Gantry Aluminium thickness guidance

[MikeyC38]

Hi Nick

As others have said, you do need to be more specific which you have done by showing details of your build and what you intend to cut. Rigidity is your best friend for any cnc build and as others have said plates across the end of the long axis will stiffen the frame significantly. In my build here I used 80 x 40 heavy gauge extrusions ( 4kgm+) with 15mm 6082 T6 plates either end. The gantry sides are 20mm 6082 T6 water jet cut with heavy gauge 80 x 40 extrusion for the (short) y-axis. I am very pleased with the overall rigidity but will reserve judgement until I do my first cuts on metal. It might appear over engineered but I took the advice offered on the forum and I'm confident the machine will deliver the levels of accuracy I need. The use case for my machine is cutting balsa, hardwoods and aluminium at reasonable speeds, hence the robustness of the construction for the most difficult use case (cutting aluminium).

Hope this helps

Mike

[routercnc]

I'm glad I waited for the design sketches as I mis-understood your question in the first post, now it is clearer.

Gantry end plates at least 15mm, more like 20mm to give yourself a chance with the aluminium machining. 1500x800mm is a large machine and stiffness drops considerably as you go bigger. Really I would recommend raised X axis designs for aluminium but you here now so need to recover what you can.

Long axis (I would call it X) end plates are to stop the machine ploughing off the end of the rails but you'd be surprised how powerful the steppers as when driven through the force multiplying effect of the ballscrew. You could sit on the gantry for example and it would move you around without a problem.
I would not go for 6mm end plates, but 10-15mm as a guide. Final decision would most likely be decided on if you can cut them out of an offcut plate used elsewhere as they would be quite small. The other thing to consider is they normally double up as stepper motor mounts for the X ballscrews so that will also drive the thickness.

Z axis and Y axis plates would go for 20mm personally.

[dachopper]

Hi Nick

As others have said, you do need to be more specific which you have done by showing details of your build and what you intend to cut. Rigidity is your best friend for any cnc build and as others have said plates across the end of the long axis will stiffen the frame significantly. In my build here I used 80 x 40 heavy gauge extrusions ( 4kgm+) with 15mm 6082 T6 plates either end. The gantry sides are 20mm 6082 T6 water jet cut with heavy gauge 80 x 40 extrusion for the (short) y-axis. I am very pleased with the overall rigidity but will reserve judgement until I do my first cuts on metal. It might appear over engineered but I took the advice offered on the forum and I'm confident the machine will deliver the levels of accuracy I need. The use case for my machine is cutting balsa, hardwoods and aluminium at reasonable speeds, hence the robustness of the construction for the most difficult use case (cutting aluminium).

Hope this helps

Mike

Thanks mike - 1 question,

Your gantry sides are 20mm - these are the largest plate connecting the Y and X axis, where did you use the 15mm plate for?

Any did you use plate for the Z / X axis.

I have also used high grade extrusion, the bare weight of the aluminium along for me was 76 kg. I think the Y axis was 9 kg/m, and the X axis around 5-6.

[MikeyC38]

Thanks mike - 1 question,

Your gantry sides are 20mm - these are the largest plate connecting the Y and X axis, where did you use the 15mm plate for?

Any did you use plate for the Z / X axis.

I have also used high grade extrusion, the bare weight of the aluminium along for me was 76 kg. I think the Y axis was 9 kg/m, and the X axis around 5-6.

Hi Nick

I used 15mm plate at either end of the long extrusions (x-axis) (see my build log photos for the bed construction). For the Z axis construction I used 20mm 5083 cast and machined toolplate. It has a very fine and accurate surface finish which is critical for the setup and accuracy of that axis.

Regards
Mike

[dachopper]

Hi Nick

I used 15mm plate at either end of the long extrusions (x-axis) (see my build log photos for the bed construction). For the Z axis construction I used 20mm 5083 cast and machined toolplate. It has a very fine and accurate surface finish which is critical for the setup and accuracy of that axis.

Regards
Mike

I'm trying to CAD up another concept, but Fusion360 is down on my laptop !