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I am making a gear/cog to attach to a high torque stepper motor.

I can realistically make it out of the following variety of materials:

  • 3D printer PLA/PLA+ etc.
  • layered PLA/PLA+ and fiberglass made with high strength epoxy
  • ply wood
  • ply wood with fiberglass coatings

The easiest cheapest gear for me to make with my tools is made with PLA, and perhaps I can sandwich some casting epoxy with fiber filings mixed in to increase the width + exterior surfaces coated with a layer of fiberglass.

But since this is going into the core of a thing I am making on top of a "high torque" (the Nema 23) stepper motor, I would want the structure of it to last at least a little while, and the teeth not to grind themselves to grit.

What is the ideal path forward? (Going for customizability, cheapness, ability for me to make, and ability to interface with more fragile cogs and components further out from the main driving gear without tearing them apart).

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    $\begingroup$ Why not purchase gears? There are numerous companies that service prototyping needs. Nothing you can print will match the performance and strength of a machined gear. $\endgroup$
    – Eric S
    Jul 24, 2021 at 20:12
  • $\begingroup$ torque = force×lever arm. If the gear is large enough, you'd mostly have to worry about the inner portion which should be pretty easy to reinforce with metal-collars or even just plates and bolts. If you truly need a custom shape and strength close to machined, pony up a bit for laser cut sheet metal. would put that CAD to good use and might even be cheaper than some quality metal ots gears $\endgroup$
    – Abel
    Jul 24, 2021 at 20:34

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What tools do you have available? 3D printed and layered PLA is your best choice if you only have a 3D printer.

For gears you usually want precision within .005" or less. You could CNC route material but I would not recommend wood (ply or lumber) as it would split easily when stressed along the grain. Fiberglass coating would help but then again you would need to very accurately control the layer thickness. If you were to CNC a part you may as well use a stronger base material.

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  • $\begingroup$ I only have a 3D printer, casting materials and epoxy right now. Some experience making fiberglass and a lot of CAD experience. I listed wood up there because I am willing to spend the money necessary to work with wood for this project, but I don't have the ability to work with metal. $\endgroup$
    – Chris
    Jun 24, 2021 at 19:53
  • $\begingroup$ But what you are saying is by the time I am working with wood, I'll have spent enough money to work with metal anyways via CNC? $\endgroup$
    – Chris
    Jun 24, 2021 at 20:01
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    $\begingroup$ If you're considering a one-off or otherwise small quantity production, there are online services providing CNC designed parts at a price lower than building your own CNC setup. I've not used sendcutsend yet, but I'm keeping it in my toolkit-of-the-mind for future projects. eMachineshop is another and there are probably more from which to choose. If you have a 3D printer, you can build and experiment at very low cost. Even if you destroy the part you've built, the loss in material cost is small, but the experience gained is great. $\endgroup$
    – fred_dot_u
    Jun 24, 2021 at 20:08
  • $\begingroup$ I wouldn't recommend CNC routed gears regardless, it's just a tool some higher end hobbyists have access to. What torque and size gear are you working with? A workaround to weak material is increasing the face width of the gear to have a larger area to distribute stress. Protolabs or other equivalent job shops can make metal parts at low cost and quick turnaround if you need to go that route. $\endgroup$
    – jko
    Jun 25, 2021 at 11:34
  • $\begingroup$ @jko I purchased a hobbyist level CNC with FreeCAM on Rhino3d. I used to be in a CAM pipeline as the rapid prototyper, but am new to the CAM part. $\endgroup$
    – Chris
    Jul 24, 2021 at 21:04

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