[Thermal]

Originally Posted by sanddrag

A router is certainly the cheapest option, but I'd be worried it's RPM would be a little fast, it's bearings might not last for heavy milling in aluminum, it probably wouldn't take larger endmills, and it would be really loud.

There's this spindle but it's not cheap and a little on the small side. Also, it could stand to be a little faster. Nice thing is, it's a complete unit and it's R8.

You could use a Tormach spindle assembly which is pretty nice (they have two different ones), but it would run you about $1100. It's a bit large. I'm not sure how it would fit in with the scale of your machine.

I'm not aware of any other spindle assemblies for sale separately. You could contact some mill manufacturers though such as Industrial Hobbies or LatheMaster and see if they'd be willing to sell you just a spindle assembly.

Of course, with all of these options, you'd still need a Z-axis.

Wood routers are quite capable of sheet aluminum work but you have to get a little creative about it. http://www.vhipe.com/product-private/SuperPID.htm is a great tool for that.

You're correct about the bearings though, heavy aluminum work will destroy wood router bearings in a few months. Handily though, replacement bearings are relatively cheap and not too difficult to replace.