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Now that I've got the hardware/software basics sorted for the CNC, I'm pondering the choice of spindle/motor to install on there. I currently have a Bosch 1617 in the plunge base, a Triton 3HP in the table, and a trusty 690 in a fixed base (in addition to the PC310 in the binding jig), but I'm thinking a spindle might be a better option. I'll primarily be doing woodworking on the machine (duh), with very occasional aluminum milling, and I also want to be able to do high-precision stuff like inlay and fret slotting - staying within machine capabilities.

Right now I'm looking at the 2 and 3HP (1.6 and 2.0 kW) Teknomotor spindles (Italian, have a local distributor with good prices), also having a peek at various HSD offerings if I can find someone actually selling the darn things. Not cheap, coming in at around 1100 euros including VFD and collets (and 19% VAT), but lower noise will be much appreciated by all, including the neighbors.

Are these spindles the most suitable option for the precision work as well, or should I be considering a second higher precision spindle for the fine detail stuff?

The units I'm looking at (leaning slightly towards to 1.6 kW unit due to price and weight - 15.5 lbs vs 19 lbs, and about 250 dollars difference in price when considering VFD and spindle itself). Both units do 24,000 rpm top speed, and take ER25 collets. Any thoughts on power requirements (will the 400 watts really be necessary?)? I may start doing small-scale production work, but we're talking weekends and evenings only, so in reality it's more like large-scale hobby work.

One more thing I can't quite figure out with ER collets is many places state that any one collet size will tighten up to 1 mm. Does this mean I can use a 13mm collet for my 1/2" router bits (12.7mm), and a 4mm collet for 1/8" bits (3.17), or should I 'simply' get proper imperial collets? Any recommendations as to where?

Lots of guys are using small cutters in woodworking/light duty spindles, I don't think you'd need anything else. I wouldn't want to run them in a router, but a spindle would be fine.

So far as collets go, they can squeeze a bit below size. For your main cutters (1/2"), I'd get a collet that fits perfectly, but I use the nearest 1/32nd-incremented collet for different sized drills or the rare occasion I need a metric mill. I'd say they're good for maybe 1/2mm tops out of spec, though, not 1mm for sure.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services