Aluminium adhesive

[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.

[Danielroyal25]

Thanks for the input guys. I will go with the bolt & adhesive option then. Will go for a loctite structural epoxy, grade tbc.
I'm guessing the entire surface won't have to be coated only dabs equally spaced across the area?
With the fixings to bolt the ballscrew bearings on etc do people tend to loctite these in due to vibration or use spring washers or nothing at all

[JAZZCNC]

With the fixings to bolt the ballscrew bearings on etc do people tend to loctite these in due to vibration or use spring washers or nothing at all

Spring washers are my preferred choice.

[compositepro]

I do a lot of bonding things together ,think things that pull lots of G's

Bonding would be a great way to go with some rivets in there also

Remember aluminium is filthy to glue together ,the same oxide layer that likes to form to stop it corroding regardless you need to etch it and prep and for high end applications actually convert the surface to a different layer substrate, clean it and degrease it scrupulously if you do not have access to acid etch or anodic treatments ,the strongest adhesive is useless if it cannot get purchase on the alloy

Dabs of glue? bonding rlys on film thickness ,called a bondline dabbing blobs will cause unevenness you need a uniform bed of adhesive ,dont think of it as liquid nails unless your doing your skirting boards

Also aluminium rivets act as mechanical fuses should your glue decide to divorce itself from the aluminium will not allow you to apply forces that will distort the joint