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I am make a DIY 3D printer. And I need to which stepper motor I should use. So, I am planning on making a 18x18x18 or 20x20x20 max print size. I am only having a single z-axis like the prusa mini. Which stepper motor should I use for my z-axis, x-axis, Y-axis and the extruder (Planning on using 1.75 mm filament). How do I calculate the power needed? Will 2.8kg or something near be enough? I am not really good at stepper motors, so sorry for the lack of knowledge.

I am not sure if I am following the rules by asking this question. Sorry

Thanks for reading

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  • $\begingroup$ 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. $\endgroup$ – Fernando Baltazar Jan 6 at 20:14
  • $\begingroup$ 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 ☺️ $\endgroup$ – Leo Red Jan 7 at 3:16
  • $\begingroup$ 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: github.com/prusa3d/Original-Prusa-MINI/blob/master/… $\endgroup$ – Leo Red Jan 8 at 11:02
  • $\begingroup$ 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. $\endgroup$ – Fernando Baltazar Jan 8 at 19:01
  • $\begingroup$ Oh, Thanks ❤️ I didn't think I can use a 2.5kg one for the extruder. It is going reduce the price alot! Thanks $\endgroup$ – Leo Red Jan 9 at 4:17
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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.

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  • $\begingroup$ 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 $\endgroup$ – Leo Red Jan 8 at 14:55
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    $\begingroup$ 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. $\endgroup$ – user77232 Jan 8 at 17:18
  • $\begingroup$ 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 😐 $\endgroup$ – Leo Red Jan 9 at 4:21
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    $\begingroup$ 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. $\endgroup$ – user77232 Jan 10 at 8:52

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