2.2kw spindle Heating Up

[Neale]

I found that I could run my 2.2kW spindle uncooled at about half-speed and light cuts for about 15-20 mins before it became hot enough that I was unhappy to continue - at that point it was still just cool enough to touch but probably somewhat warmer inside. I use a cheap caravan water pump that cost about £12 from eBay (and I'm sure that everyone else can buy them for less - story of my life...) and with a few metres of plastic pipe and a bucket, it makes a very effective cooling system. The pump instructions say do not run for more then 15mins continuously; because my control box includes an old PC power supply I have both 5V and 12V available. I fitted a two-way centre-off switch so that I can give a quick blast of 12V to purge odd air bubbles, and then go to 5V and it seems to be happy to run for hours like that.