one inch does not measure one inch

Hello everyone,

This is my first build. 5x5 plasma/router table. (digital keiling drives,600,600,276oz motors,timing belt with belt reduction on x and y,pmdx-126 breakout,cable system to keep x axis square, steal frame, extruded aluminum gantry,miller plasma,skill router) Please don't make fun, I built it from scratch mostly piece by piece (very limited budget). I've got the software loaded and home switches set and changed the homing sequence to suit etc etc. In the config setup wizard I've set everything as it is; steps per revolution, micro step, pulley reduction, (which is different on every axis) and the machine is very repeatable but an inch does not measure an inch. I can just find the difference and scale my autocad drawings to compensate, but i would like to have it right. What is the best way to cheat the numbers to make my measurements accurate. Or what am i missing. Thank you very much for all the answers that I've already got from this board. And thanks to all the people that help with linuxcnc. Its awesome.

Kyle

we need information on what it does measure ! ,,, i.e when you move an inch how far does it actualy travel
details of belt reduction and pully size etc , your calculation of steps per rev , microstepping , to determine your steps per inch ( or mm etc )

well, on one axis my step per rev is 200, the micro step is 5, the reduction ratio is 14/78, my error was in the leadscrew turns per inch. my main drive pulley is 10 teeth with a 3/8 pitch so .2666 revs per inch. Some how I had .342 the first time. All is good now. Thanks for you help though. mach has a calibration feature and i guess i was kinda wondering if there is anything like that for linux. I don't care if there isn't, I am still very happy with linuxcnc so far.

use stepconfig

glad you got it sorted , so easy to miss punch the numbers in !