Franco did a easy to follow video series about the KBSI about a year ago on his PM mill. I recommend watching them if you have not seen them yet.
Re: Displayed Spindle Speed is Incorrect
Posted: Sun Nov 28, 2021 11:00 am
by Dave_C
Greg, thanks for posting that video!
Franco did not show how to hook up the two wires from the KBSI to the replace the 3 wires on the knob control!
Does anyone know what terminals on the KBSI hook to what wires on the three wire knob control?
I looked at the attached wiring diagram some post back but the colors are hard to read.
I'd like to know in case I ever need to do one of these, please.
Dave C.
Re: Displayed Spindle Speed is Incorrect
Posted: Sun Nov 28, 2021 1:40 pm
by Greg
On video #5 he shows the wiring.
Re: Displayed Spindle Speed is Incorrect
Posted: Sun Nov 28, 2021 2:46 pm
by francoCNC
Hi. I'm not an electrical engineer and I can relate to the challenges the "every man" has when trying to do spindle control on these DIY mills. When you boil it all down, you are replacing the manual potentiometer with a "digital" version. Manual potentiometers have three terminals (Ground, Output and VCC). You feed the max voltage to VCC and the Output voltage will vary depending on where you turn the knob. You measure the Output voltage between the Output and Ground terminals.
Pretty much all manual benchtop mills have a three terminal potentiometer and if you figure out the max voltage (measured between GND and VCC) you can adjust the signal isolation board to match. The voltage measured between VCC and GND typically represents the MAX RPM of the spindle. As you lower the voltage, the spindle turns slower.
The output from the Signal Isolation board will replace the Output and GND terminals of the potentiometer. The VCC terminal is not needed and serves no purpose any more.
Long story short: The signal isolation board replaces the GND and Output of the potentiometer. It also prevents your Acorn board from getting destroyed.
Re: Displayed Spindle Speed is Incorrect
Posted: Sun Nov 28, 2021 6:48 pm
by Dave_C
Most excellent video! Even I can do one of these now, LOL
That answered all of my questions and hopefully the OP will be able to solve his as well.
On to the next probelm!
Dave C.
Re: Displayed Spindle Speed is Incorrect
Posted: Mon Nov 29, 2021 7:54 pm
by WVDualsport
francoCNC wrote: ↑Sun Nov 28, 2021 2:46 pm
Hi. I'm not an electrical engineer and I can relate to the challenges the "every man" has when trying to do spindle control on these DIY mills. When you boil it all down, you are replacing the manual potentiometer with a "digital" version. Manual potentiometers have three terminals (Ground, Output and VCC). You feed the max voltage to VCC and the Output voltage will vary depending on where you turn the knob. You measure the Output voltage between the Output and Ground terminals.
Pretty much all manual benchtop mills have a three terminal potentiometer and if you figure out the max voltage (measured between GND and VCC) you can adjust the signal isolation board to match. The voltage measured between VCC and GND typically represents the MAX RPM of the spindle. As you lower the voltage, the spindle turns slower.
The output from the Signal Isolation board will replace the Output and GND terminals of the potentiometer. The VCC terminal is not needed and serves no purpose any more.
Long story short: The signal isolation board replaces the GND and Output of the potentiometer. It also prevents your Acorn board from getting destroyed.
Ok, so I sorted out my non-responsive spindle issue, so I can proceed!
I will adjust the pots with the #9 and #10 outputs disconnected from the Spindle to read 0v and 5v min and max.
Random question, just for my understanding.....
Knowing that I get out, exactly what I am putting in at the moment, could I simply set the CNC12 wizard to limit output to 5V and just use the KBSI as a sort of passthrough since it is already wired? I intend to use it to cut the output voltage in half as intended, but that seems like it would be an option also.
francoCNC wrote: ↑Sun Nov 28, 2021 2:46 pm
Hi. I'm not an electrical engineer and I can relate to the challenges the "every man" has when trying to do spindle control on these DIY mills. When you boil it all down, you are replacing the manual potentiometer with a "digital" version. Manual potentiometers have three terminals (Ground, Output and VCC). You feed the max voltage to VCC and the Output voltage will vary depending on where you turn the knob. You measure the Output voltage between the Output and Ground terminals.
Pretty much all manual benchtop mills have a three terminal potentiometer and if you figure out the max voltage (measured between GND and VCC) you can adjust the signal isolation board to match. The voltage measured between VCC and GND typically represents the MAX RPM of the spindle. As you lower the voltage, the spindle turns slower.
The output from the Signal Isolation board will replace the Output and GND terminals of the potentiometer. The VCC terminal is not needed and serves no purpose any more.
Long story short: The signal isolation board replaces the GND and Output of the potentiometer. It also prevents your Acorn board from getting destroyed.
Ok, so I sorted out my non-responsive spindle issue, so I can proceed!
I will adjust the pots with the #9 and #10 outputs disconnected from the Spindle to read 0v and 5v min and max.
Random question, just for my understanding.....
Knowing that I get out, exactly what I am putting in at the moment, could I simply set the CNC12 wizard to limit output to 5V and just use the KBSI as a sort of passthrough since it is already wired? I intend to use it to cut the output voltage in half as intended, but that seems like it would be an option also.