Stepper Motor Speed

[Gordz]

Yes, drive methodology is important but the OP asked a simple question regarding 1" steppers. Perhaps your desire to share your vast knowledge of stepper motors and the art of driving them is a little much for his query ?

 

[yngndrw]

I don't see how drive methodology does not apply to this question.

Sure the OP has stated that he will be using 1" motors, however he has not set any other limitations - He has simply asked how fast could they spin.

 

[Ubergeek63]

I don't see how drive methodology does not apply to this question.

Sure the OP has stated that he will be using 1" motors, however he has not set any other limitations - He has simply asked how fast could they spin.

Indeed... and the answer is actually quite complicated.

It is one thing in a normal full step resistance limited drive under full load and another with 10x rated voltage available under no load, those being the two extremes.

Some might say 10x is idiotic, but I am going to get a 2.7V 1.8 degree stepper for $8 from Jameco, and it is quite easy to drive it at 10x rating with the $4 A3982 drive chip that they also supply. I figure I can drive it at full load and speed for 20HRs on 8 AAs.

I am actually attempting to make a simple spinner for my wife, the fiber nut. When I get it together and she tries it, she can decide if it was a success or not, for $15 who cares?

 

[diablo1]

Well I'm wanting to rotate a small size motor from rest clockwise 90 degrees, then instantly rotate back to its starting position at 0 degrees counter clock wise. I want to do this about 20 times a second. Is it possible?

 

[Ubergeek63]

far far easier done than said. But it does depend on how much it is trying to move.

Jameco Electronics Electromechanical: JAMECO RELIAPRO: 25BY2407 is very inexpensive and will easily go that fast, but has very low torque. I suspect they all will have very low torque at 1". What are you trying to do?

 

[Gordz]

As Ubergeek63 said, pretty easy to do if there is very little inertia because the smaller motors have low torque. If your motor has a 1.8 degree step then 50 steps will give you 90 degrees, 50 steps per second should be no problem at all but you won't get get instant reversal of direction....

 

[diablo1]

Its going to spin a cylinder that weighs less than 0.05 lbs.

 

[Ubergeek63]

Its going to spin a cylinder that weighs less than 0.05 lbs.

What diameter? It seems like it should but it is getting beyond what I can answer off the top of my head.

Can it, yes, but you might have trouble starting and stopping unless you are going slow. Running at 4x the voltage on a chopper drive should do it. The problem becomes sudden changes in the kinetic energy of the mass, good old Newton. If it is spinning fast, it needs to be stopped before you can reverse it.

Dan

 

[Ubergeek63]

SparkFun Electronics - EasyDriver v3 Stepper Motor Driver

how will that one work?

It is interesting to note that the originator of the circuit (there is a link to it on the sparkfun site) thinks the excessive heat generated by the thing is due to the resistance of the drivers.

Darlingtons do not have resistances, they have saturation voltages. At 0.5A per phase at the IC's typical of Vsat of 2V, we get that the chip dissipates 1W whenever the motor it on. The V3 board has some heat sinking so it might make the 50C/W for 80C die temp in a warm (30C) room. Had he read the spec more closely he might have added schottkys to the board or used an A3977 instead.

Dan

 

[diablo1]

Diameter about 0.70 inches.