# Setting Up Merlin Still using Sprinter

Posted by Justinjjhcs1
 Setting Up Merlin Still using Sprinter May 21, 2015 05:40PM Registered: 11 years ago Posts: 51
Ok Calibration for Merlin is compleatly different from Sprinter, I thought I could just Copy the Steps and Endstops. I cannot get Merlin to work for me as reliably as Sprinter.the Steps and every part of the Calculations are Totaly Different.
Sprinter
#define _AXIS_STEP_PER_UNIT {83, 83, 3200/1.25, 400}

Merlin
#define DEFAULT_AXIS_STEPS_PER_UNIT {78.7402,78.7402,200.0*8/3,760*1.1}
Yeah I know X=78.7402 Y=78.7402 Z=200.0*8/3 E=760*1.1
But what base did they use to get that Calibration I am assuming (E) is one compleat turn is 180Degrees times 1.1 full step divided by What 3.14 radious squred??
How did they come up with that figure and still have ot work?
 Re: Setting Up Merlin Still using Sprinter May 22, 2015 09:17AM Registered: 10 years ago Posts: 869
The formula I like best come's from Nophead's build manual for the Mendel90. The forumla is:

E_STEPS_PER_MM = ((# Steps per revolution * # teeth large gear)/(# teeth small gear * effective hobbed bolt diameter * pi))

For example, if I had a standard 200 step motor running at 1/16th microstepping, that's 3200 steps per revolution. A common Wade's gear extruder ratio is 39:11. A 8mm hobbed bolt has an effective diameter of around 6.75. Plugging in numbers, we get:
(3200 * 39) / (11 * 6.75 * 3.14159) = 535.289