View Full Version : Need advice w/ encoder selection

03-11-2006, 09:36 PM
I'm building a router table and need some assistance selecting appropriate encoders for use with Mach3. My concern is the max rapid movement of the axes.

I'm putting this table together from used parts acquired on ebay and elsewhere. The x and y axes are about 48" each in length. They're Bosch-Rexroth extruded linear guides w/ timing belts. http://www13.boschrexroth-us.com/Framing_Shop/pdf/113/Page%2014-12.pdf .

Each axis has a Bayside 100:1 gearhead (because they were mounted to the axes when I bought them). To these gearheads I want to mount some servo motors and turn them at 3000 rpm (no load). One full revolution of the belt drive sprocket moves the carriage (axis) about six inches. So 3000 rpm geared at 100:1 should give me about 180 inches per minute of movement on the axis. (I like that number...)

Here is where I get lost.

I have not purchased encoders yet, but will be buying US Digitals. I don't understand the relationship between the encoder cpr rate, the driver multipliers (electronic gearing), and Mach's step pulse rate.

I have a relatively fast computer so I assume I will be running Mach3 at either 35000 or 45000 step pulses per second. I will probably use Gecko 320 drives (or possibly Rutex 2010 drives).

Can someone here more knowledgeable than me recommend the appropriate encoder resolution to achieve the highest possible rapid movement, and give me a quick rationale for the recommendation? All input welcome!