If your pitch is off .001" in 5", and you calibrate for a 5" part, you'll be off .02" on a 100" part.
If you calibrate the machine at 100", a 5" part will be off .001".
I'd prefer the latter.
If your pitch is off .001" in 5", and you calibrate for a 5" part, you'll be off .02" on a 100" part.
If you calibrate the machine at 100", a 5" part will be off .001".
I'd prefer the latter.
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Yes, but I am talking about calibrating 5" to 5.000" and NOT to 5.001". As I said, this assumes linear inaccuracies. If your screw is perfect at one end and off somewhere in the middle and so-so the other end then you have to chose what is important. Making 5" cuts and measure the cuts over the 100" table would tell would tell you if the screw is linear or not, and where it is the worst/best. If the pitch is off then that can be adjusted by the steps per value to get accurate cuts. That's what I did with my machine, after all, a 1605 is NOT 16.000mm in diameter with 5.000 mm pitch, but a little more or less, so taking some reference measures and adjusting the steps per values are necessary. This is common practice also with 3D printer, where the differences can be even more.