Mixed Servo and Stepper system

Hi All,
Is there any reason why I could not have a mixed stepper / servo system? I may have to add a stepper driven axis to a servo driven 5 axis machine.

no reason at all , many people do just that for situations such as adding a rotary table .

which axis are you looking at adding , perhaps details of your problem , may throw some questions

I have a machine that has the x axis as the material. Meaning that we pull the material up and down with rollers. The material could be 13m long beams that could weigh more than a ton each. We discovered that the movement is not always predictable due to variances in the material. The PID tuning also keeps changing with every job as the the material could vary from 20kg to a ton or more. Not a good situation to try and do good PID control. The solution is to add a trolley to the x axis that will be driven by a stepper on a rack and pinion and that will now move the material through the machine under control.
I am looking at a 30nm stepper possibly.

yea you should be ok to go , although i'd perhaps look at using 2 steppers one each side ( without knowing or seeing the offending machine of course )

Dave

Thanks for the advise Dave. The nature of the machine is such that we cannot get into the area where the operations happen. That is about 2m wide cage that contains the z axis head (600kg worth) and the Y axis. There are two roller conveyors of 14m each on both sides. The closer rollers are powered and I use them to bring the material into range. That will change now. The trolley will have an arm to push the material into the machine. We will most likely use an electro-magnet to hold or connect to the material

yes i'd agree .. i'd use magnets