ZIPPER Noises

[david_gregas]

I just swapped the control board and drivers on my PRS Standard to sort out some issues I was having but now I hear zipper type noise when an axis starts and stops. Is what I am hear ramping noises.

David

[ed_lang]

I am hearing the same thing. That is if you and I are calling the same noise a zipper noise.

It started when I moved from the 1:1 motors to the 7.2:1 PRS motors.

I find it with M2,J2 and M3, J3 moves more then M1 or J1.

At first I thought it was the zzero plate sitting lose in the holder.

[ted]

Hi Guys,

Hard to know exactly what you mean by these noises. I imagine they might be different types of "zips" since Ed has been listening to his tool run for quite a while.

However, in general, there is certainly an acceleration and deceleration ramp at the end of each move. The faster you go (and the higher the resolution as in the shift from 1:1 to 7.2:1 gearboxes) the bigger the frequency change will be. So ramping is one possibility for something that sounds like a "zip". But note that the frequency would be a "down-zip" during the end of a move, that is, tapering off to a lower frequency as the tool stops.

The second possibility is that you are hearing the sound of the delivery of electrical pulses to the motors. The delivery is via PWM (pulse width modulation) process by which the motors are receiving power only portion of the time in the form of very high frequency pulses. The frequency is normally just above human hearing, but can sometimes be audible. Now, when the motors have stopped at the end of a move, they are also de-powered somewhat which may produce a slight change in the PWM sound that you are hearing. This is not a problem noise. You would hear the change just after the move has stopped.

Beyond that ?? Maybe we need a recording ...

Ted Hall, ShopBot Tools

[david_gregas]

I sort out my zipper noise problem by making some adjustments to my motor drivers. the geckos have a trim pot on them and there are instructions in the manual which can be downloaded at the Gecko site. I'm now issue free and very pleased with my machine and very, very pleased with the support I received from the people at ShopBot, thank you very much.

David