4' x 4' x 8" Router Build

[JonnyFive]

Thanks Doddy, appreciate the feedback.

1. The filter is more to protect the supply (and other devices) than the VFD.... they're noisy buggers.

I see, so it's to protect things upstream of the VFD on the same mains circuit?

2, Correct

3. Closed-loop makes no difference. Whether you're driving high or low is largely irrelevant (the two pins are the anode/cathode of an internal LED used for isolation - so switching either works). What this gives you though is flexibility - for example an open-collector (open drain) drive is designed for low-side switching (i.e. take the + to supply, and switch on the -). The axbb manual describes the non-isolated outputs as being able to push/pull 20mA - so can source (+ve) or sink (-ve) - so can drive either input.

Thanks for the explaination, I'll leave them as they are.

4. Your call. It's better to cut to length but not if you risk damaging anything.

I'm fine with cutting them to length.

5. Yes. Unequivocally. Do I?, I might.

I'll add one in.

6. I only glanced at your schematic - it feels a safe design but more than I'd do for a personal machine. I can't knock safe design but I can duck an errant shock 50% of the time.

I'm still in 2 minds, it looks cool but isn't really doing anything that the switch on the mains socket doesn't do other than stop you going in the cabinet which I wouldn't do.

7. It's a good idea. Otherwise a stray wire in the spindle could short to the enclosure and zap you. Of course your protective earth will then ensure that you brick your VFD before your blow the protective devices.

Easily solved, I can add it. I've also seen people saying you need to open up the spindle and check that pin 4 is actually connected to the spindle body, I'll check this too.

8. No. Unconnected, the LED opto-isolator remains inert and the drivers enabled.

9. It's a good idea, but realistically will achieve little. You'll be generating pulses at maybe 100kHz at around 5mA, that will generate some EMF but I'd hazard a guess that you're not going to impact much. The driver inputs going through an opto isolator will be pretty tolerant of any induced emf.

I'll do it anyway.

10. Yes, in fact I have insulated ferrules that accept two cores (i.e. a wide rectangular receptacle rather than round), Use common sense - if the cores fit comfortably then there's nothing wrong. Test each crimp.

11. I'd go for the permanent supply, otherwise you can end up with pull-lows on outputs when you don't intend this (remember, you still have a 0V supply to the AXBB, it's capable of hard-driving low). But remember I've not really looked at your schematic.

I don't fully understand what you've said but will swap to the permanent 24V supply - sounds like it's the way to go.

[Lee Roberts]

I've also seen people saying you need to open up the spindle and check that pin 4 is actually connected to the spindle body, I'll check this too.

You could probably check this with a multi meter rather than take it apart and brake any seals etc...

[JAZZCNC]

#4 Depends on the quality of the wire, the wire on the Lichuan motors we use isn't shielded and we never have any noise issues from it, only on very long wire runs ie: 8x4 or 10x5 machines do I tend to fit shielded cable but even then it's only precautionary thing and I doubt would have trouble based off the other machines we built.

#7 We don't connect this as it's given me problems in the past with noise, if the chassis/gantry is earthed then you won't have any issues.

#11 Permanent 24v and 5V supply otherwise you'll drop power to the Axbb-e and lose your Workoffset if you haven't saved it first, UCCNC only saves the Workoffset on shut down so if you haven't saved the offset then it will be lost with a power cut. It's also a pain in the arse having to restart UCCNC, reload the G-code etc just for an E-stop.

[JonnyFive]

You could probably check this with a multi meter rather than take it apart and brake any seals etc...

Thanks Lee. I have done a continuity test and can confirm pin 4 is connected to the spindle housing.

Cheers

[JonnyFive]

#4 Depends on the quality of the wire, the wire on the Lichuan motors we use isn't shielded and we never have any noise issues from it, only on very long wire runs ie: 8x4 or 10x5 machines do I tend to fit shielded cable but even then it's only precautionary thing and I doubt would have trouble based off the other machines we built.

I'm assuming this is something I could easily upgrade if the need arises once I'm up and running? The cables I have came with 3m extension cables, hopefully these will be long enough.

#7 We don't connect this as it's given me problems in the past with noise, if the chassis/gantry is earthed then you won't have any issues.

OK, I'll leave it un-connected. The cable from the VFD to the spindle needs to be shielded but with the shielding only connected at the VFD end and not to the spindle connector - is this correct?

#11 Permanent 24v and 5V supply otherwise you'll drop power to the Axbb-e and lose your Workoffset if you haven't saved it first, UCCNC only saves the Workoffset on shut down so if you haven't saved the offset then it will be lost with a power cut. It's also a pain in the arse having to restart UCCNC, reload the G-code etc just for an E-stop.

I'm referring to the 24V to the isolated inputs, the 24V and 5V power connections to the AXBB-E are permanently connected. Should the isolated inputs be permanent too?

Cheers

[Lee Roberts]

The cable from the VFD to the spindle needs to be shielded but with the shielding only connected at the VFD end and not to the spindle connector - is this correct?

Yea and do the same with the control/comms wire to/from the vfd, except connect that earth to your main star ground in/at the cabinet end.

No ground loops etc...

[JonnyFive]

Yea and do the same with the control/comms wire to/from the vfd, except connect that earth to your main star ground in/at the cabinet end.

No ground loops etc...

You mean the wires going to DCM / FOR / ACM / VI on the VFD?

[Lee Roberts]

You mean the wires going to DCM / FOR / ACM / VI on the VFD?

No, sorry I meant to say shielding not earth, but yes the shielding for that group of wires, not the connections themselves...

So I'm talking about the control wire you would also install so that the main cnc controller can control your VFD from software.

Also, I think you should choose Doddy's advice and mine on this one and definitely connect Pin 4, it costs nothing to do and I too would rather sleep well at night knowing your/my spindle housing is properly wired to be safe in a fault condition.

Earth/ground is there for safty first and should be used as intended, using it for noise drain should be considered as a secondary bonus feature in this application in my opinion.

Noise issues can be isolated and remedied, restarting your heart isn't as easy to do...

[JonnyFive]

I have updated the schematic:

• Earth wire from VFD to pin 4 on spindle added.
• VFD to spindle cable screened with screen attached to ground.
• DCM / FOR / ACM / VI wires all screened and earthed.
• Isolated inputs connected to permanent 24V.

CNC CIRCUIT DIAGRAM V4.pdf