[pbb116]

Is 1/4 aluminum thick/rigid enough for my z axis plates.

[ger21]

Depends on the overall design of the machine, but generally, I'd say no. Mose people use 1/2" to 3/4", or even 1" on larger machines.

[jones]

I'm going 10mm on mine because it's what I have available, and I'll be putting 6mm stiffener plates on the sides to increase rigidity. I'm expecting it to be alright because the FEA software says it will actually be more rigid than a solid 16mm plate, but I'm prepared to have to upgrade it at a later date if it's not suitable.

As for a 6mm plate with no reinforcement I'd echo Gerry, probably not OK.

[wizard]

I wouldn’t go that thin even on a PCB engraver.

[pippin88]

I'm going 10mm on mine because it's what I have available, and I'll be putting 6mm stiffener plates on the sides to increase rigidity. I'm expecting it to be alright because the FEA software says it will actually be more rigid than a solid 16mm plate, but I'm prepared to have to upgrade it at a later date if it's not suitable.

As for a 6mm plate with no reinforcement I'd echo Gerry, probably not OK.

This is the best approach. Flat plates are flimsy.

[wizard]

This is the best approach. Flat plates are flimsy.

Also you can find Aluminum channel extrusions or even steel channel that would reduce the machining and assembly effort. It might take a bit of looking because you will need to find something wide enough in the drops section of your metals supplier or pay through the nose for a piece of prime cut to length. Cutting off the flanges from an H beam is also a possibility.

I just wanted to point out that there are multiple ways to address the flat plate problem. Most of these will help keep the weight down compared to a flat plate thick enough to give similar performance.

Also the amount of unsupportted extension is a factor. Even the spindle mount can effectively stiffen the mounting plate. In general though 6 mm is thin for most routers.