Just typed "stepper resonance" into Youtube and came up with this. Interesting that they have an almost identical machine to mine (looks like the Amadeal version) and to quote "I was so FED UP of stepper motor resonance". So he fitted Servo motors instead. Seems a bit OTT though.
Birchy if you do end up buying new drives then the AM882 is the drive if your having Resonance problems because you can adjust the Resonance range the drive covers with Pro tune. Your Analogue drives are stuck to set range which is narrow and if indeed it is resonance then your drives Resonance algorithms are not looking in that range or even working at all.?
The Dampers you see are usually only affective on cheap drives that don't have any resonance handling capability and I'm sure the M542 does have some basic capability and although it may only be basic it's better than none.?
Regards Micro stepping then above 2000 is generally pointless has the motors can't resolve much more than that and your only stressing the machine and increasing chance of dropped pulses/steps etc.
Higher MS does help with smoother motors and I generally prefer 2000 if the PC/Parallel port can handle it but anywhere above 800 generally works ok.
So now I'm more edumacated on steppers and drives, it's obvious that there will be resonance somewhere in the speed range unless using tunable digital drives. At 3x the cost of an analogue drive, I'm not so convinced that the digitals are worth the extra cost at the moment. No doubt they will become more reasonably priced when more people adopt them.
Since my last post, I have refitted the Y-axis motor and pulleys, belts and X table (with a 25Kg lump on top) so that I'm testing the motor under normal conditions. I then created a g-code file to test all feed rates from 0 to maximum velocity, increasing in 5% steps. This helped me isolate the speeds/frequencies at which resonance was most noticeable. Starting at 2 microsteps (1/2 stepping), I ran the test file for each setting up to 64 microsteps. The resonance band was tightest and least noticeable at 8 microsteps, so that appears to be the optimal setting for my machine. I also gave the machine a good hammering with randomly generated G0 codes (thanks Jonathon) at full speed and acceleration of 2000. The machine danced around a little due to the high inertia changes but the main thing is that it didn't lose any positional steps. I've now put the acceleration to a more sensible 250 to prolong machine life.
Now I need to stop farting about and get on with finishing the Y-axis before contemplating the X and Z...
Back in the early days when we were having loads and loads of problems with Gecko 210 drivers there was a problem using 10 microsteps.
Marris explained it at the time and it made sense but can't remember what it was.
When we moved onto the Chinese drives we chose 8 microsteps as the defacto default and have stuck with this over the years.
Nice to see some tests proove what we discovered then.John S -
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