Aluminium adhesive

[EddyCurrent]

Same question myself, there seems to be plenty of choice re. adhesive but as you say first hand experience feedback is required.

[GEOFFREY]

Don't know about adhesives, but I think welding will cause even greater distortion than with steel. G.

[C_Bubba]

When I built my router (primarily to make PCBs) out of aluminum, and not having access or the ability to TIG, I chose to bolt and use Loctite E-20NS adhesive.
That has been a couple of years now and the machine is still "glued" together!
Along the line, I have also done some milling and engraving of aluminum and brass! YMMV, but I am sold on it1

[JAZZCNC]

Wouldn't weld it together aluminium distorts something silly when welded and then it will be stressed so will start changing shape when these stress's release over time.!!. . . . Just bolt it together with adhesive like Loctite or epoxy.

[Greeny]

Have a look at Structural epoxy.
3m make a good range.
They bond Ali, Steel and other stuff.
check out this lo-tech, but impressive demo.
DP-420 3M EPOXY overlap shear test by Doctorbass PART 1 - YouTube

it aint cheap tho, surprisingly

Edit: There are now room temperature versions that are very nearly as strong.

[EddyCurrent]

That's the key word 'structural'

[FatFreddie]

As I understand it, surface prep is the key (pun unintended) to glueing aluminium - do exactly what the instructions that come with the glue say and if you can't (temperature constraints etc), find a different glue.

I would use enough bolts to put it on the skimpy side of ok without the glue and use the glue to provide a safety margin and extra rigidity. Doing it this way you might not need such fancy (expensive) glue.

I was thinking of using a medium strength loctite for the rail and linear bearing contact surfaces - one that would be separable if necessary but would stop any slippage.