[si2030]

Hi Guys,

I am interested in building a linear stepper motor. Its for a linear compressor I want to make.

In simple terms I want to use a linear motor (stepper) to move the piston up and down.

The piston is only 16mm wide and has an anticipated stroke of 16mm hence the stepper motor has to move the piston up16mm and then down 16mm.

I had the idea of placing a couple of coils around the shaft (like a solenoid) and then use a magnet in the shaft.

My problem is that I don't fully understand the stepper motor principle as it applies to a linear situation. I was thinking I could put two or more coils next to each other and perhaps one magnet with N and S at each end.

Could someone assist me with a quick explanation and a configuration that would be precise. The motor should operate at 12 volts and 100 watts.

Kind Regards

Simon

[Mark_T]

Hi Guys,

I am interested in building a linear stepper motor. Its for a linear compressor I want to make.

In simple terms I want to use a linear motor (stepper) to move the piston up and down.

The piston is only 16mm wide and has an anticipated stroke of 16mm hence the stepper motor has to move the piston up16mm and then down 16mm.

I had the idea of placing a couple of coils around the shaft (like a solenoid) and then use a magnet in the shaft.

My problem is that I don't fully understand the stepper motor principle as it applies to a linear situation. I was thinking I could put two or more coils next to each other and perhaps one magnet with N and S at each end.

Could someone assist me with a quick explanation and a configuration that would be precise. The motor should operate at 12 volts and 100 watts.

Kind Regards

Simon

Firstly steppers aren't normally rated by power or voltage, but current and torque. For linear motion you simply buy
a linear actuator using a stepper with a hollow core over the leadscrew, these are standard components (if a little harder
to source than regular steppers).

You say a compressor - that suggests high forces and high speeds which is probably more suited to a linear servo motor.
Do you know the sort of speed and force involved?

Designing/building a truly linear motor would be a major project (whether stepper or brushless servo). You'd need custom
laminations made up for a start. Its far easier to use a leadscrew of some sort.

[mactec54]

si2030

They are quite easy to build, there are different ways to build a linear motor, like what you want to do I don't think a stepper motor would have much to do with it though, a friend has a patent on this type of motor

[Mark_T]

Isn't that just a solenoid?

[dharmic]

No, it's a pump. Solenoid drives the piston, air pressure returns it when current is dropped.

But it would be interesting to know why this kind of thing wouldn't work for the OP.