Just found this on eBay @ Tousdiamants Diamond milling machine W12 collet spindle ( schaublin aciera sixis | eBay

Attachment 6512 Already @ £82!!! an unknown quantity, so not going to buy it. However this idea seems is very much do-able.

The link I posted earlier is using an RC plane motor, These are very very grunty for their tiny size, but are still in the 10s of thousand rpm range.

A quick look at "typical" 1/4HP (180W) single phase motor on ebay gave me 220mm dia (way too big to be practical) and is as heavy as a very heavy thing. Not after massive depths of cut as max material thickness I envisage in Ally is 30mm* and maybe 2mm (maybe 5mm) in steel.

*First job will be single piece motor mounts when I can trust myself and the machine!

A 24v 200w electric scooter motor:

Click image for larger version.  Name: eBay-24v-200w-Motor.png  Views: 492  Size: 142.4 KB  ID: 6513

e scooter electric 24v 200w Motor belt drive escooter | eBay

It has a what seems like a "too good to be true" new price of just £26 on eBay and from the size of the wires is relatively diddy. It gives 2700rpm, which is in the right ballpark now! Presumably these are man enough, they lug humans around!

Main concern is with Duty Cycle, any thoughts?

So...

ER20 Long shank collet roughly £20
2 x 6004 2RS Bearings £10
Scooter motor £30
24V 10A Power supply roughly £30
Some pulleys & a belt say £30 all in (Might even have some suitable somewhere in Dad's shed
Might have material for holding bearings and making motor mounts

Downside, simply cos I wanted to do this myself...

Would need someone to do the machining for me.

With stepped pulleys, I guess wiring the motor direct to Power Supply with a switch and a link to the machine E-Stop would be fine.

£120 say £150 tops, definately do-able, especially as it would be close to "best practice" for metal.

Obviously collets to get as well, but since it's ER20 only 1 set needed if I go 2.2kW WC eventually.

Any ideas for a 240v motor, minimum power and so on?

or is the Scooter motor idea viable? Bearing in mind Steppers are also often run this way!

Cheers,
Geoff.