Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: method13 on May 04, 2013, 12:21:23 PM
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Hello everyone,
I have a K2CNC system and I recently added a 4th axis on my own.
I added a G201 Stepper Drive from Gecko drive and a SureStep stepper motor, single shaft, 276 oz-in holding torque, 2.8 amps/phase, 1.8 degrees / full step (200 steps/revolution), NEMA size 23, bipolar
I just setup my 4th axis and it works but now I get noise on my other 3 motors when they move it's almost a grinding noise.
I changed my Step Pulse to 5 from 0 and it got much better but still makes noise.
I created a new profile in Mach 3 for the rotary axis and if I use my old 3 axis profile the motors run quietly.
Any help would be appreciated.
Greg
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Also I'm stumped on how to make the A axis display in degrees, I need to figure out how to make one revolution = 360 deg.
If anyone could help me in this area it would be greatly appreciated.
Greg
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Also I'm stumped on how to make the A axis display in degrees, I need to figure out how to make one revolution = 360 deg.
There is info in the Mach Manual, but, if I recall correctly......
Under General Config> check the box .......A - axis is Angular
The steps per unit should be in degrees in motor tuning for the A axis.
Thus for a 72:1 gear reduction on the rotary and microstepping :
200 steps per one rev of motor X 10 micro steps x 72 gear reduction=144,000 steps per 360 degrees
144000/360 = 400 steps per degree
Play with the Velocity and Accel settings to find motor tuning settings.
RICH
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Excellent thank-you for the help.
Does anyone have any ideas about my first question about the motors?
I read on the forum that motor noise can often be mechanical but I know if I switch profiles and turn off the A axis no noise so I know its not mechanical but it could be electrical?
I used slightly different gauge wire then what was originally used on the rest of the machine wiring could that be it or a bad soldering job?
Just wondering it could be something very simple.
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I have a K2CNC system
There are many... link?
Initial thoughts... power supply... enough amps?
I changed my Step Pulse to 5 from 0
Why?
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Link
K2CNC doesn't sell that machine any more so I have a link to their site through a web archive.
http://web.archive.org/web/20060117044013/http://www.k2cnc.com/CNC-router-KT-2514_detail.asp
I changed my Step Pulse to 5 from 0
Why?
I went digging on this forum for motor noise and I read some one recommend that or it may have been in the tutorial videos.
But the power supply that you mentioned may be correct. I will look into that more.
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So if I don't want to use a gear ratio and want to use direct drive it would be 360 deg / 1.8 deg per step = 200?
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Steps per unit for a rotary axis means steps per degree, so if you do not have any reduction it will be the steps of your motor multiplied by any microstepping you have then divided by 360.
Example would be 200 motor steps per rev x 10 microsteps of stepper drive = 2000 divide that by 360 = 5.5555555 steps per degree.
Hood
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Just a comment if no refuction is used. Resolution decreases thus actual positional accuracy suffers.
At 5.6 steps per degree the approx positional accuracy you could expect would be +- 649 seconds=11 minutes.
11 minutes=0.0033" @ 1" distance & 0.013"@4"
A good way to visualize this would be to shoot at a target at 100 yards , thus you would be at +- 33 inches away from the bullseye.
A handy angular to distance conversion is 1 second = 0.001" at 17 feet.
May not be a concern for you.
RICH
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Thanks for your help guys I really appreciate it.
It was mentioned that it may be my power supply that could be causing the noise on my motors.
What I know so far:
My power supply is 23VDC 300VA
My stepper motor is 2.8 Amps, 3.8mH/phase.
My stepper drive can run between 18VDC and 80VDC.
There is resistors in my router and I'm not sure why they are there.
There are three:
35v 10000uF
63v 330uF
63v 10uF
Any ideas?
Regarding steps per unit how do I find out what my microstepping is?
I read the driver and motor manual I didn't see anything about microstepping.
Thanks again for you help.
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If it is the G201 you mentioned earlier then they have a fixed microstepping of 10, so each rev of a 1.8 degree stepper motor will require 2000 pulses.
Hood
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You can find info on the Gecko site about your G201 drive. You need to set the current on the drive for your stepper by using a resistor.
Step pulse value of 4 should work.
RICH
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The reason I asked why you'd set the step pulse width to 5 in my first post is that you don't need to change it from the default 0 as far as the G201 is concerned.
The 201 steps on the falling edge and its min hold time is 0.5us. The Step Pulse setting in motor tuning is NOT the step pulse width, it's the time you want to ADD to the stock step pulse width that Mach puts out. Art says somewhere in one of his vids that this is between 1 and 2 us - so already 2 to 4 times greater than that needed for the 201.
However - You don't say anything about your BOB (if you use one). Some BOBs have Slooooooow optos and if so these can require longer step pulses from Mach. (one of the reasons I don't use BOBs).
You don't say what the current requirement is of your system BEFORE adding the 4th axis so whether the 4th is taking it over the limit of your PS is not possible to say.
All that said: you say in reply #9 that your power supply is 23Vdc. Chopper drives will not work below a "certain" voltage and the 201's min is 24Vdc so that could well be an issue.
EDIT: forgot to add that your 3.8mH motors "ideal" voltage for torque at speed is 62Vdc so in that respect also your power supply is not a good match.
Ian
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Hello again,
It's been a busy summer but I'm back working on my router again.
I purchased a new power supply; 50V 300VA.
http://www.antekinc.com/details.php?p=696
The problem I'm now having is that I keep blowing fuses on my router.
Where the 110 plugs in there is a little compartment that has a small fuse in it 5A and it keeps blowing.
Any ideas?