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

[Deck36]

So a long awaited update on my Novamill situation.

The day after my last post I took a call from Brian at CNC4U, where he made some suggestions to get me running again.
The one thing that helped most was to use a higher quality cable from the UC100 controller-pc. Seems there is a lot of stray EMF and cheap cables don't have enough shielding.

Combined with the help I've had here I was able to finish the project I was working on.
Once again my thanks to everyone on this forum.

That leaves me with just one issue; the limit/home switches don't work unless virtual limits are set. If I lose my initial datums for some reason (light smashing into the part) I have to start again because I have no references.

Activation lights in Mach3 show the X/Y switches working (no Z though) but when I reference the table just runs over the switches until it hits a hard stop and spins the leadscrews.

It was mentioned in a previous post that Novamill switches are inductive, so the question is; do I try to replace them with mechanical switches, or can they be made to work as they are?

My workaround idea is to add a pin or hole on the bed somewhere are a permanent reference. That way I can get back to datum if things go wrong.

Any advice would be welcome. Thank you.

[JohnHaine]

Novamill switches, on my mill anyway, are standard microswitches. Maybe there's a wire dropped off the z switch? If you are seeing the lights operate on the diag screen then the X and Y switches are working.

There's a configuration setting for the homing speed as a percentage of rapid, what do you have that set to? When the home switch is triggered the mill goes into a controlled deceleration to stop then reverse until the home switch deactivates so there is a small overtravel. If going too fast this may allow the axis to hit the end stop. IIRC I have the homing percentage set to 5% which is probably too slow but I never hit the end stops.

On another point, I almost never home the machine anyway unless I'm doing a job that is very close to the limits of travel. I always reference the axes to the workpiece using an electronic edge finder and tool height setter. If I do have a crash I only need to re-reference to the work again.

Update: the homing speed setting is in the config\homing/limits tab
Far right column.

[Deck36]

Novamill switches, on my mill anyway, are standard microswitches. Maybe there's a wire dropped off the z switch? If you are seeing the lights operate on the diag screen then the X and Y switches are working.

There's a configuration setting for the homing speed as a percentage of rapid, what do you have that set to? When the home switch is triggered the mill goes into a controlled deceleration to stop then reverse until the home switch deactivates so there is a small overtravel. If going too fast this may allow the axis to hit the end stop. IIRC I have the homing percentage set to 5% which is probably too slow but I never hit the end stops.

On another point, I almost never home the machine anyway unless I'm doing a job that is very close to the limits of travel. I always reference the axes to the workpiece using an electronic edge finder and tool height setter. If I do have a crash I only need to re-reference to the work again.

Update: the homing speed setting is in the config\homing/limits tab
Far right column.

Good advice as expected. Many thanks

I'll check the outputs and adjust the speed down to a lower value. It can't hurt to give it a try.
Reassuring to be reminded that every setup has it's own reference points, and if they are noted they can be attained after any "issues"

For anyone coming across this thread, I'd like to say this group has been invaluable with it's help and suggestions.
I can't imagine how many total years of experience is here amongst the members, but being able to tap into it is just fantastic!