To allow the Gantry Mill to take much heavier cuts, we stiffened the X-axis considerably, and redesigned the columns of the gantry assembly to improve stability and rigidity. The forward-most X-axis linear guide trucks are now well in front of the bridge, moving the center of gravity back, so the X-axis trucks are more evenly loaded. Also, there are now four linear guide trucks per side, and each truck has a higher load rating than those on the gantry router series machines.

The highlight of the GM-2 is its powerful 30 hp (22.4 kW) inline direct-drive spindle. This is the same high-performance spindle used in our VF, EC, and UMC Series mills – now available to tackle your biggest jobs on this large, open-frame machine.

The GM-2 comes standard with an 8100-rpm spindle that is outstanding for all-purpose machining work. For high-speed machining operations and high feedrates with small tools, optional 10,000-rpm and 15,000-rpm high-speed spindles are available. These spindles are capable of high rpm operation, without sacrificing low-speed torque or high-speed power.

The GM-2 also incorporates the robust spindle head assembly from our highly successful UMC-1000, which uses linear guide trucks with a much higher load rating for added rigidity, transforming our very successful large-frame gantry router into a high-performance gantry milling machine.

This change also means that high-productivity options like Through-Spindle Coolant and Through-Tool Air Blast are available on the GM-2.

Increased spindle power and rigidity mean nothing if you can’t push the cutter through the material. So, we stiffened the GM-2’s gantry, column, bridge, and spindle head assemblies to handle the additional forces generated during heavy cuts, and then added a second X-axis ballscrew/motor assembly to increase the axis thrust.

The GM-2’s X-axis thrust increased 80% to 4500 lbf (20,017 N), and the Y-axis increased 60% to 1650 lbf (7340 N) – more than enough for heavy cuts and fast material removal.

With the addition of the spindle head casting and spindle motor assembly from the UMC series models, we were able to easily increase the Z-axis travel over the gantry router models.

In fact, we effectively doubled the Z-axis travel from 11" (279 mm) to 22" (559 mm).

Additionally, we increased the spindle nose-to-table dimensions to allow more room for the typical workholding used in milling applications. The minimum nose-to-table dimension increased from 2.5" (63.5 mm) on the GR-712 to 4" (102 mm) on the GM-2. The maximum nose-to-table dimension increased from 13.5" (343 mm) on GR-712 to 26" (660 mm) on GM-2.

The GM-2’s free-standing control pendant on wheels allows the operator to move the control to any convenient position, rather than have it permanently attached to the electrical panel at the end of the machine, like the gantry router models.

The machine also uses more convenient contact safety sensors, rather than the light curtain sensors found on the GR series. Now, you can step close to the machine without triggering a feed-hold condition. You actually have to make contact with the safety sensor to trigger a feed-hold. This allows the operator to safely work on the table away from the machining area, without tripping the sensor.