I've built Tom McQuire's CNC controller board but have some issues.

[Eddie6775]

Hi every one, first I did allot of digging for answers but can't seem to find the one for my question..

In case you haven't seen the insrtuctable I'm reefing to, here's the link: https://www.instructables.com/id/Easy-to-build-CNC-Mill-Stepper-Motor-and-Driver-ci/

Now, my dilemma: I've successfully built three controller boards and tested them, assembled every thing inside a nice project box and sat back proudly before the next step. Permanently hooking up the 3 DIFFERENT motors. I then realized after the two motors I left laying on the bench would not work that I had built all 3 boards to accommodate the motor I tested them with..... A 6 volt, 5 ohm per phase, 1.8 degree/step nema 17 motor. the other two are 16 volt motors and hardly move...they just hum. I don't want to put too much voltage through this circuit so I'm not sure what to do here..

Some more info. Power supply: 16 volt laptop power supply wattage unknown, and the light bulb im using as a ballast is a 14 volt screw in type from RS.

If anyone here has built this project, Input would be much appreciated! I'm sure I left something out of my question so please feel free to pick my brain.

 

[alec_t]

What is the bulb wattage? It probably needs to be increased (as suggested in the article) to allow more current through the motor coils.

 

[Eddie6775]

What is the bulb wattage? It probably needs to be increased (as suggested in the article) to allow more current through the motor coils.

just under 3. OK, so I'll try a different bulb. Thank you, I'll check back!

 

[dr pepper]

Agree with Alec, that circuit should take 16v, if you went much higher you'd need to increase R1.
So long as the fets can take the current increasing the bulb wattage is a good idea, just keep a check on the fets to see if they are getting hot, if you go much higher in wattage you'll need to clamp the fets to a heatsink.

 

[Eddie6775]

I did some reading on all of the motors I scavenged and even dug another one up out in the garage. and tried it too. It worked! I didn't think it would because it's rated for 36 volts but only has a resistance of 4 ohms across the coils. Ohm's law. go figure....I also read last night that the voltage rating is the MAXIMUM voltage, not necessarily the required voltage. I also did some home work in how light bulbs work. I was kicking my self for using the 3 watt screw in type (which incidentally fits an E 10 socket). Low and behold! the local hardware store sells 7 watt colored Christmas bulbs and they not only improved the performance of the two working motors but look nice too! lol.. I did get one small motor to run kind of choppy but it ran. I still have two more dinosaur printers to cannibalize so I might be in luck! So far so good, Thank both for your advice.

So far, this is really cool first project.

 

[alec_t]

Good to hear the motors now run.

 

[large_ghostman]

yeah that is a very cool first project congratulations! ace job

 

[dr pepper]

Once your happy with it you could replace the bulbs with a transistor current limiter, more accurate and reliable.

 

[Eddie6775]

Once your happy with it you could replace the bulbs with a transistor current limiter, more accurate and reliable.

Transistor current limiter? I'm not familiar..... Not knowing any better I'd of thought that was just a resistor. I'll have to Google that one!

 

[dr pepper]

Have a look:

**broken link removed**