Novamill - Mach3

[m_c]

The PWM is connected to pin 1 on the parallel port, so it shouldn't be too hard to figure out.

[JohnHaine]

Having just installed one of those BoBs to replace the old one on my lathe, I can say with confidence that the 12v and 5v grounds are commoned! Therefore the 0-10v output is not ground isolated. Some years back I published on here a simple circuit to take the PWM output, isolate it with an opto-isolator, and smooth it to generate the 0-10V needed by Sprint type drives. A bit of searching should bring up the post.

[Deck36]

I did actually see that post and concluded that it was way beyond my paygrade currently.

Whatever the actual ins and outs of wiring/connections could or should be, the thing was working fine somehow.
I just need to get back to that somehow, then plan to update or upgrade the internals.

[JohnHaine]

Another point about these BoBs (for which documentation is very scarce) is that the logic inputs have an opto isolator with a 1k resistor connected to the +ve supply, the 12V one not 5V, and expect to see an "open collector" drive such as a microswitch pulling to Gnd or an open-collector output ditto. Caught me out and I had to convert a couple of sensors that generated a 5v logic signal.

[Deck36]

Can you suggest, based on what you've seen, which pins etc I might try to get the spindle to work?

[JohnHaine]

Sprint-Electric-340i-680i-1220i-Manual.pdf

I attach a Sprint manual which may not be for your precise type but they seem fairly generic. For a quick fix, you could either
(a) connect the speed control input on the drive direct to the +10v output they provide - that's pin 1 to pin 3. Make sure ping 2 isn't connected to anything. This will simply tell the drive to run at maximum speed when switched on.

or -

(b) wire in a 10k manual speed control pot, with the clockwise end to +10v and the other end to COM which is pin 5. Again pin 2 not connected. Make sure you have a pot with a plastic shaft, mounted so you can't touch the metal casing or screwed bush.

I can't vouch that the exact same pin numbers will be found on your drive.

[Deck36]

Nothing internally has changed with the wiring, so some combination of pins/outputs and values should surely do the trick?
I'm not in a position, time or mind wise to tackle rearranging the spindle functions and it's controller right now.

I'm going to give up the fight and get someone else to make my parts before I go completely crazy with frustration and chuck the damned thing out of the workshop

Thank you for your help. Both you and m_c have been brilliant in your efforts to educate me.

B