This is for anyone looking to reduce noise and improve low speed cooling for cheap Chinese shaft fan "air cooled" spindles.

I had to replace a broken electric fan on my PDS spindle recently. I opened it up expecting to find some proprietary super duper cooling mechanism (given how much they charge for electric fan models). And I found this:

A relatively cheap off the shelf 24v 26w Ebmpapst 80mm x 80mm fan. $62 off ebay (new). It's just bolted to the lid of the spindle with 3/4" spacers.

Opening a CNC spindle is like meeting your heroes. Disappointing... not nearly as much magic in there as some think...

But, it's extremely easy and inexpensive to remove a noisy shaft fan and put one of these in your spindle instead. Obviously you need room in your spindle for an 80mm square device.

This guy did just that:

Now his $250 Chinese spindle runs as quietly as the $2500 brand name electric fan spindles. He went from an ear busting 110db to 80db.

My spindle is a 5.6kw 24,000 rpm model so this fan is good for anything up to that. I saw some of the 10kw HSK spindles used a 100mm 37w Ebmpapst fan.

One point to note is that electric fans can be delicate. Don't expect one to last forever if you cut aluminum. Damon CNC offers a pneumatic cooling upgrade which I plan to buy if they are ever back in stock again: