[7ofclubs]

Help!

I am buildinng my first CNC machine. I decided to put together the electronics first because I am less familiar with it. It would suck to build the machine first and then not be able to get the electronics to work.

The setup:

- Three 6 wire unipolar stepper motors 3.6v 1.2a
- Three kitsrus k179 unipolar stepper motor drivers
- One converted ATX power supply
- One breakout board
- One 5v parallel port protector


The problem: The K179 has the ability to run the steppers internally or externally via the parallel port. At first I had two of the motors hooked up to 5v and seemed to run fine. At first all three hooked up to the 5v worked fine on the internal setting. When I hooked up one of the motors to the parallel port on 5v it got really hot, so I changed the hookup to 3.3v and the motors quit heating up.
Now when I run the motors internally they will run fine for several minutes and then the power supply will quit. When I restart the power supply the motor burps along and will only turn 1.8 degrees and then stop. If I leave the power supply and motors off over night the motors and controllers seem to work fine for several minutes/seconds/or even hours until the power supply stops. Once I restart the supply it all goes to heck again.


Even though I have only hooked up the three motors/controllers to 5v for a brief time I am concerned that I might have damaged the motors or controllers? Is the power supply the problem?

7ofclubs

[plexer]

You should be running the motors at more than 3.3 or 5v I'm suprised they do anything.

The voltage marked on them is now their operating voltage.

There a several threads on this regarding what to run them at so I'm sure a bit of searching will point you in the right direction.

Looking at the pdf for that controller you have bought there are 2 power inputs one 8 - 12vdc for the controller itself and another 5 - 35vdc for the motors so with you adapted psu you are probably looking at feeding 12vdc into both of these inputs.

Ben

[chola]

Hi 7ofclubs,

I'm still pretty new at this as well but hopefully I can offer some kind of intelligent assistance.

Have a look at this site: http://www.oatleyelectronics.com/kits/k142.html

These guys are in Australia, sell pretty much the same kits as you are using (from what I understand), but actually offer some good info in their instructions regarding power supplies, ratings, connections etc. I am running the same kits as you I think, but am powering it through a 13.8v 15amp regulated power supply, with my motors rated at 3.5 volts (for memory) and 3 amps and they run like a champion! I also use a small 12volt dc power supply to power the 'break-out' board as well.

I used the above website for reference when putting my system together and found it very easy to understand, for someone who has had nothing to do with CNC before!

Just to be doubly sure, don't hook the power supply / transformer directly to the motors or you will have issues! Only saying this because I've heard of guys that have done this on very expensive stepper motors and fried them almost instantly!

Hope this is of some help - keep battli'n:cheers:

Colin

[ViperTX]

Well the power supply is the problem.....are you using some software to jog the motors or do the drivers have a mechanism to accomplish that??

[pminmo]

There are several links on my website to help electonics newbee's and steppers: http://pminmo.com/ The discrete board outputs are virtually the same situation as the oakly board you have, so you can also look at those instructions. Also my wiking has some more info: http://www.pminmo.com/wiki/index.php?title=Main_Page

[vladdy]

I've got three of [I think] the same kits on a old MDF mill critter here, and I used an old 24v battery charger transformer on them, work relatively well for what they are, my motors get warm, but not anywheres near uncomfortable to the touch.. did you follow the calculations for the power resistors?

[7ofclubs]

Thanx guys, I appreciate the excellent responses.
I am in the AF and I went to my maintenance shop today and started asking tons of questions. Their consensus is that the ATX power supply that I am using doesn't put out enough watts and I have damaged it somehow. I am going to purchase a 500 watt supply tomorrow and try that one.

7ofclubs

[project5k]

you might think about daisychaning a couple supplies together if you decide that you need more V's... im running 8, yes thats 8 at supplies in series.. (well the 5v lines are in series) so thats 40v out at something like 25A..... and they were almost free.... thiers lots of info on the new about how to do it.. (yes it will require you to open them and make a couple mods...)
so be carefull of thoes big caps... they can bite...

[davurpi]

Hello, my name is David and I know that this thread is old, but is related to it.
I am doing the same project. I just made a draw of connections of K179, with parallel port and with motors. I attach the pdf file with it.

