Suitable stepper motor for CNC

[Raul PadillaParticipant @raulpadilla54684]

Hi all,

It's about time I got out of the dark ages when it comes to drilling my boards and I wish to build a CNC machine. While I understand how the drill info is sent to the machine which steps motors to get to the right place I am unsure about which motor to go.

Just about in every project I have seen the large square stepper motors but I saw these:

 

Are these acceptable for a small light weight machine? I know that torque might be an issue which is why I would make the axis and table as light weight as possible. Could these be used?

All the best,
Robin

Edited By Neil Wyatt on 11/03/2020 10:48:30

[Raul PadillaParticipant @raulpadilla54684]

[EmgeeParticipant @emgee]

Hi Raul

Your picture or link did not show.
The size of stepper motor will depend on the weight of the table to be moved and the friction of the sliding parts, there are calculations for determining the torque required to do the work required.

NEMA 23 size steppers would be powerful enough for what I consider a small lightweight table, they are available in a range of torque outputs and can be driven by low cost controllers.
FYI the 23 size is 2.3"

Emgee

[Ronald MorrisonParticipant @ronaldmorrison29248]

Stepper motors are listed by size and by the torque they produce. Size matters for the space you have for mounting them. Torque matters as that is what determines whether the motor can turn the load. I've chosen motors that have a little less torque than I wanted for the project but I had sufficient room to offset the motor and use a timing belt. That allowed me to put a 20 tooth pulley on the motor and a 40 tooth pulley on the shaft giving me nearly double the torque (minus a little belt loss) but cuts the maximum speed in half. Estimate the required torque and speed and then choose the motor that fits the space and fits the other requirements.

[The Novice EngineerParticipant @thenoviceengineer]

Raul

You have posed an open ended question with few details [ as the link in your post failed !} , there are lots of choices to make before considering stepper size.

The choice of what size motor depends on the design of the frame, the load they have to move and the speed you want get the Drilling head/Work Table to travel at. Higher speeds also need more torque, either a longer stepper motor body, higher running voltage or moving up to a larger frame size.

For example using a Dremel style Drill Body in a Prusa style 3D printer chassis, this light weight design might be what you are considering

3D Printer frame as CNC PCB Drill using NEMA 17 steppers

To give you an idea of what motors I have in the various machines

Emco PC50 milling machine uses NEMA 23 frame size stepper motors 76mm long. XY Table Assy weight ~15kg Running at 24Volt

A large 3D printer uses NEMA 17 35mm long. Print Head Assy ~ 0.75 kg Running at 24 v

Laser Engraver uses NEMA17 24mm long Laser Head Assy ~0.25kg Running at 12v

Steve

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