Quote Originally Posted by BikerAfloat View Post
Excellent Wilfy, you have totally understood where I am going with my questions!
I think everyone participating in this thread understands where you are coming from since you have already made it perfectly clear. Jazz and I are just attempting to make sure you know the advantages and disadvantages of every option.

The absolute maximum price you can go to is already less than the cost of the 1.5kW ER11 spindle, hence you're going to have to wait to get a spindle anyway so all it would gain is getting the better spindle slightly sooner then some time in the future regretting not being able to use any cutters above 7mm. Consider also the cost of the cutters as that could make up the differenc. 1/2" router cutters have a large market, hence they are cheap. In addition the power from the spindle (roughly) decreases linearly from maximum power at around half rated speed to zero at zero rpm. You'll probably never use 1.5kW, let alone 2.2kW, but because of this relationship it's important to have the higher rated power to maintain enough power at low speeds.
Hence you will find it harder to use the 1.5kW spindle at low speeds - i.e. harder to cut steel or drill aluminium.

3) The VFD will let you set whatever speed you want - it's the control algorithm and ratings of the spindle that dictate how fast the spindle will run. The 8000rpm minimum you read might have been referring to the air cooled spindles which cannot be operated at low speeds since the fan would not provide sufficient airflow to cool them.