How much torque requiered for a 3d printer?

[Lord Jon25]

Hello everyone,

I would like to build my very own 3d printer but I have no idea how "strong stepper motors" I actually need. I will be building a 3d printer that has the axes in the same way as "The original Prusa I3 MK3 " 3d printer .I will have extrudor head and the material pusher separated so that motor will not be adding weight to Z axis. The thing that I am concerned is that Z axes will be to heavy for these motors to push up ? Please if anyone knows how would the stepper below act in the printer let me know.

 

Specs of the stepper I would like to buy:

• Manufacturer Part Number: 17HS13-0404S
• Motor Type: Bipolar Stepper
• Step Angle:  1.8 deg
• Holding Torque: 26Ncm(36.8oz.in)
• Rated Current/phase: 0.4A
• Voltage: 12V
• Phase Resistance: 30ohms
• Inductance: 37mH ± 20%(1KHz)

[Hackentosher]

a standard Nema 17 stepper is more than enough for most printer mechanics.

[Lord Jon25]

Okay so you think that I should be fine even though that this motor has only 26 Ncm of holding Torque compared to other nema 17 steppers that have 45 or more ?

[Levent]

here is the thing, on i3 clones the X and Y axis' are moved by belts, if your belts are too lose you will have skipping/layer shifts and you will need to get the belt tense enough that it doesnt skip BUT that would mean you would need a more powerful stepper motor. I honestly wouldnt cheap out on motors, (nor rods or bearings). I actually put together an i3 clone last year using second hand Nema 17s off some dude (and currently using an Anet A8), I would go for that option.

[Lord Jon25]

Thank you for your suggestion. If I understand correctly Anet A8 uses the "Weaker model " of Nema 17 steppers as well ( At least in my opinion, there is no way that they could reach that price point with more powerfull motors, also they look a bit different). If I am correct I should be more worried about moving Z axes ( height) with threaded rods ( that might require more powerfull motors) ? Also the main reason I want to buy these motors is price which I found a deal for 5 motors for only 25 EUR (compared to higher torque ones 40 EUR +)

[Lord Jon25]

I have calculated the torque reqiered for the axes:

 

X and Y axes need 10 N cm of torque ( 5 mm diameter of the gear, friction 0,3, load 2 Kg, 100 mm/s speed, Safety factor 2) 

 

Z axes ( powered by 2 motors ) together they need 17 N cm of Torque ( entire axe in between could weight 1 KG ( extruder + 1 stepper motor, etc.), also Safety factor of 2

 

 

 

Calculated on this website: https://www.orientalmotor.com/motor-sizing/

 

 

I hope that I have calculated things correctly ;)!

[makersmuse]

You'll be fine - the only concern is not the weight on the Z but the force required to alternate directions of the heavy print bed - it might lose steps if you try print too fast. Oh, and you'll probably have to run them pretty hot and with only minor microstepping to get as much usable torque as possible.