17
G80 G49 G40
G54
G91 G28 Z0
G90
M01
N1 M6 T1
(TOOL -1- MILL DIA 6.0 R0. MM )
G90 G00 G40 G54
G43 H1 D31 G0 X-47. Y0. Z0. S1000 M3
M8
(-----------------------)
(F-CONTOUR1-T1 - PROFILE)
(-----------------------)
X-47. Y0. Z0.
G1 Z2. F100
G3 X33.234 Y-33.234 Z-10.75 R47. F33
X-33.234 Y33.234 Z-27.75 R-47.
X-47. Y0. Z-32. R47.
X-47. Y0. I47. J0. F100
G0 Z0.
M30
%

[neilw20]

The file looks and loads OK.
You must have some sort of sticky problem.
Is Z inhibit turned on by any chance?

[youngmasterpete]

Hello again, I would like to ask some advice about my cnc system.

I have purchased an E-stop from worldofcnc.com.

To connect it to my control system I need to wire the 8pin Din connector to two RCA connectors.

I would like to ask if anyone knows how to do this or ink me a tutorial.

Thanks,

Pete