CNC mill belt

David G · Feb 12, 2017

I am looking at using a 2:1 reducing cog belt on the Z axis.

My width choices are 10mm, 15mm or 20mm, max torque is 6.25 ft lb at the motor.

What do you think for belt width?

David G · Feb 12, 2017

Sorry, 3:1 reduction

JF in MI · Feb 12, 2017

I seem to remember around 10 mm on the machines my company built and that would handle a considerable amount. Most of the component manufacturers I dealt with had pretty comprehensive data sheets IIRC.

David G · Feb 12, 2017

Thanks, got one coming.

Indiana Ken · Feb 12, 2017

(quoted from post at 17:05:35 02/12/17) I am looking at using a 2:1 reducing cog belt on the Z axis.

My width choices are 10mm, 15mm or 20mm, max torque is 6.25 ft lb at the motor.

What do you think for belt width?

The belt tension is a function of the pulley diameter on the motor. For example: A 2.0" diameter motor pulley would have a radius of 1.0". Belt tension = (6.25 ft-lb x 12 in/ft) / 1.0 in = 75 lbs. A smaller motor pulley would result in a higher belt tension at max motor torque. There should be specs in the belt catalog.

David G · Feb 12, 2017

Sounds like they are snug, like timing belt on car.

Steve@Advance · Feb 12, 2017

At that low torque and speed, I would go with the smaller belt. The smaller the belt, the less motor torque will be wasted turning, the less inertia for starting, stopping, reversing. But another consideration is the availability of components. Be sure everything you will need is available off the shelf to avoid special order delays and extra costs.

One thing I would try to do is go with the largest motor pulley you can work into the design, for the purpose of keeping the most teeth in mesh as possible. This will reduce backlash, make the belt last longer, and reduce wasting motor torque bending the belt around the sprocket.

Janicholson · Feb 12, 2017

The Z axis needs to continually lift the spindle and drive mechanisms associated. Our HAAS uses 15% loadin the Z+ direction most of the time. The motor must "fight" this at all times, so higher numeric ratio helps. Jim

JF in MI · Feb 13, 2017

Forgot to mention; there are 2 types of cog belt drive systems (pulley design mostly if I remember). I forget the names but one is a drive belt for going only in one direction and the other drive type is for reversing direction. The reversing type has far less chance of losing position due to no play/backlash.

CNC mill belt

David G

Well-known Member

David G

Well-known Member

JF in MI

Well-known Member

David G

Well-known Member

Indiana Ken

Well-known Member

David G

Well-known Member

Steve@Advance

Well-known Member

Janicholson

Well-known Member

JF in MI

Well-known Member

Similar threads