Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Tweakie.CNC on March 02, 2011, 10:51:48 AM
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If like me you use steppers then with this simple little device you could possibly double the reliable rapids (G0 moves) on your machine. Obviously it is not intended to offer any improvement to the G1 feedrates because steppers loose torque as speed increases and a reasonable torque is always required for cutting etc.
I recently spent an hour or so reading and re-reading this thread on the zone http://www.cnczone.com/forums/stepper_motors_drives/32284-my_take_stepper_damper-23.html and although convinced I just had to prove it to myself. Guess what, in the trial, it easily doubled the feed rate before my stepper stalled. This device has been patented so it’s only suitable for personal use but it is so easy to make you really just have to try it.
There is no point in going into the details of its operation here because it is fully described on the Zone - it perhaps looks similar to a flywheel but if it doesn’t rattle then it doesn’t work. Physics sometimes reveals itself in strange and mysterious ways.
Tweakie.
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If you watch my video in that thread, you'll see an amazing difference. My machine, with Xylotex drives, would be practically unusable without them.
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Hi Gerry,
I always wondered how you got your machine to go that fast - now I know ;D
Tweakie.
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Very interesting Tweakie.
Didn't read the entire thread, but did you see any mention of the Gecko drives that have resonance damping having the same effect ?
Negating the need for a mechanical dampener ?
Just curious as to how effective the Gecko is at damping and if it eliminates it as the graph in their doc. shows.
Thanks,
Russ
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Hi Russ,
I cant say that I noticed any comparison tests having been done between Gecko dampening and fitting a mechanical device.
Obviously some drivers are better than others at reducing the mid life crisis and as Gerry said Xylotex is pretty poor at it.
I don't have any Gecko's at present or else I would try a comparison. I have, however, found that with the same motor (without the damper fitted) a Toshiba chipped driver performs better than an Alegro chipped driver - backing up what Jeff Birt was saying in another thread. Fitting the damper there was little, in anything, to chose between the two.
Tweakie.
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Hi,
Is there any standard or the bigger the motor, the bigger the dampener
I have some resonance problem on my X axis with two 980oz stepper motor.
Always thought that this was cause by the screw(2 screws of 78in)
Maybe I could give it a try
Jeff
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Jeff,
I think what we are looking at here is an initially small but dynamic resonance within the stepper motor itself which results in the stepper motor stalling at a speed well below it’s maximum RPM capabilities. I don’t think anyone has worked out any formulae for calculating the mass of the damper or it’s distribution in fact I am not even convinced that anyone knows exactly how or why it works. It seems that all those dampers which have been constructed on the Zone are different or at least have a different mass distribution yet they all work. How can this be?
It would seem that the mass of a damper is not directly related to the stepper size but ‘trial and error’ is pretty much par for the course when designing one. I think you should give it a try and report back. ;)
Tweakie.
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There is electrical and mechanical resonance involved with all this. Mechanicaly, by adding the damper, one is providing a device to move the resonance point away from where resonance will occur. In analysis, you analyze based on some known base frequency and then additionaly at harmonics / modes out / up to 16 away or even more. The natural frequency of the system can be calculated manually, but a computer program is required as it get's complex quick. It becomes difficult to model the system as a number of assumptions need to made based on the system components and how they are made up. More later .....got to go ........
RICH