Re: 5-axis Taig Mill

Hi Rab,

I was thinking about programming an axis that would always be tangent,
but I don't have any immediate need. I might need to move a knife-edged
tool along a toolpath, so it might be useful there.

I was calling your 'A' axis worm drive spindle a "rotary table" when it
really isn't. Does the work of a rotary table 'tho. I use a rotary
table there, as I don't have a spindle mounted as an 'A'. Did this
start out as a lathe?

How about a "clamp" for the 5th axis? An extra Mcode could operate it.
Or, perhaps the stepper driver could do the clamping, instead of a
"reduced current" mode for the motor, you'd engage the clamp (brake).

Alan KM6VV


rainnea wrote:

>
> > 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.
>
> -----
> 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