I have these 3 motors to use:
For X and Y axis:
2x PJ80A2-24A. 3.36 Volts Per Phase, 2.0 Amps, 1.68 Ohms Per Phase, Steps 200. (Research-Estimated Torque is .80 Nm / 113 Oz. In. Unipolar Mode).
For Z;
1x 5023-990, 2.3 Volt, 2.3 Amp DC, Steps 200, Hold: 53 Oz. In

I readed on this thread about power supply of motors but I don't understand it: If motors are around 2.3 and 3.3 volts, why people use more, for example, 12 or 15 volt for motors power supply? I think that i need to use one power supply of 3.3v for 2 big motors and other power supply of 2.3v for other motor, isn't it?

At other hand, for KitV i'm thinking on use this usual power supply of 12v 1A. Is good for it?:
Attachment 331652

And please, if possible, say me if you see any mistake on wire connections.

Thank you in advance!
David

Help!

I am buildinng my first CNC machine. I decided to put together the electronics first because I am less familiar with it. It would suck to build the machine first and then not be able to get the electronics to work.

The setup:

- Three 6 wire unipolar stepper motors 3.6v 1.2a
- Three kitsrus k179 unipolar stepper motor drivers
- One converted ATX power supply
- One breakout board
- One 5v parallel port protector


The problem: The K179 has the ability to run the steppers internally or externally via the parallel port. At first I had two of the motors hooked up to 5v and seemed to run fine. At first all three hooked up to the 5v worked fine on the internal setting. When I hooked up one of the motors to the parallel port on 5v it got really hot, so I changed the hookup to 3.3v and the motors quit heating up.
Now when I run the motors internally they will run fine for several minutes and then the power supply will quit. When I restart the power supply the motor burps along and will only turn 1.8 degrees and then stop. If I leave the power supply and motors off over night the motors and controllers seem to work fine for several minutes/seconds/or even hours until the power supply stops. Once I restart the supply it all goes to heck again.


Even though I have only hooked up the three motors/controllers to 5v for a brief time I am concerned that I might have damaged the motors or controllers? Is the power supply the problem?

7ofclubs

[KOC62]

The stepper motors are constant current. It requires a minimum voltage as stated for the motor. The higher motor voltage will allow higher RPM. The motor inductance limits charging current. As the RPM goes up there is a point when the current doesn't doesn't reach the full values. Hence raising the supply voltage causes the current to reach the full value, until this limit is reached and the current drops off again.

[davurpi]

Hello, and thanks for you reply.
Then, there is a minimal voltage to start movement but i suppose that there is a maximum voltage and better don't exceed this value.
But on my stepper mottors, how i can know these values? Or better, what will be the Power Supply that i need to supply the 3 motors as i indicate on wire diagram?
I attach photos of my stepper motors that are:
For X and Y axis:
2x PJ80A2-24A. 3.36 Volts Per Phase, 2.0 Amps,Steps 200
For Z;
1x 5023-990, 2.3 Volt, 2.3 Amp DC, Steps 200

Or perhaps will be better to use the same motor (I have 3 units of the small one) on 3 axis to use a single power suply? But then, what voltage will should be? If will be so, then i will need perhaps a power supply of 2.3 volt and 2.3 (or more) Amp?

Attachment 331656
Attachment 331658
Attachment 331660

And, about the 12v 1A power supply to feed the 3 K179 drive Kit, is good?
Thank you!

[davurpi]

Oh, and another question:
With motors came 2 EMI filters too. I don't know its utility but i imagine that is to motors receive a better power signal. But i use 3 motors and i only have 2 filters. I have to connect its? how i have to connect? I never did it and i newer listen about EMI filters. I'm new on electronics. I attach a photo:
Attachment 331662
Thank you!

[tommylight]

Oh, and another question:
With motors came 2 EMI filters too. I don't know its utility but i imagine that is to motors receive a better power signal. But i use 3 motors and i only have 2 filters. I have to connect its? how i have to connect? I never did it and i newer listen about EMI filters. I'm new on electronics. I attach a photo:
Attachment 331662
Thank you!

NO, not for the motors, that is for mains interference filtering.
Do not connect that to motors. Does not have anything to do with motors.

