XXYZ Gantry
Posted by
Doug Fortune
on 2001-03-18 20:05:48 UTC
Peter Chen wrote:
XYYZ gantries exist, but you probably mean a XXYZ
gantry (the X axis is the longest axis perpendicular to
the spindle).
Yes, you are correct, often there are two separate motors
to drive the two leadscrews (or rack & pinions).
A first answer (to avoid the motors mis-aligning), is to
tie the two motors together (using a pulley, or gear).
The better answer is to have an encoder on each, but it
seems to me there is no hobbiest software to handle two
encoders for one channel.
Therefore, if you want reassurance, you should have
a 4 axis X1 X2 Y Z system, with 4 motors, and 4
encoders. The same command to X1 is always also given
to X2 (which can be done with a simple program or
shell script on the original Gcode). Thats how I'd
do it. The Kulaga/Mauch encoder feedback board
handles 4 channels, so you can use that as a basis.
Or perhaps you might elect to build a gantry with a
single X axis screw, or perhaps a bridge with a single
X axis screw.
Doug Fortune
http://www.cncKITS.com
> XYYZ GANTRYHi Peter:
>
> Good morning,
>
> Asking for opinions on XYYZ gantry. I believe this
> configuration will involve having 2 lead/ballscrew and
> 2 stepper motors for the Y axis. Suppose one of the
> stepper on the y axis lose step. Does this mean that
> the x and y axis will no longer be perpendicular to
> each other? With this arrangement how does one ensure
> squareness?
XYYZ gantries exist, but you probably mean a XXYZ
gantry (the X axis is the longest axis perpendicular to
the spindle).
Yes, you are correct, often there are two separate motors
to drive the two leadscrews (or rack & pinions).
A first answer (to avoid the motors mis-aligning), is to
tie the two motors together (using a pulley, or gear).
The better answer is to have an encoder on each, but it
seems to me there is no hobbiest software to handle two
encoders for one channel.
Therefore, if you want reassurance, you should have
a 4 axis X1 X2 Y Z system, with 4 motors, and 4
encoders. The same command to X1 is always also given
to X2 (which can be done with a simple program or
shell script on the original Gcode). Thats how I'd
do it. The Kulaga/Mauch encoder feedback board
handles 4 channels, so you can use that as a basis.
Or perhaps you might elect to build a gantry with a
single X axis screw, or perhaps a bridge with a single
X axis screw.
Doug Fortune
http://www.cncKITS.com