Hello.
As it turned out in this topic i got the broken Spindle Speed Controller.
Therefore ripened a question: can i connect the Quiet cut spindle without a speed controller? Directly to 24V or 48V power supply? Is it save?
I have got the quiet cut spindle 48V. And i’ve already tried to connect it to 24V power supply for short time. Spindle works well. But now i want to carve few holes in wood piece. It’s 18mm of pinus sylvestris.
Thank you.
You can connect the spindle directly to the 24/48 volt power supply without damaging the spindle. It will run at full speed with 48 volts. You would have to adjust your depth of cut and feed rate to match up with the spindle speed and the characteristics of the material that you are cutting.
Hm, guys from inventables recommend to don’t do it.
Did they say why? It’s no different than running the speed controller with the potentiometer turned fully on, or using the speed controller with a speed setting of S12000 or above using the PWM control from grbl.
They have not led weighty arguments 
Only that i can’t control the speed. I think they can’t advice to do something that didn’t arranged in their articles, just for save himself.
It should not be a problem if you are careful to make sure the spindle starts and watch your chip load.
Starting the spindle at full speed requires a high amount of current and your current is related to your chip load (to a point). High current demands (at start up or with a higher chip load) could put the power supply into current protection mode (the power supply will turn off and stay off until it is reset by being unplugged for about a minute). The speed controller limits this current (starts the spindle slowly and prevents the power supply demands from getting too high) so the power supply dosen’t need to provide the higher current and will no go into protection mode.
Assuming your power supply can survive the back emf and you are aware of the issues you should be fine. Watch to make sure it is not getting too hot just in case.
