I am looking for a fast stepper motor that is accurate and cheap
Seriously, I thought I had what I wanted (an A4988 controller, current limited with high voltage for better speed, and the 4V, 1.2A, 44oz-in motor https://www.pololu.com/catalog/product/1200)
Even though I might have been able to do with a lower torque motor, the 4000 pulse per seconds (1200 rpm) shown in the accompanying graph led me to believe I would get speeds on that order.
Instead, I am looking at around 1/3 of that number. I am using an arduino to send the signals, anything faster than this is stalling the motor with no load. I have a 12 V power supply with about 0.8 A across a single coil.
I will take suggestions as to what models or types of motors I need to look at. Think about 75% the speed of a human playing air hockey, but only needing to move along a single axis, with a very small load to move.
Am I way off base looking at steppers? Or expecting not to spend hundreds for such a device?
There are a few things you could try changing to increase the speed of your stepper motor. First, increasing the motor voltage (while keeping the current limit the same) should allow the current to ramp up faster and let you achieve higher step rates, as discussed in the FAQs for the A4988 carrier. Also, using higher-resolution microstepping might smooth the motor movement and allow it to step faster.
If you want to try a different motor, many of our smaller stepper motors have torque curve graphs that show higher ranges of speeds, although they have less torque. For example, the graph on #1209 goes up to 8000 pps.
Thanks, I havent been able to get the motor spinning any faster, increasing the microstepping hasn’t had any affect.
I guess I am wondering more generally if I am barking up the correct tree… should #1209 give me the change in speed I would need to properly control, for example, an air hockey goalie? Or is a stepper out of the question.
One thing Kevin didn’t mention is that you generally need to ramp up the speed over time (i.e. implement acceleration limiting) if you want to achieve higher step rates. I think the #1209 stepper will be faster than the #1200 stepper, but I expect the maximum achievable step rate to be still be measured in hundreds of RPM. You might want to consider a DC motor with an encoder:
I recommend using a controller with a continuous current limit above your motor’s stall current, just to be safe, so I would suggest the RoboClaw 2x15A over the 2x5A. In our experience, position control with the RoboClaw is pretty rough. Do you need a lot of precision?
It is certainly an option for you to handle the position control yourself by reading the encoder directly with the Arduino, in which case you could use something like our SMC 18v7 or dual VNH5019 motor driver shield. You might be able to get by with our lower-power dual MC33926 motor driver shield, but you would probably want to limit acceleration in software, and you would need to be careful about stalling the motors for a prolonged period of time (stalling motors is generally not good for them, and low-gear ratio motors like the one I recommended are very easy to stall because they don’t generate much torque).
Great I appreciate the tips about RoboClaw controllers.
My project (controlling a foosball rod) will require precision, but its difficult to say exactly how much. I think I will test out the motor you recommend with a high-power controller, and if it isn’t sufficient then I will have to… “manage my expectations”
My only other recommendation is that you carefully consider how much speed and torque you really need before you commit to a motor, or you can buy a few different gear ratios to try out. I think I don’t have a very good sense for what you’re doing, but 1000 RPM seems really fast (and pretty dangerous) for the rotation speed of a foosball rod, and more torque will generally give you more control.
I’m definitely interested in hearing how your project goes, so don’t hesitate to continue asking questions, and please let us know how it turns out!
I have similar problem- needing to turn a propellor in water at 200-1000rpm (low torque ~80mm dia prop) with max efficiency - presently using the 19:1 37mm brushed gearmotor, but it is a bit slow. For max efficiency I was considering swapping to a slow or geared bldc or a fast stepper. Any thoughts on best efficiency for this rpm range? Hard to find a small bldc that runs at this range…thanks
200-1000rpm is very slow for a brushless motor, especially because they’re often used in RC air equipment. The only stuff I’ve seen that runs that slow is a trawling motor (designed for low speed water prop pushing).
I’ve personally also had trouble finding geared brushless motors, so if you do eventually find something, and if you remember, please send me a PM. I’m quite curious.
You can also add your own gearbox to the output shaft of a 2-3k BLDC.
