# Auxiliary high speed spindal motor on my knee mill



## KMoffett (Jun 3, 2020)

My knee mill's spindle tops out at 4K RPM. I needed more speed for tiny drills and end mills.  So looked at what other people have done. First I selected a VFD and a water cooled high speed spindle motor with an ER11 collet. The next challenge was how to mount it. There are several aluminum mounting brackets on the market for this size motor. But, how to attach it to the mill's spindle or quill? In doing a lot of head scratching and searching I came across a CAT40 mounted cylindrical, machinable blocked on eBay.  "Kennametal tool holder Blank Cat40" normally ~$250 but for $43. Bought it and milled a flat on the side, and drilled and tapped it to take the aluminum motor mount. A problem I've had in the past was that the mill does not have a spindle lock. I had made a collar that locks the spindle to the quill for a auxiliary die grinder (way too weak). Works for this too. Now I needed a way to cool the motor. A small water pump with a reservoir, a radiator and a pair of fans.  How to control it all?  I wanted a remote that could be used with the VFD for power-ON, start and stop buttons, speed control, and E-Stop. Fortunately I have a pretty good background in electronics. It did get a little involved as I figured about all the things I wanted, including linking the E-stop back not only to stop the auxiliary spindle, but also E-stop mill movement. All eventually came together to my satisfaction. See attached. I also had added a mister, and shop vacuum with Loc-Line to collect over spray and swarf.

Ken


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## Z2V (Jun 3, 2020)

Ken, nice clean job, good work.


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## Buffalo21 (Jun 3, 2020)

What rpm are you running at??


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## KMoffett (Jun 4, 2020)

Buffalo21 said:


> What rpm are you running at??


The motor/VFD will run up to 24,000 RPM.  The speed I use depends on all the usual factors.


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