First off, Hi! I'm new to this forum and new to CNC. I'm not even sure I'm posting in the right section. I'll get right down to it. I bought a home built CNC with a cutting area of 2' x 4'. I wish I'd done more research because I wouldn't have bought this one after all I've been through with it and what machines I found afterwards. After setting it all up and running test after test, I have what I would consider major accuracy problems on the X and Y axis. It's a rack and pinion setup. X axis has a 3:1 pulley with a YA20 boston spur gear. Y axis has 3:1 and a YA15 gear. Stepper driver is a Gecko G540 and 1.8 degree stepper motors. I guess my question and fear is, what amount of accuracy should I be getting with this machine? With the current settings in EMC2 (set to everything it's "supposed" to be according to everything I've read). It is only really accurate at long distances of 36". The less I go the less accurate. For example, I set it to cut 3.5" on the Y and it cut 3.6". I have Onsrud bis and a precise bits collet. I would just make adjustments to the measurements if I could, but since the accuracy changes over the coarse of length then it seems impossible. So is this what I should expect or am I doing something wrong? The Z axis has a 16 TPI lead screw and has no issues. Any help would be much appreciated.