Ron,
I've thought more about this and came up with a few things. I don't think they'll be able to do this. Trying to interpolate two axis's with one. As the Z axis would ramp up which X feed needs to ramp with it. Say its a short workpiece. The Z ramps up to speed, now which one should ramp with it? At the end of the travel now the other would need to ramp down.
This would be a programming challenge and a half. Even with totally eliminating ramping. If they are still open to using patterns and want to do away with the hydraulics, then might consider linear encoders to follow the pattern, then a Mach system taking those inputs as MPG inputs thereby commanding each tools infeed.
Ron
Ron Ginger <ronginger@...> wrote:
Thanks for all the suggestions. Let me explain more about the lathe.
It is currently a TRACER lathe, the carriage is moved along at a steady
speed by an electric motor and rack drive. The single carriage holds TWO
cross slides, each completely independent. Both carry a tool- on the
back side of the work, so the chips fall down.
The cross slides are driven by a hydraulic cylinder, which is operated
by an index finger thats rides along a template of the desired curve.
These is only one template, the two cross slides are about 5" apart. The
template is mounted to the backside of the lathe bed, just below the
bed. Templates are made from either 1/4" ply or plastic.
To CNC it we would replace the hydraulic cylinders with a lead screw and
servo. It looks like this should be a very simple mechanical conversion-
all the needed holes and bearing mounts are already there.
The work done on this machine is architectual wood items like porch
columns, stair baulsters, bed posts, etc. It is also used with only one
tool holder, and often with a Router mounted in the tool post- this is
for doing things like roping or spiral fluted columns. All of these
applications are easy for Mach.
The real problem is we have just one Z axis, and 2 X axis. The X's each
run the same contour, but X2 is delayed by a few seconds (corresponding
to how far the Z moves in 5 inches)
I seems to me it might be possible to pre-calculate a list of X
positions corresponding to some fixed Z increments- maye even just one
per revolution of the spindle. Then to start sending a steady pulse
stream to Z, and each spindle pulse move the X to its new value. X2
would use the same table, just some constant time later. Should be a
snap with a Grex and VB. :-)
Does anyone know if any commercial machine has this ability?
ron ginger
www.machsupport.com - Web site Access
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