Stepper motors sizes

[loopyloo]

I'm looking at building a 1 to 1.5 metre camera slide for my SLR.
I want the slide to be capable of working in any position from horizontal to vertical.
I've not used a stepper before so I'm after info about 2 things :
1/ What size stepper would I be looking at to lift up to 2Kg ?
2/ What size of toothed belt is going to be strong enough to lift that weight ?

[Gitch]

I'll start with your second question as it'll lead into the first...

Depending on you design, I'd be reluctant to use a toothed belt - personally I would look at using a linear shaft. I think you would get better stability and there would be no chance of belt slippage in the vertical mode. Also I'm pretty sure you can get away with a smaller motor size. As for what size, there is probably a formula that can calculate, but one of those $20 eBay ones could drive my router and hardware easily when I built my CNC.

[loopyloo]

I'll start with your second question as it'll lead into the first...

Depending on you design, I'd be reluctant to use a toothed belt - personally I would look at using a linear shaft. I think you would get better stability and there would be no chance of belt slippage in the vertical mode. Also I'm pretty sure you can get away with a smaller motor size. As for what size, there is probably a formula that can calculate, but one of those $20 eBay ones could drive my router and hardware easily when I built my CNC.

I thought about using a leadscrew but there are advantages and disadvantages.
Firstly it's stronger but heavier and the gearing is very low. With a stepper I can control the speed from extremely slow to fast with full control. With a leadscrew I'd be better off using an ordinary motor for high speed but very low speeds and torque control not possible. If I used an ordinary motor with gearing, high speeds are then not possible.

So those $20 eBay ones you're referring to, do you mean like a NEMA17 or something ?

[gordon_s1942]

An idea.
Model rail makers used a threaded bolt connected directly to the shaft of a small DC motor to drive the blades of a set of points. They connect a bar wth the nut on it to the switch blades so as the bolt spins, the nut now moves left or right.
An other version of this is your pantograph car jack and those screw jacks used to move satellite dishs.

[tristen]

....1/ What size stepper would I be looking at to lift up to 2Kg ?

Go to for that information.

Loopy, for additional background information wander over to cnczone and have a read. It's an extremely good site for the type of advice you are looking for.

An idea.
Model rail makers used a threaded bolt connected directly to the shaft of a small DC motor to drive the blades of a set of points. They connect a bar wth the nut on it to the switch blades so as the bolt spins, the nut now moves left or right.
An other version of this is your pantograph car jack and those screw jacks used to move satellite dishs.

That is called a lead screw and I strongly suspect it is what Gitch meant in his post #2 where he mentions a 'linear shaft'.

To me, the two terms are synonymous.

[Gitch]

That is called a lead screw and I strongly suspect it is what Gitch meant in his post #2 where he mentions a 'linear shaft'.
To me, the two terms are synonymous.

Yep, that is what I meant. Linear Shafts are the slide ones without the screw

[loopyloo]

Go to for that information.

Loopy, for additional background information wander over to cnczone and have a read. It's an extremely good site for the type of advice you are looking for.



That is called a lead screw and I strongly suspect it is what Gitch meant in his post #2 where he mentions a 'linear shaft'.

To me, the two terms are synonymous.

Ok thanks I'll have a look

[loopyloo]

So, another question comes to mind.
What would be the max safe rpm's an average stepper can be driven ? Of course that depends on PSupply and software, but I mean just talking about the stepper.
Maybe a screw would be the way to go. If I could work out which motor to buy it would be easier to set up.
I can get a 10mil screw 1M long and a nut for just over $20. They say the screw is 10x2. No mention of pitch so I can't work out if it's 2 start thread, 2mmm pitch (or 4mm pitch) or what.
It looks like 2 start thread but can't go by the pic cos RS often used generic pictures.
I'd say if I can run the motor at up to around 400 RPM I should get the max travel speed I want.

[Gitch]

The maximum speed of stepper motor is dependant on the motor itself and the controller. For example the NEMA17 style that has 2000 steps per rotation thats just under 13.5k steps per second! Quite a lot and remembering the torque drops significantly the faster the motor rotates, you would also need to consider missing steps and acceleration speeds.

Another consideration would be to use a normal motor, lead screw, and some sort of rotational sensor?

[loopyloo]

The maximum speed of stepper motor is dependant on the motor itself and the controller. For example the NEMA17 style that has 2000 steps per rotation thats just under 13.5k steps per second! Quite a lot and remembering the torque drops significantly the faster the motor rotates, you would also need to consider missing steps and acceleration speeds.

Another consideration would be to use a normal motor, lead screw, and some sort of rotational sensor?

Um,,,,,don't you mean 200 steps ? . 1.8deg per step ?

[Gitch]

Um,,,,,don't you mean 200 steps ? . 1.8deg per step ?

I'll just go into hiding... Yep - the one I was reading the specs on was geared!