We get a lot of requests for a taller gantry on our machines. While we extend the riser extrusion to provide a taller gantry on our PRO Series Machines
, there are several things to consider before going this route.
The z-axis is typically the weak link in any gantry style machine with a moving z, as this is the only cantilevered axis (supported on only one end) in the system. With a taller gantry, the z axis needs to extend farther to reach the work bed. For a cantilevered beam, stiffness is a function of the inverse of the axis length cubed, so even a slightly longer z can make the axis significantly less stiff, which can lead to deflections in harder materials and increased vibration while cutting. For materials like foam and balsa, this is less of a concern, but if your main cutting will be in wood or aluminum, cut quality can suffer significantly.
A longer z-axis often requires extremely long tooling to fully take advantage of the travel, especially if there are steep concave portions in your design where a router body cannot fit. These tools can be very expensive and can suffer from vibration issues.
In most instances, the desire for a longer z is because the final workpiece is taller than the standard travel we offer, but there are alternatives to a longer z travel:
- Layering The first strategy we suggest is to cut your part in layers, with CNC'd indexing holes to align the layers. This requires far less z travel, and also removes risk by turning a long machining program into more manageable segments. It can also allow you to add undercuts or other features typically not available in standard 3-axis machining if the layers are segmented properly.
- Lowered bed. In some cases, while the workpiece itself is taller than the standard travel, the actual height delta of contours in the piece is less than the z travel of the machine. In this case, rather than extending the gantry and z travel, more room can just be provided for the workpiece. We can potentially customize the frame of your machine to provide a lowered table if your application requires this.
If you have parts that require a taller gantry, we're happy to discuss the best way to accomplish this on your machine. Just drop us a line
and an applications engineer can walk you through various options.