Cast aluminium gantry router

[jrcast]

Still haven't finished the gantry pattern as I'm flat out with work but I'm doing bits in between jobs.
I do know about shrinkage in casting, rule of thumb is 1/4" per foot,my alloy is 1-1.3%. It's accounted for in the pattern.
For anyone asking why? Here's why, I just want to cast it to see if it can be done and work.

The price of doing it in aluminium plate is crazy compared to casting it and once a pattern is made for casting you can repeat over and over. It'll all be one piece so no marking out, cutting and bolting plate together.
I can cut this to length, machine the ends then top and bottom for the rails and wherever parts are to be mounted. I might even bolt 2 castings back to back and make an "I" beam from them.

[GEOFFREY]

Watching with interest. G.

[Jonathan]

I can cut this to length, machine the ends then top and bottom for the rails and wherever parts are to be mounted. I might even bolt 2 castings back to back and make an "I" beam from them.

Don't bother with the I-beam idea - rubbish torsional stiffness.

[routercnc]

Don't bother with the I-beam idea - rubbish torsional stiffness.

True, but to pick up on your initial idea of twin beam arrangements you could arrange them like this:

[] instead of ][

[] has similar vertical stiffness to ][, slightly better fore/aft stiffness, and massively better torsional stiffness. If you cast it then you can include baffle plates at intervals so long as you also bolt through these as well.

A simpler alternative is to do |] where ] is the cast part (with optional internal baffles or ribs) and | is a simple closer plate.

Still lots of effort all round but they are possible configurations and much better than just ].