Spindle Speed Controller for HF 44991

Hi all. I am doing a CNC conversion on my Harbor Freight 44991 mini mill and I want to add a spindle speed controller so that I can change direction of the spindle as well as change speed using Mach4. I have been searching for days to find a controller for this but I am unable to. The best I have found is here: https://www.ocf.berkeley.edu/~davyto...bies/mill2.htm but there are no directions or schematics to assist me in building something.

So, does anyone build, have plans, or know of how I can get control of the spindle speed and direction so that I can use the Mach 4 software in its full configuration?

If I understand this correctly, all I will need is a digital POT to control the speed RPM, and a digital switch to control the High/Low speed switch, and a digital switch to control the on/off switch of the spindle (not really required I guess).

Any help appreciated. I have done many many a search and have not found anything on this.....

I would recommend a CNC4PC spindle speed controller board, some specifics (what is your motor control board xmt or xxx etc/) are in order. I'm working on a similar mod.

Chelsi

Using 2 4n26 optoisolators.
I'm using a 5axis green board with blue relay BOB (Breakout board) off a UC100 USB cnc controller and Mach3.

Harbor Fright 44991 w/ LMS belt conversion and CNCfusion $629 CNC kit, using JMC-motor.com iHHS60-36-30 (NEMA24 -- 49mm between holes, 24-48v 3Nm 428ozin) the CNCfusion used NEMA23 47.14mm bolt pattern. So my motors are rotated a bit and new M5 holes drilled and tapped.



From your BOB you need PWM, usually p1 (pwm) of lpt port, spindle on can be linked to P14 (enable)

The solid state relay is switching pin 3 to pin 5.

You can steal 12v off P1 and ground from P3.

for PWM:
P1 to pin 5 of the first 4n26, P2 to pin 4 with a 4700 ohm resistor between P2 and P3.
From the BOB pin1 (BOB1) to pin 1 of first 4n26. pin 2 to a 270ohm resistor to BOB ground (over with pins 10,11,12,13,15 connector)



For Motor enable:
To control your solid state relay, P1 (12v) to pin 5 of 2nd 4n26, P2 to pin 4 with a 4700 ohm resistor between P2 and P3.
From the BOB pin14 (BOB14) to pin 1 of second 4n26. pin 2 to a 270ohm resistor to BOB ground (over with pins 10,11,12,13,15 connector).

So a 3 wire pin 1, pin14, and ground from control box to BOB.

adding reverse is a bit harder. finding a DPDT relay with a 12v coil with a 4K or higher coil (you want a max of 50ma going through optoisolator 4n26).
makes for a 4 wire BOB to controller cable and adds 3rd 4n26 in the controller.

To control motor direction, P1 (12v) to pin 5 of 3nd 4n26, one side of relay coil to pin 4 with yet another a 4700 ohm resistor between pin 4 and P3, other side of relay coil to P3.
Motor M1 to relay circuit 1 common.
Motor M2 to relay circuit 2 common.

Jumper:
Relay Circuit 1 throw NC to Circuit 2 throw NO.
Relay Circuit 2 throw NC to Circuit 1 throw NO.

Make sure motor is stopped before changing direction or you have to make a circuit to switch in a braking resistor for a time then switch direction and same thing other direction.

Controller M1 and M2 to circuit 1 NO and circuit 2 NO



From the BOB pin16 (BOB16) to pin 1 of 3rd 4n26. pin 2 to a 270ohm resistor to BOB ground (over with pins 10,11,12,13,15 connector).

if P1 doesn't supply enough current. add a 12vdc supply with the ground tied to P3.


Check to make sure P1 is 12vdc positive!

I'm working on a single sided circuit board that you can cut on your mill. My PCB will also support a braking resistor diode snubber and relay with a time delay before switching... Still designing the circuit..



[QUOTE=New Lathe Man;2001664]Hi all. I am doing a CNC conversion on my Harbor Freight 44991 mini mill and I want to add a spindle speed controller so that I can change direction of the spindle as well as change speed using Mach4. I have been searching for days to find a controller for this but I am unable to. The best I have found is here: https://www.ocf.berkeley.edu/~davyto...bies/mill2.htm but there are no directions or schematics to assist me in building something.

So, does anyone build, have plans, or know of how I can get control of the spindle speed and direction so that I can use the Mach 4 software in its full configuration?

If I understand this correctly, all I will need is a digital POT to control the speed RPM, and a digital switch to control the High/Low speed switch, and a digital switch to control the on/off switch of the spindle (not really required I guess).

This breakout board

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

has a 0-10V analog output that can be connected in place of the original speed controller's potentiometer.

Original speed controller is 0v is max speed and 12v is 0rpm. 10v won't stop it.

Quote:

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Originally Posted by New Lathe Man

Hi all. I am doing a CNC conversion on my Harbor Freight 44991 mini mill and I want to add a spindle speed controller so that I can change direction of the spindle as well as change speed using Mach4. I have been searching for days to find a controller for this but I am unable to. The best I have found is here: https://www.ocf.berkeley.edu/~davyto...bies/mill2.htm but there are no directions or schematics to assist me in building something.

So, does anyone build, have plans, or know of how I can get control of the spindle speed and direction so that I can use the Mach 4 software in its full configuration?

If I understand this correctly, all I will need is a digital POT to control the speed RPM, and a digital switch to control the High/Low speed switch, and a digital switch to control the on/off switch of the spindle (not really required I guess).

Any help appreciated. I have done many many a search and have not found anything on this.....

---

Did you ever get this working?

I had one of those except it was sold by Grizzly. Its a DC motor so you will need to deal with that. Since its Chinese design and made you might be better off looking for an existing controller interface. Did you check with Little Machine Shop dot com?