> The Allegro manual may shed more light on it: > http://www.allegromicro.com/en/Products/Part_Numbers/3977/3977.pdf > > I don't have a lot of experience with steppers, my mill was a working > system from the factory, so it "just works". I have been playing with a > small stepper and an L298 driver, and had some success but I haven't > come up with a tuning strategy. Your step/dir driver is more complex. It > is a micro stepping driver, so the number of sub-steps per normal step > is selectable. The decay setting seems to allow the drivers to behave > differently for different sub-steps. I haven't read through the > datasheet, but it didn't look too terribly obvious. > > This link seems to have some information: > http://www.piclist.com/techref/io/stepper/hipwrbp-gm.htm > > Bipolar steppers are driven by h-bridges. The H refers to the normal > schematic representation of this kind of circuit. The driver is an array > of four transistors or, more simply, switches. The direction of current > through a stepper coil is controlled by turning on the top right, top > left, bottom left and bottom right switches so that the current goes > forward or in reverse. There are two coils, so there are two h-bridges > to control one motor. > http://en.wikipedia.org/wiki/H-bridge > > With the details being pretty complex, it may be best if someone with > experience chimes in with a rule of thumb on how to select a proper > decay setting. It may be that the setting will only make a few percent > difference. From what little I've read, it may affect the noise and > efficiency at certain step rates, or help slightly with slipping at > intermediate step rates, but this is a guess. If this is the case, it > may be that just trying different settings and keeping the ones that > help may be the way to go. > > What is the voltage of the motor power supply? The datasheet says the > driver is rated for 37 Volts, so it would be nice to have the supply > voltage close to that. The power supply should have a large capacitor, > or a pair of them. They shouldn't bulge a all, If they do, they may be > on their way out.
Hi Kirk: Just a note to tell u that I took ur suggestion and ordered ball screws for my mill. That means that I have to make a few more castings and do a lot of machining. I downloaded the info from Allegro. That provided a lot of info and I now understand what I'm trying to do. Thanks for the info! While working my way through the redesign, I will use the steppers I have and see how much the new screws help. To answer ur question, the power supply is 32 volts @ 6 amps. The caps. are new 1000 uf. @ 50 volts, I used two of them. That is what the manual I got with the controller called for. It also talks about heat sinks and a fan to cool the chips. I included the fan at time of the install of the stepper board. I will now install the heat sinks also. I am going to have to use reduction, ( 4 to 1 ), to drive the screws as they are 4 tpi. So I will change the micro step back to 1/2 step. That should give me more torque. Will include a photo later. Bill ------------------------------------------------------------------------------ Protect Your Site and Customers from Malware Attacks Learn about various malware tactics and how to avoid them. Understand malware threats, the impact they can have on your business, and how you can protect your company and customers by using code signing. http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
