<p>The size of the stepper is usually determined by the forces it must overcome on the machine (i.e. inertia). Obtaining a powerful stepper motor and then using expensive linear guide rails with high tolerances great axial rigidity is wasteful unless you are trying to achieve something specific (which it seems you are not).</p>
<p>Find the cheapest NEMA17 motor you can from a reputable site and start there.</p>
<p>Most of the work has been done for machines of that size, so you don't need to calculate what's required, you can just look it up online. A 250W @ 24V supply is commonly used on printers of that size. The majority of that power is going into the heated bed. If, however, your environment is so cold that the bed never gets to temp, no matter how long you wait, then it will be time to upgrade that bed to an AC mains heated one.</p>

CC BY-SA 4.0
2021-01-08T14:55:52.213Z
Hi, really thanks for your answer ❤️ I am not using a het bed as I am trying to make it as cheap as possible, and a het bed will also need a more powerful power supply which will increase the size. So, are you in short saying, a 2.5kg.cm motor is useable as it is the most reasonably priced and cheap motor from amazon
Leo Red
CC BY-SA 4.0
2021-01-08T17:18:25.550Z
Hello Leo, For a small 3d printer that should be enough. The torque output on the stepper is directly proportional to the power that you put in, without it melting.
user77232
CC BY-SA 4.0
2021-01-09T04:21:26.293Z
Thanks again ❤️ Would giving the power recommend by the seller be ok? I am really worried about the z-axis, will 2.5kg be ok? And also, is 20x20x20 really small for basic use? As, I used a rular to visualise the print volume, and it look small to me (Most likely because I haven't seen a 3D printer in real life as they are really expensive in my area) I am mostly only going to use it for electronics and robotics project that are not very big. Sorry for asking many repetitive questions, I was not able to find answers to these specific questions 
Leo Red
CC BY-SA 4.0
2021-01-10T08:52:28.893Z
You can exceed the voltage since the stepper driver will be proving the current via PWM, it should be fine. Better buy some spares just in case. If the motor gets too hot too quickly then turn down the power in the firmware's configuration.
user77232
CC BY-SA 4.0
2021-01-08T14:41:54.410Z
2021-01-08T14:41:54.410Z
user77232
<p>I am making a DIY 3D printer and I need to know which stepper motor I should use. I am planning on making an 18x18x18 or 20x20x20 max print size. I am only using a single Z-axis like the Prusa Mini. I am planning on using 1.75 mm filament.</p>
<p>Which stepper motor should I use for my X-, Y-, and Z-axes and the extruder?  How do I calculate the power needed? Will 2.8 kg or something near it be enough?</p>

CC BY-SA 4.0
2021-01-06T20:14:22.630Z
Welcome Leo! you don't need strong stepper motors, I've have made my own with motors like yours. I hope someone else can answer with calculations your question.
Fernando Baltazar
CC BY-SA 4.0
2021-01-07T03:16:48.327Z
Thanks, will 2.5kg.cm steppers work for the x, y, z axis? I forgot to tell, I am using a Bowden extruder to keep the weight on the axis low. Also, can you share which steppers you are using and maybe also a photo of it ☺️
Leo Red
CC BY-SA 4.0
2021-01-08T11:02:27.470Z
Hi, I checked the prusa mini's github page to find which stepper motor it uses (As mine is inspired and based on it), and it uses 5kg.cm motor! (If I am reading it right), Which is really expensive in my area. So, can I use 2.5kg.cm motors I am planning on using? Yes, my axis(s) will be light weight and will also have secondary supports. Here is the link to the spec sheet: https://github.com/prusa3d/Original-Prusa-MINI/blob/master/DOCUMENTATION/ELECTRONICS/mini-motor-kit.pdf
Leo Red
CC BY-SA 4.0
2021-01-08T19:01:11.577Z
Right! 5K motors are better in a bowden extruder but 2.5K will work, I have 2 printers, just be sure to keep extruder temperature above 190°C while extruding.
Fernando Baltazar
CC BY-SA 4.0
2021-01-09T04:17:39.023Z
Oh, Thanks ❤️ I didn't think I can use a 2.5kg one for the extruder. It is going reduce the price alot! Thanks
Leo Red
CC BY-SA 4.0
2023-12-08T12:45:44.043Z
Am I the only one not understanding what size is meant? `18x18x18 or 20x20x20 max print size`; is this in mm, cm, inches? Considering the use of other SI units I would assume the size is expressed in cm.
0scar
<diy-3d-printer><stepper><prusa-mini>
How to choose a stepper motor when building a DIY 3D printer?
Leo Red
# How to choose a stepper motor when building a DIY 3D printer?

