Need help determining what type of spindle+motor I need.

[sburck]

Hello all,

I am looking to build or modify an existing bench top mill in 3-6 months from now. By bench top I literally mean anything that will fit on a bench / stand, from something small like a taig up to something as massive as a rf-45. What I will be mostly doing is fabricating small but intricate stainless steel parts for surgical tool prototypes / proof of concepts. Most of these parts would fit within a 2"x2"x4" space, with many of these parts being closer to 0.125" x 0.125" x 0.500" in size. These parts will be intricate, with many thin features and rounded contours. From what I know so far, work on this scale is usually done with relatively high speed spindles. There are many high speed spindles avalible, however I would like to have a spindle capable of producing enough torque to run larger end mills at slower speeds (like a 1/2" corncob rougher). Is this too much to ask for. Would I need some kind of 20 HP industrial spindle made for a highspeed haas machine or similar to get this sort of torque and speed?

[aarongough]

I'm not an expert on the metal-milling side of things (most of my work being done on routers) however from what I have seen so far you'd most likely be looking at using 2 spindles. One low-speed high-torque for the big tools and a smaller high-speed spindle for the small tools.

One solution I have seen a few times is a special air-driven spindle that mounts in the taper of the spindle already attached to your machine. I have also seen people make brackets for die-grinders so that they can attach the die-grinder to their milling head and use it as a secondary spindle.

I would hesitate to use a die-grinder as I found out the hard way that they often have lots of runout... That being said it's possible that a trim router like us wood-working guys use on our machines may work for you. Take that recommendation with a grain of salt though as this is not something I have tried with metals other than aluminum.