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This is a follow up to the Easy to Build Desk Top 3 Axis CNC Milling Machine Once you get the machine all put together its time to make it go.
So it's time to drive the motors. And here I've put together a circuit that I think is the absolute cheapest and easiest way to control stepper motors with step and direction signals. It works with many of the free or low cost softwares that produce step and direction signals through the parallel printer port. I'll explain how it works but for those of you who just want to get on with it... The_Next_Step
But I would suggest for those of you who are unfamiliar with circuits to do it on a bread board (see pictures). This way you can easly correct any mistakes and try different things.
This schematic is just to control one motor so for the milling machine you need 3 of these circuits and 3 motors.
From Left to right and top to bottom. I try to draw schematics so that positive voltages are toward the top and ground or negative volge is toward the bottom. Inputs are to the left and outputs to the right. Fist off the voltage that you are going to use to run the motor needs to be stepped down and regulated for the logic chips. I used a 6.2 volt Zener to do this because it's low enought for the logic chips to receive the signals from your printer port and high enough for the outputs to drive many of the standard power FETs, so you may not have to use logic FETs like the schematic shows. So the resistor R1 drops the voltage, the Zener diode regulates it to 6.2 volts and the capacitor C1 filters out any noise from the motor, and this voltage powers the two IC's.
The first IC (CD4516) is called an up/down counter. One signal from the printer port will tell the counter if it will count up or down and the other signal, called step, will increment or decrement the counter by one count. Now were only going to use two outputs from the counter Q1 and Q2. With this binary counting method there are only 4 combinations of output from the counter: 00, 01, 10, and 11. These lines are fed to the A and B inputs of the other IC (CD4028) which decodes these combinations to 4 seprate outputs.
I did a trick here using the C input to work as an Enable input. If the Enable(optional) is connected to the parallel port and the computor tells it to shut off all of the outputs to the FETs will go low(Off). So the four outputs of the decoder drive the FET transistors and the FETs drive the four poles of the motor.
Now everybody wants to know what the light bulb is for. Its not so much whether you use a bulb or a resistor, its that a bulb comes with a socket. You can get these wedge base light bulbs from 1 watt to 20 watts. Start with may be a 4 watt bulb and if you find you need a little more beef you just pull it out and put in a 10 watt bulb. It's really handy. And I found it's good to have some voltage drop there as kind of a ballast for the motor windings. The diodes catch some of the current that comes out of the motor each time the FET transistors turn off. The diode feeds this current back to the supply.
When you get the circuit up and running find a power supply that puts out more voltage than you really need and then change out light bulbs till you get it running smoothly. Some of my stepper motors are 5 or 6 volt and some are 12 volt but it all works out.
So it's time to drive the motors. And here I've put together a circuit that I think is the absolute cheapest and easiest way to control stepper motors with step and direction signals. It works with many of the free or low cost softwares that produce step and direction signals through the parallel printer port. I'll explain how it works but for those of you who just want to get on with it... The_Next_Step
But I would suggest for those of you who are unfamiliar with circuits to do it on a bread board (see pictures). This way you can easly correct any mistakes and try different things.
This schematic is just to control one motor so for the milling machine you need 3 of these circuits and 3 motors.
From Left to right and top to bottom. I try to draw schematics so that positive voltages are toward the top and ground or negative volge is toward the bottom. Inputs are to the left and outputs to the right. Fist off the voltage that you are going to use to run the motor needs to be stepped down and regulated for the logic chips. I used a 6.2 volt Zener to do this because it's low enought for the logic chips to receive the signals from your printer port and high enough for the outputs to drive many of the standard power FETs, so you may not have to use logic FETs like the schematic shows. So the resistor R1 drops the voltage, the Zener diode regulates it to 6.2 volts and the capacitor C1 filters out any noise from the motor, and this voltage powers the two IC's.
The first IC (CD4516) is called an up/down counter. One signal from the printer port will tell the counter if it will count up or down and the other signal, called step, will increment or decrement the counter by one count. Now were only going to use two outputs from the counter Q1 and Q2. With this binary counting method there are only 4 combinations of output from the counter: 00, 01, 10, and 11. These lines are fed to the A and B inputs of the other IC (CD4028) which decodes these combinations to 4 seprate outputs.
I did a trick here using the C input to work as an Enable input. If the Enable(optional) is connected to the parallel port and the computor tells it to shut off all of the outputs to the FETs will go low(Off). So the four outputs of the decoder drive the FET transistors and the FETs drive the four poles of the motor.
Now everybody wants to know what the light bulb is for. Its not so much whether you use a bulb or a resistor, its that a bulb comes with a socket. You can get these wedge base light bulbs from 1 watt to 20 watts. Start with may be a 4 watt bulb and if you find you need a little more beef you just pull it out and put in a 10 watt bulb. It's really handy. And I found it's good to have some voltage drop there as kind of a ballast for the motor windings. The diodes catch some of the current that comes out of the motor each time the FET transistors turn off. The diode feeds this current back to the supply.
When you get the circuit up and running find a power supply that puts out more voltage than you really need and then change out light bulbs till you get it running smoothly. Some of my stepper motors are 5 or 6 volt and some are 12 volt but it all works out.
