Quote Originally Posted by m_c View Post
Space is certainly a challenge with triac spindles.

Andy, what is wrong with your spindle motor/drive?
Mine started hesitating and making what's probably best described as a rumbling noise, followed by tripping the RCD at higher speeds. I took the brushes out, and there's signs of arcing on one of them, and another was sticking in the holder, but giving them a clean never made any difference.
The armature isn't that clean looking, however I won't be able to get the motor apart without using heat to get the pulley of, and I suspect the real problem lies with the drive. For it to trip the RCD, there's either got to be an excess build up of carbon inside to give continuity between the brushes and the case, or the SCRs on the drive are starting to breakdown and shorting to GND.
From past experience with my old lathe, the rumbling noise is consistent with a faulty drive.

If you want a new replacement DC drive, KB Electronics drives aren't that expensive. For basic speed control, a KBIC would work, or if you want to keep the tacho feedback, a KBMM would be needed. You'd also need to add the extra heatsink for either option to get the rated power capacity.
Axis Controls are one of the UK distributors, who I'd happily recommend as they've always been helpful when I've used them - http://www.axiscontrols.co.uk/shop/kb-electronics-dc

I think I'll go and start a new thread about my replacement plans, as I'm umming and arring over the design.
These are around £270ish new. The 1220i which is 12A, isolated input.

http://www.sprint-electric.com/products/340i

Im selling my one that I no longer need for £100 if interested. Din Rail mount, nice and tidy.