Machine runs far too slow (or fast) and the wrong distances - Confusing inch/mm 's

[Hugo Carradini]

Gerald I just finish connecting the rest of the cables. I went to the axis setting and told in setting axis to run 10 mm . It run 250 mm so I told the machine it run 250mm and the machine made the adjustment . Then I told again for checking to run 1000 mm and run 1000 mm exactly. The same with the other axis. The problem is that it runs to slow . When I jog it moves nicely but running a program in the air goes very slow. The other problem is that wen I jog the X axis and I stop it stops quickly , but axis Y wont stop the same, will run about 250 mm extra before it stops.
I was looking for setting the motors but the forum has grown so much that I cant find the formulas I remember seen before. I set the machine parameters in mm .
I have not got home yet so I will send the Igus information tomorrow.

[Gerald D]

Hugo, you have a machine with racks & pinions from an inch system, but you want to operate in mm. I also see you have 28 tooth pinions with 7.2:1 gearboxes. Your steps per millimeter must be set at 128.899

I changed the spreadsheet in this post (http://www.mechmate.com/forums/showthread.php?p=4089&postcount=27) especially for you - and anybody else whose rack & pinion inch/mm is different to the units that they want to run the machine in. In Mach the setting is Config > Select Native Units. Hugo, there you will select "MM's" and on Config > Motor Tuning you must type the value 128.899 into the block "Steps per".

[Hugo Carradini]

:oThanks.