CNC Electronics Problem(s)

[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

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...