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Signing UpStep 1The Circuit Board of Appeals
OK here's what your all looking for. I made a simple PC board layout that includes 3 motor driver circuits connected to a 25 pin D sub Parallel printer port connector. Here's a picture of the layout. At the top of the picture you see a place for a voltage regulator. You can use that or you can put a resistor and Zener Diode in its place(like the schematic shows). On the right edge is a place for the 25 pin D-sub connector that connects to the parallel printer port. You just jam the PC board between the two rows of pins and solder it.
On the left side are places for the lamp sockets. You need to look over the schematic to see where some of the parts go but it's all there.
On the left side are places for the lamp sockets. You need to look over the schematic to see where some of the parts go but it's all there.
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I was wondering how many Amps could I draw from this circuit powered by how many volts ?
Thanks!
Thanks Carl
spec of motor?
John
http://www.youtube.com/watch?v=cgbeyNNBZ68
I don't use Mach though I run EMC2 http://www.linuxcnc.org/index.php
I am puzzled though, why don't you use voltage shifting transistors at the Step, Direction and if used, Enable inputs so that the entire circuit runs at full voltage, deleting the zener. The ICs are rated at 20 volts. Most fets need higher gate voltage to drive to saturation, (except the logic level parts you specify - but logic level fets I have found are much more expensive) and a couple of level shifter transistors at those inputs would be very cheap - maybe a few pennies.
Anyway, like I said, I plan on building your circuit as my first foray into CNC and I ordered parts to build this, and I'll try what I suggest too, see how it goes. Just curious if you had already considered that option and discarded the idea for some reason I don't see.
I have a question. Can I run this circuit on 3V? because i have 3 3V 2.1A stepper motors. I'm scared of burning them by running at 12V.
Please, help me with something here?
I want to build a CNC mill because my actual project is building a guitar so, for a neck that is about 26 in x 3 in x 2 in; and the soundboard around 15 in x 20 in x 3 mm should I shop for a larger or stronger or faster motor; how large? does it need to be a stepper motor or any motor would do the job?
And the other question is what software do you use and if it is mac compatible?
Thanks,
Jack
so everything appears to be in the correct place
the lights come on when i add power
everything is fine then after the computer gets past bios the lights switch off!
if i take the paralel out they all come back on again!!
any idea what i have done wrong?
and yay i now have one axis working woowoo!!
Thanx for this circuit! It's been quite a chalenge for me to get it to work properly but now I've finally got it to work. First I build it on a breadboard and now it's on a protoboard, the first axis done now, yey!
Further more, I have the same question as Kodex, what kind of resistor do I need if I want to replace the lightbulb. All the resistors, with the +/- same resistance as the lightbulb i've been using, I tried so far are getting very hot during use...
Tom, Anyone...?
Greets,
Wire
If I would like to replace the bulb with a resistor, how determine the ohms I need and the wattage it should handle?
Thanks,
Steve
wat is d fact?
Firstly, I would like to say, that this tutorial is amaizing. Thank you for doing this.
But, I have a problem. I am using stepper motor stp-42d221-03 and I cant figure out, how to connect it with board. It has only 5 wires and all of them are grey (only first one has blue stripe). Please help. I tried connecting it about 100 times and it always goes few steps (about 5-10 depends on wire order) forward and few steps backward (about 2). I need help.
Thanks
Paul
start with this webpage and work forward
thanks
adam
if you need any help message me
you are correct on where the direction, step, and enable need to be.
to do a quick test unplug from computer. make your enable wire HIGH. make your direction wire HIGH or LOW. take a wire from your clock and move it from GROUND to VDD to GROUND......
everytime you touch VDD your stepper should move one step. change the direction wire and try it again. then ground your enable wire. if it stops power to the motor. if all that works everything is working onthe circuit side of the cnc driver.
i have not used mach3 yet but when i do ill let you know if anything needs changed. as far a kcam it works perfectly. just set up the port and the table settings and its works good. i cant seem to get it to run off of g code. only .gc files will work for some reason.
good luck
Tried steps above and unfortunately, motor no move, must be something wrong, I just don't where?
I have a question / Pin No.1 in lpt Running A Drill to Start ?
thanks for this great instructable. However, I have a question according the IC CD4516. Can I also use a different IC instead f the CD4516 because this particular IC is not aviable in my country.
Thanks
i was suggested by my local vendor to use the 12n60 mosfet instead of the 12n10 as given...
now iv built the circuit, the motors power up on 2 axis but dont respond to KCam.
so is it because of the mosfets?
- also the bulb of the driver in the centre doesnt even light up...iv checked the circuit, nothing seems wrong..
suggestions pls?
Thanks and congrats ! ;-)
Jorge L.
Again I need help from the masters here.
I confess I'm lost! Do not know, what may be happening.
All 16 pins are having signal. The other pins 1-4-6-7 CD4028be, do not change status by clicking on the arrows.
Sometimes clicking on the arrows to hear the engine noise of contact very short.
List of board components:
CD4516BE
TC4028BP
K2391 (FET)
7806A
Lamp (i think is 18 volts or +)
Help me please, Thanks!
Damien
Im in the same situation as Damienb and i don't have a parallel connection on my laptop. I'm looking at getting a parallel port expresscard and i wonder will it suffice and provide the correct voltage for the steppers?
Cheers and thanks.