Belt length calculations correct?

I am ready to order belts for my build but am not sure my results are correct. I need HTD5 15mm wide belts. My calculations say I need a 464.7mm belt, does this sound right?

Drive Pulley: 15T Wheel Pulley: 66T Distance Apart: 5"

That sounds about right. There are 465mm belts available but I would take the next size, 475mm. Your motor pulley teeth engagement might be a bit low though and it will probably slip. Think about increasing center2center distance or using larger motor pulley or (perhaps the best) an idler pulley. All of which will affect the belt length so don’t go shopping just yet :slight_smile:

5" is as far as I can go in the extended mounts with still having a small bit of adjustment for tension. I can gonup to 16T but not any more as I’m a 250lb guy and don’t want to lose all the torque. Do you think I would still have slipping issues running dual 15mm belts?

Cannot be sure really, no one knows that. 15T to 66T is seriously steep so I suppose you will have 4 or 5 teeth engagement. If increasing c2c is not an option and also you don’t want to increase motor pulleys you can try it like this and always add idler pulley later. You will just have to get set of longer belts later. But belts are not that expensive anyhow :slight_smile:

Being i have zero knowledge of idler pulleys I will try it like this first and then research and add them if necessary

Use the belt length and center-to-center calculator from SDP-SI. It will even tell you teeth engagement

belt length and center-to-center calculator from SDP-SI