View Full Version : Triangular gantry design - opinions wanted

andrew 2000
20-12-2015, 08:44 PM
Hi everyone, I'm building my first machine and would appreciate some feedback on the following gantry design and whether you think it would work well as a design for cutting aluminium on a high sided cnc router.


The gantry will be about 1000mm wide, 200mm high with a 200mm base. I would use either 10 or 5mm T6 aluminium for the triangular section.

The reason I think it would be very stiff and resist twisting very well is because forces applied to the top edge would be transmitted down the angled panel to the linear carriages attached to the base. This would make back and forth and up and down movements of the top edge very difficult. The bottom panel would resist bending in the horizontal direction due to its depth and the vertical panel would resist bending in the vertical direction due to it's height. This combination would I think be very strong and also quite light as it only has three sides as opposed to the usual four, but I'd be interested in some opinions from experienced builders because I don't want to do something silly.

Also, would 5mm plate be thick enough or is 10 better

Thanks in advance

18-10-2017, 10:40 PM
The root cause of main deflection on gantry machine is twist of gantry itself. It must be very stiff... This is the reason why it is not usual design for metalworking machines.

Think about mineral cast instead of beams. Weight-wise approx same, cost-wise probably same..., stiffness-wise much better, (also for Z beam)...