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Anyone having a problem with "mid range resonance" when using Xylotex steppers at about 420 revolutions per minute? 420 revolutions per minute is roughly 21 inches per minute with a 20 threads per inch screw.
Here is my dilema... my TAIG mills X axis moves great at any speed from 1 to 45 IPM, the Y easily stalls but this is can be fixed by tighting the gibbs I just have not done this yet and the Z spindle assembly stalls but only when lowering and its always at 21 inches per minute. Gibb tighting for the Z is not an option I very much need for the spindle assembly to "hang" on the screw as I do not want the striction from a "tight" gibb to hold the assembly in place so that when the machine is cutting and the striction suddenly "lets loose" I end up with borked parts and chipped tools from the Z-axis backlash rearing its ugly head.
Any chance there is a quick way to kill "mid band resonance" without resorting to tighting gibbs? One thing suggested to me by Mr. Xylotex was a contraption that looks every bit like a... well here take a look yourself
Maybe something as simple as a round disc cut with an off center hole could do the trick just as well. The reason it would be offcenter is to create extra load on the motor in proportion to how fast it is spinning. I am told its the "load" that will stop the resonance and the lack of a load when lowering the spindle assembly that allows the resonance occur.
Anyone have a simple electronic approach to fixing this? I would much rather keep what I have and fix it but if there is nothing that I think is good enough and simple enough to do I will have to either try a step motor driver with "mid band resonance dampening" or a servo system.
Personally I liked the steppers so much good is said about them and they do not cost as much as servos but the resonance problem is really killing it for me.
Did you try making/using an anti-backlash nut? This might kill 2 birds with one stone. The friction on the nut will increase the damping on the motor.
are you using 1/8th step mode?
Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
Vist my websites - http://pminmo.com & http://millpcbs.com
If you are using a double shaft stepper, Oriental motor sells a damper you can mount on the back shaft that may help. A bit pricey at $42, though.
Mach3 2010 Screenset
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
In another post I commented about how I "fixed" .011 backlash on the Z-Axis and when I did that I made it so the Z-Axis screw does not spin as freely as before. Its not hard to turn but its definitely not loose like it was before and the mid-band resonance no longer occurs or at least its not noticable to me and does not cause the stepper to stall.
here is a link to my post about fixing TAIG z-axis backlash...
A fix for z-axis backlash on TAIG mills
Last edited by Smertrios; 04-10-2006 at 07:07 AM.