Encoder Diameter Disk Calculation

How do i calcilate the diameter of the disk to be used to install a encoder ? Is there a formula to calculate the diameter of the disk ?

Lets suppouse that i would like to get 5000 pulse/m and i have a encoder that have 2500 PPR ( pulses per revolution ) so i would like to know the diameter of the disk that must be used to get 5000 pulse/m using this encoder.

I would like to know too if this is the right way to work with encoder diameter disk?

thanks,
Luciano

I assume that by a 'disc' that you are referring to some sort of measuring wheel that will be mechanically attached somehow to perform linear measurement.

You want 5000 pulses/meter

You want to use a 2500 pulse/rev encoder.

(2500 pulse/rev) / (5000 pulse/meter) = 0.5 meter/rev

This is your desired circumference. Solve for diameter

Required diameter = circumference/ Pi = 0.5m / 3.14159 = 159.155mm

It's really better to work it in the reverse order. I mean, look at what you already have, or can tolerate, mechanically, then choose an encoder resolution that will get you close to what you want in overall resolution.

I agree John. I usually look at how much resolution I need for my application (pulses/mm or pulses/inch, etc) and then choose a feedback transducer and measuring wheel that will give me my desired resolution. Typically I will try and use a commercially available transducer and then size the measuring wheel as the last issue.

I try to pick a wheel & transducer combination that doesn't result in excess speed since this can result in early bearing failure of the encoder, and there is a greater chance of 'slippage' if a smaller wheel is used.