In this video I’ll show you how to model straight GT2-6 timing belt and how to model continuous belt around two pulleys in a plane.

## The centre to centre distance

When modelling a belt around two pulleys we have a few constraints:

• the pitch circumference of each pulley
• the pitch of the timing belt

What we need is the ideal distance between the centre of the two pulleys so that the belt fits perfectly. The centre to centre distance is described as

$C = \frac{b+\sqrt{b^{2}-32(D-d)^{2}}}{16}$

• C = center to center distance
• D = diameter of pitch circle of gear 1
• d = diameter of pitch circle of gear 2
• b = $4L - 6.28(D+d)$
• L = pitch of timing belt

For Fusion 360 you may find that it is easier to break the large equation into smaller sections like calculating ‘b’ first.

## Final thoughts

Should I do a follow up with other kinds of belt? Other designs? Let me know.