Rob, Thanks for the recommendations! You're exactly right, there's LOTS of documentation - it's a little daunting to wade through at times. Not to mention the time required.
I tried inverting the direction signals and it didn't make any difference.. HOWEVER.. I had not run the stepconf utility since upgrading to 2.3. I found that with this version I could was able to play with the steplen and stepsize variables and drop them significantly and still remain stable - and things are now much faster (max stable velocity before was 9in/ min now it's around 25in/min if I let it go full out). I'm not sure how things are now different, but we'll see. I wish I had more detailed information on the requirements for these steppers. Maybe I'll just upgrade them to something known and be done with it. I'm not SURE about the Z axis variations, but things seem to be more stable - I'm doing an engraving right now, so the jury's still out, but it looks good. On May 7, 2009, at 12:28 AM, Rob Jansen wrote: > Michael, > > the documentation is of course the first thing where to look for the > information you need. > But having been there myself I know it can be quite overwhelming ... > >> I've been reading in parts of the documentation and troubleshooting >> pages that some of these issues could be due to step length and such >> being set up incorrectly. >> > In you previous posts, beginning of April, you already mentioned that > you changed the stepper timings and inverted the step signal. Step > timings of 2,000 us (is that 1,000 for the step len + 1,000 for the > step > size or 2,000 + 2,000) are not that fast. Usable for most drivers and > motors (I've got big (slow) ones driven at that (2,000 + 2,000) rate > without losing any steps). As I found out inversion of the step (and > dir!) signals may make the difference. Most stepper drivers use opto > couplers connected between the I/O bit of the parallel port and the > +5V > supply (I took that from a USB port on the PC). As long as the stepper > motors are not moving, the step signal is low and it is only being > pulsed high if a step signal is needed - this means that there is a > current flow through the LED in the optocoupler when the motors are > idle. Having a (fairly high) current driving the opto couplers all the > time may just be too much for the port. On my FPGA board I had to > invert > both the step and the dir signal - the dir signal only becomes active > when driving the step signal. >> Do these numbers look normal? The MAX_VELOCITY and MAX_ACCELERATION >> look strange to me.. but then I don't know what normal is.. >> > these values are in (inch?) per second and inch per second squared. > MAX_VEL = 0.1 means 6 inch per minute - seems a bit on the slow side > for > my machine (I have 25 mm/s = 59 "/min). With these values you should > at > least never hit >> The backlash is a little high - it's on the list.. but otherwise what >> should I be looking for here as "normal". >> > Backlash is what you would have to turn the handwheel before the mill > starts moving. 0.008 inch (0.2 mm) looks OK - that is normal on my > hand > operated mill. >> 2) I seem to be having some issues with my Z axis loosing steps (X >> and >> Y seem to be pretty stable). When making a series of up and down >> moves for some engraving, the depth gets reduced as the program >> progresses. >> > That is funny. Most of the times when loosing steps this is due to > combined speed and load which would mean that loosing steps in the Z > axis would mostly result in deeper engraving. But (see remark on the > top > of this mail) inverting the dir signal may do the trick. >> 3) Is the step generation dependent on the stepper motor driver, or >> the stepper motor itself? >> > Both. The driver has maximum values specified, this mostly limits your > step size and step len signals (and the max. stepper frequency) but > the > motor is mostly slower than this so the max accel and max vel are > really > determined by the motors. >> Any advice or pointers to any good resources would be greatly >> appreciated. Remember.. I'm a NOOB at this, detailed explanations >> would be GREATLY appreciated. > The docs - I discovered that a lot of questions that I had would have > been answered by reading the docs. Only problem I had was that there > was > so much documentation and so little time to read ... > > Good luck, > > Rob > > > ------------------------------------------------------------------------------ > The NEW KODAK i700 Series Scanners deliver under ANY circumstances! > Your > production scanning environment may not be a perfect world - but > thanks to > Kodak, there's a perfect scanner to get the job done! 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