(Asked by: username_0 on 2021-01-06)

I am making a DIY 3D printer and I need to know which stepper motor I should use. I am planning on making an 18x18x18 or 20x20x20 max print size. I am only using a single Z-axis like the Prusa Mini. I am planning on using 1.75 mm filament.

Which stepper motor should I use for my X-, Y-, and Z-axes and the extruder? How do I calculate the power needed? Will 2.8 kg or something near it be enough?

**Tags:** diy-3d-printer, stepper, prusa-mini
> **Comments:**
> **username_1**: Welcome Leo! you don't need strong stepper motors, I've have made my own with motors like yours. I hope someone else can answer with calculations your question.  
> **username_0**: Thanks, will 2.5kg.cm steppers work for the x, y, z axis? I forgot to tell, I am using a Bowden extruder to keep the weight on the axis low. Also, can you share which steppers you are using and maybe also a photo of it ☺️  
> **username_0**: Hi, I checked the prusa mini's github page to find which stepper motor it uses (As mine is inspired and based on it), and it uses 5kg.cm motor! (If I am reading it right), Which is really expensive in my area. So, can I use 2.5kg.cm motors I am planning on using? Yes, my axis(s) will be light weight and will also have secondary supports. Here is the link to the spec sheet: https://github.com/prusa3d/Original-Prusa-MINI/blob/master/DOCUMENTATION/ELECTRONICS/mini-motor-kit.pdf  
> **username_1**: Right! 5K motors are better in a bowden extruder but 2.5K will work, I have 2 printers, just be sure to keep extruder temperature above 190°C while extruding.  
> **username_0**: Oh, Thanks ❤️ I didn't think I can use a 2.5kg one for the extruder. It is going reduce the price alot! Thanks  
> **username_2**: Am I the only one not understanding what size is meant? `18x18x18 or 20x20x20 max print size`; is this in mm, cm, inches? Considering the use of other SI units I would assume the size is expressed in cm.  

---

## 1 answers

### Answer by username_3 on 2021-01-08. Score: 2

The size of the stepper is usually determined by the forces it must overcome on the machine (i.e. inertia). Obtaining a powerful stepper motor and then using expensive linear guide rails with high tolerances great axial rigidity is wasteful unless you are trying to achieve something specific (which it seems you are not).

Find the cheapest NEMA17 motor you can from a reputable site and start there.

Most of the work has been done for machines of that size, so you don't need to calculate what's required, you can just look it up online. A 250W @ 24V supply is commonly used on printers of that size. The majority of that power is going into the heated bed. If, however, your environment is so cold that the bed never gets to temp, no matter how long you wait, then it will be time to upgrade that bed to an AC mains heated one.

> **Comments:**
> **username_0**: Hi, really thanks for your answer ❤️ I am not using a het bed as I am trying to make it as cheap as possible, and a het bed will also need a more powerful power supply which will increase the size. So, are you in short saying, a 2.5kg.cm motor is useable as it is the most reasonably priced and cheap motor from amazon  
> **username_3**: Hello Leo, For a small 3d printer that should be enough. The torque output on the stepper is directly proportional to the power that you put in, without it melting.  
> **username_0**: Thanks again ❤️ Would giving the power recommend by the seller be ok? I am really worried about the z-axis, will 2.5kg be ok? And also, is 20x20x20 really small for basic use? As, I used a rular to visualise the print volume, and it look small to me (Most likely because I haven't seen a 3D printer in real life as they are really expensive in my area) I am mostly only going to use it for electronics and robotics project that are not very big. Sorry for asking many repetitive questions, I was not able to find answers to these specific questions   
> **username_3**: You can exceed the voltage since the stepper driver will be proving the current via PWM, it should be fine. Better buy some spares just in case. If the motor gets too hot too quickly then turn down the power in the firmware's configuration.  

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