Just an idea, I may be bonkers......

[Voicecoil]

Denford never used shielded wiring to stepper motors, and it's never caused them any problems.

Having the drivers at the motors is nothing new, but it's not something I'd personally want to do unless the step/dir were using differential signals.

I can see that as long as your limit switch wiring is well shielded then it shouldn't be a problem as far as the machine is concerned. However I'm conscious that I have some short lengths of the original unscreened cable of the limit switches in use (WHY don't they cable them with twin screened rather than the pissy miniature 3 core stuff???), and besides which I would like to be able to listen to the radio interference free whilst I'm working!

[m_c]

I can see that as long as your limit switch wiring is well shielded then it shouldn't be a problem as far as the machine is concerned. However I'm conscious that I have some short lengths of the original unscreened cable of the limit switches in use (WHY don't they cable them with twin screened rather than the pissy miniature 3 core stuff???), and besides which I would like to be able to listen to the radio interference free whilst I'm working!

In my Triac, the only shielded wiring were the original spindle motor tacho wires, and one of the tool carousel sensors. Everything else is unshielded, and runs in the same cable tracks as power wiring.
However, Denford always used 12 or 24V for control wiring, so noise should never be a problem.

Given the amount of effort it takes to properly and reliably shield wiring, I'm surprised more people don't use higher voltage signal wiring.

[Kitwn]

and besides which I would like to be able to listen to the radio interference free whilst I'm working!

VHF-FM is likely to be more interference free than MW-AM and DAB better again. Having spent 21 years as a BBC Transmitter Engineer before moving down under I'd also like you to be able to listen to the radio interference free whilst you're working.

Kit

[cropwell]

VHF-FM is likely to be more interference free than MW-AM and DAB better again. Having spent 21 years as a BBC Transmitter Engineer before moving down under I'd also like you to be able to listen to the radio interference free whilst you're working.

Kit

After 21 years as a T-E. I'd have thought you had had enough of radio interference and not needed to listen to it at all, even though it is free !

Rob-T

[Kitwn]

After 21 years as a T-E. I'd have thought you had had enough of radio interference and not needed to listen to it at all, even though it is free !

Rob-T

One of the problems of being an engineer in that field is you can be more aware of the technical quality than the program content.
I was very much a talk radio man, R4 and the World Service were my favourites, but rarely watched television. I spent the last 16 of those years as a lecturer at the BBC's technical training school and was known for saying of TV "I teach people how it works, I'm not obliged to watch it". I usualy had (still have) no idea who people were talking about when discussing programmes. Unless it was David Attenbourough of course.

Voicecoil,
If you're going to be THAT determined even the power of Auntie will have to give in.

[Voicecoil]

It was entirely unintentional, and indeed a problem that took quite a bit of shielding (including a screened speaker lead!) to solve. So were you at Wood Norton then? A couple of colleagues of mine went through courses there, just the best training on the planet at the time: shutting it down/farming it off was probably the worst thing the BBC has done.

[Voicecoil]

VHF-FM is likely to be more interference free than MW-AM and DAB better again. Having spent 21 years as a BBC Transmitter Engineer before moving down under I'd also like you to be able to listen to the radio interference free whilst you're working.

Kit

That's entirely logical, but it's perfectly possible to knock out VHF-FM. A few years back I was designing a class D (PWM) audio power amplifier which ran on similar power rails to an 80V stepper driver and with a not dissimilar switching frequency (about 300KHz IIRC). In spite of the pretty massive LC output filter, with a lead running to the loudspeaker consisting of a couple of pieces of 1.5mm2 twisted together it completely obliterated VHF reception in the workshop.