NEMA23 pully and pinion

[RonVais]

Hey guys i want to move my stepper motors (3Nm NEMA23 Motors) so they will not stick out so much
like here on the Z axis:

30249

so i opened aliexpress and the amount of options of pullies and timing belts was overwhelming
how do you choose the timing belt and the pully?

Thanks!

[dazp1976]

Hey guys i want to move my stepper motors (3Nm NEMA23 Motors) so they will not stick out so much
like here on the Z axis:

30249

so i opened aliexpress and the amount of options of pullies and timing belts was overwhelming
how do you choose the timing belt and the pully?

Thanks!

1. How big do you want the pulley diameter to be (space limitations or weight).
2. What ratio do you want to have.

[JAZZCNC]

how do you choose the timing belt and the pully?

First, you decide on the width, this will depend on the application but I prefer 15mm width as they handle the loads better and stretch less than 9mm.

Then you choose the profile type, HTD is the better choice for CNC as it's low backlash.

Next, you choose the number of teeth of each pulley. ideally, you want the smallest lightest pulley possible to help with the interia, however, you need a minimum number of teeth engaged at all times, usually around 5 teeth but does depend on pulley size. I find 18 or 20 teeth to work best. If you go much smaller than this it gets difficult with the size of boss and fastening. Again, it depends on stepper shaft size, etc.

Belt length is simply a calculation of the centre distance and pulley size, there are many belt length calculators on the net to help with this.

My go-to belt setup is 15mm HTD with 20 teeth at a 1:1 ratio.

[RonVais]

so lets say this one is ok? (20mm width)
https://www.aliexpress.com/item/4001165841111.html?spm=a2g0o.productlist.0.0.31545 860lHqOnA&ad_pvid=202107160733335096300742931000005279708_2&s=p

with this timing belt?
https://www.aliexpress.com/item/4000364193602.html?spm=a2g0o.detail.1000060.3.1e5e 5346p0wCCp&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=3e01b565-52e8-465a-b340-d7a3a3d8c1fd&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:3e01b565-52e8-465a-b340-d7a3a3d8c1fd,tpp_buckets:668%230%23131923%2368_668 %230%23131923%2368_668%23888%233325%2314_668%23888 %233325%2314_668%232846%238108%231977_668%235811%2 327179%2337_668%236421%2330821%2312_668%232717%237 561%23367_668%231000022185%231000066058%230_668%23 3468%2315607%2329_668%232846%238108%231977_668%235 811%2327179%2337_668%236421%2330821%2312_668%23271 7%237561%23367_668%233164%239976%23304_668%233468% 2315607%2329&&pdp_ext_f=%257B%2522scene%2522%253A%25223339%2522% 257D