Re: [CAD_CAM_EDM_DRO] Lettering on a circular surface...

It is simplest to just do the axis substitution as if the rotary axis is
linear, and calibrate the movement for a given cylinder. This will only
work with a uniform diameter cylinder, obviously.

You can also scale your G-Code so that it works on a true rotary axis from 0
to 360 degrees. You would scale the degrees for a given segment of G-code
just like you scaled the axis (except backwards). This allows you to scale
different parts of the program for different diameters if it is not uniform.
And if you are creative with your scaling you can even use a functional
relationship for the diameter as a function of the axial length, and you can
engrave on very complex shapes. obviously your Z-axis will need to follow
the radius of the part as that changes.

99.9% of what I do with my CNC is engraving on perfect uniform radius
cylinders. I lay everything out as 2-D flat engravings and do a simple
scaling wrap around a cylinder. I, unfortunately (for you and others),
rarely use a CAD/CAM program for this since it is easier (by 1000 fold for
me) to do it with Excel spreadsheets.

Daniel J. Statman, Statman Designs
www.statmandesigns.com
dan.statman@...

----- Original Message -----
From: <flyspeck1@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, September 27, 2002 2:25 PM
Subject: [CAD_CAM_EDM_DRO] Lettering on a circular surface...


>
> There are several programs out there that will generate
> G-code for lettering. To that end, they all are
> designed to work with a normal "flat" surface. But what
> about lettering on a handwheel? To get the best
> lettering you would have the table movement limited to
> the Y-axis and a rotary axis (rotary table whose axis of
> rotation is parallel to the Y axis). Each of these
> would move in tandem with one another to create a
> character of uniform depth.
>
> My thought is that ultimately this is almost identical
> to an X/Y table movement. Not having played with a
> rotary axis, however, I don't know if they are typically
> handled differently in G-code. Logic would seem to
> indicate this is the case as your positioning is limited
> to 360 degrees. You are not, after all, moving 5", but
> rather 45 degrees (for example).
>
> So my question is two-fold. Can one simply take the X/Y
> output from existing programs and use this with a CNC in
> which the X axis has been hooked up to the rotary table
> (properly calibrated, of course). I *think* this will
> work, but of course the calibration would be a function
> of the part radius. Alternatively, is there an
> application out there that is designed to work with a
> rotary axis (which would take the part radius as an
> input parameter)?
>
> I guess this really comes down to the generic "what
> application generates code for the 4th axis, and what
> does that code look like" question.
>
> Sorry if this is a brain dead question... I have never
> played with a rotary axis before.
>
> Thanks,
> Alan
>
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