[project5k]

ok, let me see if i get this right... you have a 13t on the motor, and a 40t on the jackshaft, then also on this same jackshaft there is another 13t that actually moves the chain that is tied to the gantry and moves it... yes??
the you do not have 1:1 you have 3.076:1 meaning that your motor will turn a little over 3 times for each rotation of the jackshaft... so then you take your motor rpm, lets just say 600 rpm for round math... so then the motor is spinning at 600, devide that by the 3 we got for reduction, and that means that the jackshaft is spinning 200 rpm... then to figure the travel rate, you would multiply the circumfrence of the other 13t on the jackshaft by the 200 rpm, so just as an example, if the circumfrence is 5 inches, then your traveling at 1000 inches per min.... also, if your motors are 1.8 deg, and with this gearing, you would take the 200 steps per rev, times your reduction, so thats 200*3=600 steps per rev of the jackshaft, and then devide that by the circumfrence of the 13t on the shaft and thats 120 steps per inch travel... does any of this make sence, or did i totally miss the question...