Aluminium FEA optimalized CNC router

[PotatoMill]

Now the whole thing begins to come together again. I have done some more FEA on the whole frame. I will just add that they are approximations and gives a rough overview. Joints and mounting points will add to the deflections.


Base:
I did some test with and without the side supports. The side supports make the base a lot more rigid. However, without the side support the deflection on the base is still insignificant compared to the gantry and the y and z carts. I also looked at how steel would increase the rigidity, but since the deflection on the base already was insignificant on the total frame, the increased stiffness from the steel was very small on the whole frame. The base is about 57kg with aluminum and 105kg with steel.

Gantry:
The gantry have a lot to say on the stiffness of the frame especially torsion that add to deflection on loads in the x axis. The gantry is changed from a frame with a lot of 60x60mm square tubes to a single 300x200mm t=6 rectangular tube. The stiffness of the new setup is about the same, but it makes the assembly a lot easier. Which means there is less areas to make mistakes the rigidity of the machine will suffer from. I had to go for steel on the gantry to get it rigid enough, an aluminum rectangular tube was just not enough. Casting aluminum could be possible, but that will again make it more complex and prone to errors. The gantry is still movable on its own, but it is now at 50kg. The Y and Z cart is at 20kg so in total the gantry and Y and Z cart will be 70kg.


The design on GrabCad is now updated https://grabcad.com/library/z-and-y-cart-gantry-cnc-1. However, the ball screws for moving the gantry is not finished yet. And I see that mounting of the rails for the Y cart makes it impossible to attach the Y cart so I have to find a solution for that. Moreover, it would be great if someone have a good suggestion.