Re: axis names

Thanks Fred,

I've worked through "cheating" with the rotary table connected instead
of the Y axis (the "ring" thread earlier), Which will probably keep me
busy once I get the rotary table! I take it that simple imported "word"
fonts can be engraved around the A axis quite easily, but Vfontz is a
deeper, 3D letter font, requiring the "wrap" cylinder to operate
properly?

4-axis Vector is something I want to get, but I also need to get the
table first! ;>) Then there's also the need to update the controller
program. This "axis names" thread has been quite educational. I have
two expensive (well, not cheap) CNC books, and I didn't get that much
from them on 3D. Maybe if I go back and read them again...

When I was building robots about 12 years ago, I made encoder disks for
the drive wheels using a homemade indexer. I had a large timing belt
pulley (96 teeth?), and I built a sliding "latch bolt" for it, and a
simple threaded spindle for the gear, and I could do quite a bit of
indexing. I had even planned to cut a LARGE 8" dia timing chain pulley,
for the body rotate (2'x 2' x 40h" robot). Studied the gear tooth
profile in the Machinists handbook, and calculated the arcs to cut
teeth. Didn't get that far, ended up changing jobs, and lost access to
the CNC machine that was going to do it. Could probably do it now with
an "outboard" 'C' axis (on a Sherline?).

Robots also use stepper motors, servo motors, servo drives, H-bridges,
encoders etc.! Seems to run in circles (the knowledge).

Fred Smith wrote:

> >Message: 9
> > Date: Mon, 04 Sep 2000 17:30:36 -0700
> > From: Alan Marconett KM6VV <KM6VV@...>
> >Subject: Re: RE: axis names
>
> >So what would be an example of say, A motion? I don't think I've seen
> >it in my limited researches. Do you know if FlashCut (my touchstone)
> >supports it?
>
> Nearly any 3 axis machine can utilize a rotary 4th. In a mill type set up, the Y is often disconnected and the rotary is connected in it's place. On one hand a rotary step is mechanically changed into a linear motion, and on the other a rotary step is changed into rotary motion. The only difference is how far the movement is with respect to the steps. That is almost entirely dependent on your physical hardware and most controllers will let you adjust the output to the desired scaling. Many machines also let you use all 4 axes at the same time.
>
> The rotary 4th axis is usually programmed in degrees. The most common set up is an A axis. Which is parallel to the X, since most mills have the X as the longer axis. The setup can often include the rotary axis(a rotary table fitted with a drive motor) with a chuck or collet for holding and driving the part, and a tailstock with a center for supporting longer parts.
>
> Complex programming of a rotary requires a Cad-Cam system to be of any practical use. For simple spirals, grooves and indexing from face to face on a cubic part, Cad-Cam is not required. However to program engraving, such as that generated with Vfontz, that is cut with a V-tipped cutter, you need the ability to transform the toolpath into a shape that is wrapped around an axis, and then translate that into G-code, including developing the rotational moves(A) that substitute for the Y axis. Vector's wrap cylinder function(included at no cost) does the transformation making the lettering tool paths curve around the axis (and preserving the Z relationships as radial relationships), and the rotary axis(extra cost option, ~$600) generates the complete G-code file consisting of X-Z-A coordinates. The wrap cylinder also can be used for wrapping a surface around an axis, as it retains all the Z variation as radial variation. To wrap a cone, draw the geometry at an angle in the !

X-Z

> plane (front view), it will the
> http://www.vectorcam.com
>
> Best Regards, Fred Smith- IMService
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