[KOC62]

The filter is for connecting between your AC line and your power supply. Some power supplies may have them built-in. So you would only need one as you can drive 3 steppers from one DC power supply.
Geckdrive dot com uses a formula to calculate the maximum motor voltage. It is 32 * SQR(motor inductance in mH). Lets say your motor has 1.25mH inductance then the maximum rule of thumb is 32 * SQR(1.25) = 35.77VDC. Source: G201 REV-16 - Stepper Drives - Motor Control Manuals - Support | Step Motor Controls
The inductance is obtained from the motor manufacture. It's not printed on your motor pictures. Also the inductance can change depending on whether it is connected as bipolar or unipolar. Bipolar uses 4 wires and unipolar uses 6 wires. There may be other variations. Data sheets are the best way to know.
I didn't find a spec for your "PJ80A2-24A" motors.
The other motor number came up with this - http://www.alltronics.com/mas_assets/acrobat/25M002.pdf
This one has a schematic for driver and uses 40VDC for power supply. this motor has 6 leads.
You can start with a 24VDC power supply with say 6A or better current rating. Each motor needs to have its current limited to its rated current by the driver.

[george4657]

The K179 driver has no current limiting so using voltage over the rated voltage will overheat the motors.
You will need to put resistors in line with each center tap (2 per motor)
See this link in how to calculate value of resistor. Stepper motor help (very hot!)

When viewing info on steppers remember that these are unipolar drivers and most modern drivers are bipolar ( 4 wire )
Also this driver is single step only where modern ones are 16 step or greater so resolution will be much lower.

[davurpi]

Then is convenient to use this filters to the main circuit? Is needed for functionality or to reduce a big risk or is only optional?

NO, not for the motors, that is for mains interference filtering.
Do not connect that to motors. Does not have anything to do with motors.

[davurpi]

Ok, thanks for the info about add the resistors.
Then, i understand that i can use a 12v power supply if i use a resistor with a resistance value to low this voltage to motor voltage (2.3v). Isn't it?
Then, if my motor if 2.3 volt and is 2.3 A, then the Resistance value will be: R = E /I (12V -2.3V)/2.3A = 4.22Ω
And for the bigger motor that is 3.36 Volts and 2.0 Amps then, R = E /I (12V -3.36V) / 2A = 4.32Ω

Is it correct?
Thank you!
David

[KOC62]

Then is convenient to use this filters to the main circuit? Is needed for functionality or to reduce a big risk or is only optional?

It is to reduce power line noise (EMI) from entering or exiting your system. It is optional, but more like insurance in that "junk signals" don't get in or out.

[KOC62]

Ok, thanks for the info about add the resistors.
Then, i understand that i can use a 12v power supply if i use a resistor with a resistance value to low this voltage to motor voltage (2.3v). Isn't it?
Then, if my motor if 2.3 volt and is 2.3 A, then the Resistance value will be: R = E /I (12V -2.3V)/2.3A = 4.22Ω
And for the bigger motor that is 3.36 Volts and 2.0 Amps then, R = E /I (12V -3.36V) / 2A = 4.32Ω

Is it correct?
Thank you!
David

Math wise yes. Don't forget to calculate the resistors power consumption. Get a resistor power rating that is 25% higher than what you are dissipating.

Your controller is primitive, and inefficient due to adding the series resistor. It also may have that resonant range where the motor stalls.in a certain RPM range.
I would suggest getting a more efficient driver that has a chopper feature to control motor current. I use a Gecko G540 as an example. There are other options by members on this forum.

[davurpi]

Ok thanks, and about you said me that there is a voltage to start movement and other higher when running fast, then, the 2.3V of the label what of both is?
Because perhaps is better to use another voltage to calculate resistance instead the labeled voltage of motors...

Thanks!
David

Math wise yes. Don't forget to calculate the resistors power consumption. Get a resistor power rating that is 25% higher than what you are dissipating.

Your controller is primitive, and inefficient due to adding the series resistor. It also may have that resonant range where the motor stalls.in a certain RPM range.
I would suggest getting a more efficient driver that has a chopper feature to control motor current. I use a Gecko G540 as an example. There are other options by members on this forum.