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alberto

3-Axis Stepper Controller

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This is a bipolar stepper. This actually has wires to each of the coil ends in your motor. If you have a diagram of your stepper, you will see 4 coils in sets of two. A 6 wire stepper simply has these connected together inside the motor. You will connect the 2 wires at the center of the 2 coil set together, changing it from a 8 wire stepper to a 6 wire stepper motor. Perhaps I have not explained it well. If you still do not understand, I will find some diagrams and post them.
-MP

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I have some bipolar stepper motors that I would like to be able to drive. Where can I get some complete information on the stepper controller that you are discussing? It would fill my requirements I think.

Best regards / Anders Molin

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Hmmmmmmmmmmm I just found the prodject documentation and saw that the driver was for unipolar steppers. These have less tourq than the bipolar if Im not misstaken. Can the driver be used for bipolar steppers or must I find another driver? If so is the case, does anyone know where to find such a driver?

Best regards / Anders the CNC newbii

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In the case that you need higher voltages for a stepper motor, you normally trigger the base of a NPN power transistor and run the higher voltage throught the transistor. The rest of the circuit is just used for triggering and remains the same.

MP

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You can make a clock circuit or basically a pulse generator with a 555 timer so that it sends pulses to the step input of the chip. You can check this with the DIR in either position as this will determine the direction of the motor. This is actually a good pre-test to insure you are not shorting out your PC output board.
The 100V capacitor will work perfect in the place of the one rated at less voltage.

MP

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Would it be possible to manually control the stepping of the controller? I would like to be able to push a button and the motor would do 1 step. I think you would place a N.O. pushbutton switch between the step input of the chip and something else. What would it be?

All comments are appreciated!

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It would be a 4.7K ohm resistor tied to the 5 volt buss.
If the switch is not very good and has a lot of bounce, you might get additional triggering. If this is the case, you will have to add a debounce circuit to the switch, which is just a digital gate and some components around it.

1 step is not much. You might have to put your finger on the shaft of the stepper motor to notice the movement.

MP

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I have found a lot of pictures of engraving machine on the web but no one wich use the 3-Axis Stepper Controller board that we use.

I have some questions:

1)I have three stepper motors with 6 wires:
(red) (red/white) (green) (green/white) (black/orange) (yellow/red)
how to connect them to the board? (1.8 step/

post-30-14279141649736_thumb.jpg

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Alberto, here is an internal diagram of a 6 wire stepper. You can measure the resistance of the different combinations of wires to see which wires go to which coils on your motor. The power supply connects to the center tap of both. When the outside of the coils are grounded one at a time in sequence it causes a step.
To know how much voltage it will handle is usually a part of the numbers stamped on the motor. Most small motors such as this are 5V. If the numbers on the side do not give an obvious clue, you might be able to find the manufacturer's website for the information.

MP

post-555-14279141650315_thumb.jpg

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Hello all!
I am considering building the 3-axis stepper controller - I was able to salvage several Sankyo-Denki stepper motors from old IBM printers, but I'm not sure whether they will work. The motors are rated at 4.1 V, 1.1 A. Assuming I wish to operate a CNC machine in half-step mode, each motor will draw approx. 2 Amperes - with three motors (one for each axis), I think I will need a power supply able to provide at least 6 Amperes *plus* the current requirement for the controller board itself. I am looking for suggestions regarding 1) power supply size (voltage and current), and 2) whether it would be possible to use a simple voltage divider to reduce the motor voltage (the circuit notes indicate that a minimum of 8V must be supplied to the board - dividing this in half should protect the stepper motors from burning out...right? :) Thank you all in advance - sorry for the newbie questions!

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Katsujinsetsunin, perhaps I did not understand your post, but it seemed to me that you will need 2 amp per motor for your CNC requirement but you wish to use steppers rated at 1.1A.
How have you figured the current requirement?
Also, I was trying to find the link to the board you have described which needs 8V minimum. Could you post a link to the project you are building?
BTW - newbie questions are always welcome on this forum.
Please tell us more about your project.

MP

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Thanks for the reply MP - sorry if my post was unclear. This is the link to the CW Technologies stepper board: http://www.electronics-lab.com/projects/pc/008/

The stepper motors are rated at 1.1A (printed on a sticker adhered to the motor housing). I assume this rating is the current per phase, so if I choose to run the motors in half-step mode (activating two coils at once; a higher theoretical torque yield and finer motor resolution at the cost of a higher current requirement). Am I making a stupid mistake by assuming that if the motor requires 1.1A in full step mode, it will require double that (~2A) in half-step?

