Gantry Aluminium thickness guidance

[dachopper]

Take 2,

I'm still not happy about having to put all this stuff on the k2 relay, but I can't seem to figure out any other easy way.

[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 !

[JAZZCNC]

End plates for a gantry? So what happens when you accelerate the head hard along the gantry or the tool plunges in to the side of something resilient? That is the moment you realise that a plate simply does not cut the mustard and you really needed to think in triangles.

Another really helpful comprehensive post robin from your Vast experience.!! . . . . Why don't you just shut up if can't give relevent and helpful comments.

You didn't even think to ask about Style of router and what his uses for it where.! . . . The design he's using will work fine for his needs and his question for plate thickness is perfectly valid with this design.! . . . He didn't need sarcastic pointless reply about triangles when all he asked was for plate thickness for Gantry sides.

60 views and no advice, someone must have an idea

It's long way to OZ there's time delay.!!!

I build similair design and depending on the Gantry side heights either 15 or 20mm will work. The Red machine uses 15mm sides but as lower sides. White one uses 20mm.
Like wise the Red machines uses Z axis with Rails on the front plates like has been suggested. However the White one is the other way around.?

Reason for this is down to usage. The red machine was designed just to cut thinner material upto 75mm. It will happily cut upto aluminium.
The white machine had requirement to cut deep material with long tools in Clay model board which isn't very hard material. This required the spindle lifting higher to allow for long tool hence rails on back plate.
Both machines will happily cut aluminium with light cuts, infact the very first Job the customer cut was 4 x aluminium plates for where the machine fastens to the base frame which you can just see on one of pics where machine meets frame.(I only supplied the machine)

Me personaly I would use 20mm every where, even Z axis. Also with Z axis if don't need long tools or deep cuts then would always go with rails on front plate.

Regards the frame and gantry then I'd consider a few bracing plates like been suggested. . . . Hey maybe even cut them in triangle shape.!!

With little bit of bracing then this design will easily do everything you asked about. Aluminium work will require lighter DOC cuts but will still handle it no problem.

Good luck and keep it up.