[Memran]

Hello,

I have some strange behaviour occurring on my mill, which I believe to be related to it being in an unheated, drafty, damp garage.

When I switch the controller to forward, the spindle starts as full speed immediately, even though the speed knob is still in the zero position. I can turn the speed knob to any position from zero to maximum, and there is no effect to the actual spindle speed.

After a minute or two of running, I hear a drop in the speed of the spindle. This led me to try leaving it running for a while to see what happens. Gradually, the speed reduced, and the ability to control the speed with the knob increased! Once it had been running for about 40 minutes, the controller appeared to be working 100% normal!!!

Now, I am also getting very similar behaviour in my stepper drivers. When I first turn it on and make some movements, each axes has an awful grinding sound, as if there is sand on the leadscrews, but is probably lots of missed steps. However, just like with the spindle, after taking some time to move an axis back and forth, it gradually smooths out and returns to normal function!

I took my control box and my 4th axis indoors to try to diagnose the problem (and failed), but the next day, I tried again, and it all worked 100%. After putting the control and axis back into the garage, it still worked fine, but the next day it was back to grinding noises.

Could this issue be due to the environment? My theory is that there could be a very small amount of condensation on the electronics, which evaporates with use.

Something I don't understand is, I've had this CNC'd mill for a few years, but it has only recently exhibited this behaviour.

I'm not sure what I can do about this, so any help would be greatly appreciated!

[Memran]

Ok it turns out that the controller is always at max speed, both indoors and out.

I am already on my 2nd control board, because the first one quit working altogether a couple of years ago, and so I am loath to buy another identical one.

Can someone suggest an alternative, preferably in UK?

Thanks!