Messages

31

General Mach Discussion / Re: Motor tuning, please take it easy on me I'm new to this :)

« on: August 30, 2019, 04:54:06 PM »

So you you believe 312.5 rpm is far to fast for these motors and at that speed there will be no torque?





[/quote]

Try it and see. I suspect changing the microstepping from 2000 to 1600 will be scarcely noticeable, in fact changing microstepping
to any setting will have no effect on the motors torque at speed.

Craig
[/quote]

32

General Mach Discussion / Re: Motor tuning, please take it easy on me I'm new to this :)

« on: August 30, 2019, 04:29:01 PM »

Looking at both of those motor graphs the torque is very good at rpm's below 500, so surely running at 312rpm will be fine or am I missing something obvious?

33

General Mach Discussion / Re: Motor tuning, please take it easy on me I'm new to this :)

« on: August 30, 2019, 04:21:06 PM »

Hi Joe,

Thanks for the reply and information,

I'm a little lost with what your saying here, your first paragraph says to get 5000 rpmmy motor would spin at 312.5 rpm which your implying i will have next to no torque with these motors at that speed. The next paragraph says with gearing i would be at 625rpm to get the same speed surely there would be no torque left at all then?



"For instance at 2000 mm/min with a 16mm pitch the motor rpm need only be 125 rpm.
To get 5000 mm/min with the same leadscrew the motor rpm is 5000/16=312.5 rpm.

In both cases the required rpms are not high. Would you consider putting a belt or gear reduction or 2:1 in place?
That would effectively make your steppers twice the torque and yet still not require high rpms, 625rpm at 5000mm/min."



What I'm planing to do in the morning is change the stepping to 1/8th 1600 on the drivers and reduce the acceleration from 650 to 250 and see what happens.

What effects will increasing the supply voltage make as it's been mentioned my motors could take 120v rather than the 60v from the current supplies?

34

General Mach Discussion / Motor tuning, please take it easy on me I'm new to this :)

« on: August 29, 2019, 05:44:29 PM »

Hi could I have some advice on my new to me but used CNC router.

I'm very new to Mach3 but have been programming woodworking Cnc's for about 10 years.

Here's the spec and the question,

My machine is approximately 1mtr x 1mtr cutting area with 150mm Z clearence, 3 Axis
2.2kw Chinese water cooled spindle
4 x Nema 34 stepper motor 878 oz.in bipolar Model 34HST9805-37B2 Step Angle 1.8, Rate Voltage 6.4, Rate Current 2A, Phase resistance 3.2,Phase Inductance 15mH
4 x Stepper motor drivers DM860A, PEAK 7.8A , Set to 3.0 RMS Peak 4.2A and 2000 microstep resolution
4x Power Supply  200W-60VDC
Cheap chinese HY-JK02-M 5-axis interface board. ( I'm not enthused with the board now I understand a little bit more about them and at £10 cost it seems penny pinching to run an expensive machine with one)
16mm dia 16mm pitch 4 start thread lead screws on all axis


My Mach3 motor settings are the same for for all three motors

Steps per = 125
Velocity = 2000 mm/min
Acceleration =650 mm/sec
Step Pulse =2
Dir Pulse =2


Kernal speed at 25000 Hz

All that sounds like I know what I'm talking about but I don't

My issue is the axis speed only been at 2000mm, I would like to get to at least 5000 or slightly higher if possible.

I've been informed that it should be possible with the current setup but when I increased just the velocity I got some stalling on the X axis when jogging around.

I've watched many videos and read all sorts of info and it seems motor tuning is an art as well as a science and becuase it's a reflection of the sum of the parts it can differ for everyone.

From what I've gleaned I maybe able to increase the steps per to 200 as that is what my motors are rated at and also that my stepper motor drivers could have been much bigger voltage which would also improve things but I don't how this works, oh and less microsteps?

If anyone can advise with explanations so i can get my head around how it is worked out that would be great thank you.. 

35

Mach4 General Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: August 29, 2019, 05:15:54 PM »

Hi All

Another new member here from the Uk with lots of questions no doubt, here's hoping you're all a helpful bunch

Mark