Does anyone know the belt pulley type and pitch for the stock K40?

Does anyone know the belt pulley type and pitch for the stock K40? Seeing some conflicting info out there, including a belt from Lightobject listed as 2mm pitch, but I doubt it’s exactly 2mm as they have a 2.3mm pulley listed for the k40.

Both belt and pulley are 2.3mm pitch

It’s a chinese copy of MXL pulley 0.08” pitch (2.032mm)

The lightobject k40 belt is the correct version but they have the pitch misprinted in the description.

It is not 2mm GT

ok, thanks. Good info to know. Next time I go by LightObject I’ll let them know there’s incorrect details on their description.

Hi. Is there a way to upgrade to a standard belt and pullys?

To be clear, MXL isn’t non-standard. As @Jim_Fong was alluding to, it’s just an imperial standard belt pitch (2.032 mm = 0.08 inch), and the K40 is set up for 1000 steps per inch. If you want to run in metric, I would expect you could switch to GT2 belt and pulleys; you’ll just have to do some scaling if you want to do that while still using the m2nano board.

Be aware that there’s lot of junk sold for 3D printing, and cheap GT2 pulleys are often not bored perfectly concentric, which can cause some fairly subtle artifacts. If you, say, print a scale, the overall length will be right, but it will be locally compressed and expanded slightly on a pitch corresponding to the circumference of the pulley. So for a 20-tooth 2mm GT2 pulley, you would see a 40mm repeating pattern of slight expansion/compression.

Basically, I wouldn’t make that change without knowing and accepting the tradeoffs.

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It actually works out to 2.032=0.08" and that corresponds to 157.5 steps/mm or 400 steps/inch for stock k40 motors and pulleys. I’d just find mxl belts and pulleys and replace with the same parts.


I updated the Belts section in our replacement parts resource to make this clearer:

Please feel free to add more sources for MXL 0.08" inch belt to that article.

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Thank you for the info on the K40 difference. I wondered why people did not just change over.

I am aware that I know just enough to be very dangerous to my self and any one close.

Thanks. John

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@Tatarize posted some great videos explaining how the K40 works, related to his work on #k40:meerk40t to drive the K40. Definitely worth watching. Check out his youtube channel

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