Re: 5-axis Taig Mill

> What resolution do you need on the 5th axis (around pivot)? How

about

> mounting the spindle on a 3" or 4" timing belt pulley, and running

that

> from a stepper? That would be somewhat smaller, and quite a bit
> lighter. Although you wouldn't have the back-gearing (worms don't
> back-gear) of the worm gear to keep it solid.

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I'm not sure what resolution I really need for the 5th-axis, most of
my work is low precision stuff, but repeatability is important.

The timing belt and pully approach is one I've thought about, but as
you say, I don't know if it would end up solid enough, maybe with a
heavy duty belt and a high ratio between the pully and stepper and
keeping the tooltip and hence cutting forces at or near the pivot
point ???

>
> And it looks like you run the work in a second worm-driven spindle
> mounted as an 'A' axis? Wouldn't you want to run the rotary table
> there? (you have two now?).

Just got the one rotary table I'm afraid, but if I find a better
means of rotating the 5th-axis then that rotary table will end up on
the 4th-axis ( it's got lower backlash than my own homebrew effort )

> Quite involved! I can't imagine how to develop the toolpaths!
>
> Alan KM6VV

The main thing is finding the angle which is the 'normal' direction
to the object you want to machine for every point on the toolpath,
the rest is just working out where all the axes have to move to in
order or the tool to approach the surface at that angle.
I drew the basic dimensions and movement of the Taig into the same
program I use for design and toolpath creation (3DS MAX) so I can see
how the machine is going to move while the final toolpath is being
generated, that in itself has made things a lot easier for working
through the above procedure.

Rab