CNC Tool and Cutter Grinder Idea Notebook

I've become intrigued with the idea of building a small CNC Tool and Cutter Grinder based on a Sieg X2 mill. The X2's are cool little machines, and they seem to be quite capable with a little work. This is my Idea Notebook where I'll be gathering ideas and design notes to evaluate the feasibility of such a build.

The Seminal Question: How Many Axes?

We will certainly want to CNC the normal 3 axes of the Sieg mini-mill. But how many more axes are needed? One sees 4, 5, and even 6 axis tool grinders. At the very least, we need a 4th axis. That axis would be used to follow the helix of a drill bit or milling cutter. That 4th axis is rotary and can be parallel to either X or Y, but given the shape of the machine, it seems that balance might be better if it is parallel to X. I would envision mounting a CNC'd spindexer there, because they're compact and inexpensive to CNC.

A 5th rotary axis is optional, but would parallel the Z. Such an axis is very useful for putting a radius on the end of an endmill or for smoothly contouring a form tool. Imagine the spindexer 4th axis sitting on top of a CNC'd rotary table that sits flat on the mill's table and you get the idea. Ideally we would like to be able to pivot the spindex off the horizontal for some work, perhaps sharpening a tapered cutter, but that pivot need not be CNC'd.

This diagram shows the axes:

4 of the 5 CNC'd axes, plus a manual tilt axis. The gray represents the milling X and Y axis or the table and saddle.

Pictures

This is the one that finally inspired me to think in Mini-Mill terms. From the great German Metallmodellbau site...

Here is a compact industrial machine. Note the axes. Looks like a normal 3 axis mill with a head that rotates in the Z axis. It also needs to rotate the tool's axis to follow helixes...

Small machine, not CNC. Again, note the axes. Z, tool axis, in and out, and looks like a tilt rotary axis...

Simulated view of a commercial CNC T&C grinder. Gives a nice idea of the axes (this looks like a 5 axis) as well as the grinding wheel shapes that are useful...

Same simulation following the helix...

X, Y, and Z. Not much is motorized. I'd assume the controls are more for a DRO than CNC. Spindexer-style tool holder with 3 rotary axes of freedom...

The equivalent of gang tooling for a T&C grinder. Cool!

An add-on CNC T&C attachment for manual T&C grinders. There are 3 axes: X, Y, and a rotary for following the helix. This unit is very similar to the CNC'd spindexer I envision...

CNC T&C Grinder Manufacturer Links

Anca: Very high tech Australian machines with direct drive and polymer granite bases. Be sure to check out their technology brochure.