Pulley Design

A project log for A 2.5D Slew Ring

I need a slew ring for my SCARA. I don' have a 3D printer so it has to be either laser cut (2D) or 3 axis CNC milled (2.5D).

agp.cooperagp.cooper 05/16/2019 at 05:500 Comments

T5 Profile

I started with the T5 pulley and belt profile because I need a large tooth to suit CNC machining. But recently I found that the GT2 profile can be drilled with a 1.3 mm diameter bit. Sure the outside perimeter still need to be cut. So I will reconsider the pulley and belt profile later.

Here is the 12 tooth pulley and belt profile that I coded:

The belt is wrapped around the pulley (the red circle is the pitch circle).

Note how loose the fit is! This appears to be part of the design feature:

Other belt profiles (GT2) have lower backlash and should be considered later.

Here is T5 belt profile:

and the pulley profile:

And here is the design:

Here are the calculations:

Cog and Belt Design T5
Pitch 5.000 mm
Z1 12 t
Z2 60 t
Z1 Pitch Diameter 19.249 mm
Z2 Pitch Diameter 95.643 mm
Pitch Centre (meshed) 57.446 mm
Offset 17.868 mm
Cog Centres 75.314 mm
Belt Length 350.000 mm
Belt Teeth 70.0

Z1 Outside Diameter 18.249
Z2 Outside Diameter 94.643

I will upload the spreadsheet to the file area.