What is the cheapest option to drive a single axis?

[Apples]

What is the cheapest option to drive a single axis?

So I'm talking about the stepper, driver, power supply and computer software. Rather then spending more cash than what is needed. What is the cheapest way to drive a single axis?

I could use a dc motor with one of those speed controllers, then I could just have a knob to adjust the speed. But...If I could use EMC (free) then I could each time exactly set a desired travel speed and increase and decrease by increments etc.

So what is there out there to do it the cheapest way. Only moving a small load 2lb at a slow speed.

Peter

[krak]

How much work do you want to do? You could go very cheap if you are willing to do some work. EG buy an Arduino and a motor shield, tear apart an old printer and bingo. You’ll have everything you need. Arduino has some very rough Gcode interpreters. But it can also be programmed to do very repeatable operations from inputs or coms from the main computer. This could be done for about 100 bucks.

[Apples]

Yeah I guess that could work.. Isn't there also something called the PIXAXE.. Or is this old stuff now?

Would it be able to run a stepper big enough to turn a acme rod for motion?
What about hobbycnc, I think their board is for 3 axis. I there a single axis board? Cheaper?

Peter

[underthetire]

Originally Posted by krak How much work do you want to do? You could go very cheap if you are willing to do some work. EG buy an Arduino and a motor shield, tear apart an old printer and bingo. You’ll have everything you need. Arduino has some very rough Gcode interpreters. But it can also be programmed to do very repeatable operations from inputs or coms from the main computer. This could be done for about 100 bucks.

I agree 100%. That is by far the cheapest way to drive a single, or even 2 axis. I bought my Arduino Delemova on Ebay for 10 bucks, with a LCD keyshield. You can also pick up a cheap high torque model servo from King Hobby for less than 20. They even have a Servo driver for 10 bucks if it would work for your application.

[krak]

PIXAXE is another type of micro controller. It is pretty popular with hobby robotics groups. I think it is based on Visual basic programming, where the Arduino is based on C programming. ( NOTE: the arduino is open sourced and you can built it yourself off of plans.)

The motor shield can handle a decent amount of amperage, but you might want to gear it down if you are using a stepper motor out of a printer. Your next best option, IMO, is a Gecko drive. Maybe a G250 for about 60 usd., or the G251 for for about 70 usd. You’ll also need a powersupply, a motor, and a computer to control it.

What is included in your project? What is it you are trying to work with? I might be able to offer more reasonable solutions with more details of the task at hand.

these links might help
http://www.sparkfun.com/commerce/pro...oducts_id=9402

http://reprap.org/wiki/Stepper_Motor_Driver_1.1

http://www.adafruit.com/index.php?ma...products_id=81

[Apples]

I don't mind getting out the soldering iron and putting all the bits together.

I just want to move a welding torch forwards and backwards so that I can get accurate speeds etc , and constant speeds. That's why instead of using a dc motor speed controller, It would be nice to be able to punch in a travel speed and have the stepper/liner slide move at a known speed.
If I was just a motor speed controller I would have no way of knowing what speed it is going at, unless I was to time how long it took to get there etc. What about hooking up a encoder? Would that be able to give me a speed readout? if using a simple DC speed controlled motor?

[krak]

Ok, I think I understand what you are trying to do. I have a backround in PLC programming and learning a few different mirco controllers. With that said, I believe you would be able to drive a torch at a constant speed with a program fairly simply. Provided you had a sound mechanical device, meaning the drive will not hang up an anything, you would not need an encoder or some other way of making it a closed loop system. At this point I would still recommend an Ardiuno. It can be set up to run either a Stepper motor or DC motor. The motor shield can be upgraded from the plans to handle higher amps. I don’t think it would be too hard to find help on the internet to make those upgrades. A stepper motor will give you much more control on the accel / deccel rates of the torch moving forward or backwards. I am envisioning an Oxy torch rather than a Mig. Preheating the metal maybe? Anyway the Ardiuno can be programmed with speed control and speed changing in mind. Counting the steps will ensure you stay wit in your range. I’m not sure how I setup a simple dc speed controller to handle both ramp speeds , and reversing direction in way that would be very repeatable.

[Apples]

Righto I will start researching the Ardiuno then.

[Apples]

Well I have a look and looks like I'm back over here now as I need to run about 2-3amp steppers and the arduino can't do that.

I'm looking at the HobbyCNC board only $64, like how I would not have to get a breakout board like I would If I used a gecko drive G251 etc.

I really do not need 3-4 axis only the 1..

[krak]

Originally Posted by Apples Well I have a look and looks like I'm back over here now as I need to run about 2-3amp steppers and the arduino can't do that. I'm looking at the HobbyCNC board only $64, like how I would not have to get a breakout board like I would If I used a gecko drive G251 etc. I really do not need 3-4 axis only the 1..

The Arduino would provide the step and direction pulses. The motor shield would send the power to the motor. An Arduino and a gecko driver might be a good combo for you.

[H.O]

Hi,
Technically you don't have to use a breakoutboard. The breakoutboard provides a convinent way for you to interface between the LPT-port and other devices, they usually also provide galvanic isolation which is a big selling point but not strictly needed. Simply cut the end of a LPT-port cable, figure out which wires go to the pins you need and connect them to the drive.

If you don't count the PC on which you'd run either EMC2 or Mach3 (Mach3 isn't free but for your purposes the demo version will be more than enough) all you need is a motor driver, a powersupply and your motor.

If you count the PC then an Arduino is cheaper but then you need to learn how to program it, getting acceleration and deceleration algorithms sorted (if you're not running the motor VERY slow) figure out a suitable way to key on your settings like distance to move, speed etc. It's nothing wrong with that and it may be cheap but before you have something working you've spent a lot of time.

I don't know that much but Arduino, they may have libraries for this kind of thing but if you're not familiar with microcontroller and programming it will be a learning curve never the less.

You could build the drive too if you want to, the old L297/298 combo is good for ~2A and some Alegro chips are capable of more than that. But again, before you have something working you've spent a lot of time and probably a lot more cash in "development" cost than a what a say a G251 costs.

There are several small step-motor "modules" available from places like Pololu but they generally can't handle current in the range of 2-3A.

I have no experience with the HobbyCNC board but 3 axis for $79 sounds like a bargain. You get the one axis you need and two spares. It's unipolar which is a bit "old technology" but it is a chopper drive. As long as it works I'm sure it'll suffice for your purposes.

/Henrik.

[krak]

H.O. is right there will be a learning curve to use the Arduino. Since I had the back ground with PLC’s and types of programming, it did not take me very long to pick up it. It took me longer to get up to speed with Mach. I’m still learning it. I have found that there a number of libraries for using a stepper. In these set ups you simply supply the number of steps, or a formula to determine steps for known distance. Factory in the max speed, and it handles the rest. However the gcode would be very simple as well figure out your feed rate, plug in the start and finish back to start and repeat. So how much is your time worth? Is it worth it to you to learn something new? How much would you value the new lessons?