mach3, steps & microstepping

[martin54]

Not quite sure the best way to go about setting this up when the time comes so thought it best to ask, the axis on the gerber are belt driven via gearing so how would the best way to set micro stepping & steps in mach3 for each of the axis??
Motors are nema 34 200 steps per revolution.
Any assistance would be much appreciated.

[John S]

Basically boils down to resolution versus speed.
Too much resolution equals slow speed.
Too fast equals notchy resolution.

You can also substitute gearing for micro-stepping which does the same job and if a reduction gearing, like most are, this also increases torque whereas micro stepping reduces torque.

First thing we need to know is how fat the carriage moves for one turn of the motor.

Without this basic information we can't help.

[martin54]

Thanks John, I've got the gantry back on the machine so should be able to measure that, will also take a couple of pictures of the gearing but it is reduction gearing as you say.
Got the user manual but it's pretty hopeless for technical info & can't get any service documents for it as I said in the other thread.

[martin54]

John the X & Y axis are the same size belts & gearing, the Z axis is direct via a screw but I need to remove a cover to see if it's a ballscrew or trapezoidal.

Ten turns of the motor moved the gantry 3 inches for both X & Y axis, ten turns on the Z axis moved it down 2 inches.

Measurements were taken using a ruler so may not be 100% accurate.

8669

[martin54]

Any advice on the best way to start this off now John please. I am guessing I want to set the micro stepping right down on the drivers if the gearing does the same job but is there a way to work out where to start with the steps in mach3.

[John S]

John the X & Y axis are the same size belts & gearing, the Z axis is direct via a screw but I need to remove a cover to see if it's a ballscrew or trapezoidal.

Ten turns of the motor moved the gantry 3 inches for both X & Y axis, ten turns on the Z axis moved it down 2 inches.

Measurements were taken using a ruler so may not be 100% accurate.



Sorry got side tracked, the dog pissed on the carpet and then on my boots when I kicked it up the arse............

OK X and Y ten turns to go 3" so one turn to go 0.300"
200 step motor means each step is 300 / 200 = 0.0015" or a thou and a half per step which is a bit course.
I reckon on a router 1/2 a thou is good enough so you want microstepping of 3 to get 1/2 thou which isn't an available step.

If you choose 5 that gives you 0.0003" per step

Now the Z, 10 turns = 2" so one turn = 0.200"
0.200 / 200 give 1 thou on full steps and 1/2 a thou if you choose 2 micro steps.

That's the maths, you may want different figures.

[martin54]

Will give that a try when I get all the electrics sorted, chears John.

[Jonathan]

You should be able to work it out more accurately by counting the teeth on the gears, so you can work out the ratio. Then count the teeth on the pulley and find out the belt pitch. Post the numbers and we can work it out, if it's not obvious.

[martin54]

You should be able to work it out more accurately by counting the teeth on the gears, so you can work out the ratio. Then count the teeth on the pulley and find out the belt pitch. Post the numbers and we can work it out, if it's not obvious.

That was actually my first thought Jonathan as I had a distant memory of doing something like that donkeys years ago when I could call myself an engineer lol.
Problem is that I didn't think of it before I put it all back together & now it's all sat inside it's little box it's almost impossible to do that so was hoping for an easier way.
If it has to come out again then so be it.

[ptjw7uk]

If you have a dial gauge you can fix it in the router and move the z an amount and see what the gauge says. you could also do the other axis by pushing against the gauge!
Peter

[martin54]

OK so I seem to be just about there now but what I don't understand is just how different my setting seems to be. On the mach3 set up video for motor tuning page they suggest a starting point of about 2000 steps & then the guy actually sets it at 1800. Mine is set now at about 100 which is miles away. Have the micro step on the drives for x & y set at 4. John had said that 3 was a bit coarse so go with 5 on a post above but it doesn't do odd numbers unless you set it through the software & I can't seem to get it to connect to my serial port. z axis is set at 2 on the drive & I can't remember what figure I ended up with for the steps in mach3 but again no where near 2000.