I need help for 4th axis Build

[Rene Nuñez Paz]

Hi, Iam building a 4th axis for my CNC router
Iam thinking in use two different pulleys an a tooth belt

Is a lot of info in web, but Iam not sure if is right for me.

My Steppers are Nema 23 1/4" shatf 305Oz/In

Iam Looking in SDI-SP.com but 1/4' shaft in my steppers
limit the search.

Finally I select the bigger pulleys pitch and belt with
as possible.
My selection is

Pitch 0.2inches (5mm)
Belt with 0.375 inches (8.9mm)
Reduction 1:4 using

Pulley 1
15 Teeth 1/4" bore

Pulley 2
60 Teeth 1/2" bore


Is 0.2" pitch addecuate for this kind of work?

I tried to select 0.375pitch but any small pulley
had 0.25 inch bore for my steppers

Do you think that this selection is enough
for turning/milling soft wood of 150-200mm diameter
and 1000 mm max lenght?

Can you sugest me other economical pulleys and belt suppliers?

Whats the best practical belt material?

Thanks in advance

Rene
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[ger21]

I think you need to use two belts to get a higher reduction, closer to 8:1 or more. At 4:1 you probably won't have enough holding power.

[Rene Nuñez Paz]

Hi , Thanks for your response.
But Is a god selecction use a 0.2" pitch pulleys or I shuld use a bigger pitch.?

I saw some 4th axis in web using small steppers, but I don't have idea
about how can do job using small steppers.
Thanks

Rene