Regarding the voltage requirement, I am referring to an earlier post by administrator mixos (August 6, 2003) which states:
"The input voltage can be anything from 8V to 35V, but keep it at the voltage that the motor uses and not below 8V."

Hope this cleared up any confusion.

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Hi katsujinsetsunin,
This is the project I thought you might be referring, but I could not find the reference to using 8 volts. I think mixos was talking about the requirements for the 5 volt regulator chip. The mention of 8 volts was so that you had enough voltage for the 7805.

If you are using 4 volt motors and 5 volts for the 5804, you could just use a 5 volt power supply and remove the 7805 from this board. Then drop the supply down by 1 volt for the steppers.

In reference to the current draw and stepping mode:
(Please bear with me as you probably know most of this)
Standard (hybrid) stepping motors have 200 rotor teeth, or 200 full steps per revolution of the motor shaft. Dividing the 200 steps into the 360º's rotation equals a 1.8º full step angle. Normally, full step mode is achieved by energizing "both windings" while reversing the current alternately. Essentially one digital input from the driver is equivalent to one step.

Half step simply means that the motor is rotating at 400 steps per revolution. In this mode, "one winding" is energized and then "two windings" are energized alternately, causing the rotor to rotate at half the distance, or 0.9º's. (The same effect can be achieved by operating in full step mode with a 400 step per revolution motor). Half stepping is a more practical solution in industrial applications. Although it provides slightly "less torque", half step mode reduces the amount of "jumpiness" inherent in running in a full step mode. It does not run faster, just smoother.

So, in conclusion, you will not be using more current in half step mode and you will not have more torque in half step mode. This mode of operation will only smooth out the stepping of the motor.

In regards to the power supply, give yourself some over head. Actually, an old computer power supply is great for running steppers. Linear supplies tend to run warm.

I hope the information is helpful.

MP

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Most production shops use a light oil for cooling and not water since water will cause the parts to rust. However, the answer is yes. You can use one of the switches to be activated whenever the position is not at home. When the switch is activated, you could use this signal from the switch to control a relay to the pump.

MP

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Hello all! After a mishap which resulted in the mysterious burnout of three ICs (subsequently replaced), my controller board finally works :) However, using my software of choice (KCAM), attempting to run the motors in one-phase or half-step mode (by changing jumper position) results in a rather jarring back and forth motion (the motor fails to rotate smoothly in one direction, and instead jumps back and forth, several steps forward, several steps backward, with no net movement) - I doublechecked the solder connections on the controller board and they look alright to me - anyone else have difficulty with this or is this a software specific issue?

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Alberto, the cutting fluid is usually a 8-10% synthetic oil in water (ISO 220 or other water soluble synthetic oil).

You can use a pump operated by a relay connected to a unused pin in the parallel port (from what I see pins 5,14,16,17 are free) and configure your software to activate this pin when the g-code program you are running contains a M8 command. Similarly it should turn it off when reading a M9.

Using the home switches is not a good idea, because if the program calls for a tool change (M6) you are in for a shower...
Of course you could and should have a manuall override, but having the software control the pump is way cooler...

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Dear GreekPic, i think that your idea is wonderfull!! I use to engraving "KellyCam" software and it work good but i'm not very good in electronics! could you help me? Could you drawing a simple electronic schematic?Please.... or explain better your idea? :o

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rschem.gif

More info here:http://www.dakeng.com/relay.htm, in th TurboCNC site.

I have no experienc with KellyCAM, but in TurboCNC in the hardware setup menu you can configure what every pin of the printer port does (step/dir for steppers, home switches, relays etc). Connect the circuit to an unused pin and configure it as the coolant pump in the menu. When the program reads M8 or M9 commands it will make the pin high or low accordingly.

You will also need a splash guard and a way to collect the coolant, filter it and pump it again.

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Or a PNP version which causes the port pin to sink current instead of sourcing it. You can change the voltage and resistor values to suit your current/voltage needs.
I never source current to a relay from a micro or computer port. I always sink. Micros are better at sinking than sourcing.

MP

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