mounting bracket

[Derbyboy]

What screw should I use to attach one 45 rule to another 45 rule?

The attachment should be done by screwing through rule 1 into the end grain of rule 2. Normally, one might use a joist hanger for such attachments, but I want to screw. The rules together form a T.

Is it preferable to use a longer screw like 6x140 instead of a 6x90 even though the unthreaded part will go far into the connecting rule?

(sorry if my description is somewhat confusing, but it is a pedagogical challenge to explain)

Best regards

 

[Evamag]

Essve construction screws.

https://www.essve.com/sv/produkter/...sskruv/et-t/konstruktionsskruv-et-t-corrseal/

 

[patrikd84]

Angle brackets are available otherwise. And everything depends on what the joint will be loaded with.

If you don't want to use brackets, I would suggest screwing at an angle (2 screws) and adjusting the screw length accordingly.

 

[Tomture61]

Never a great idea to screw/nail into end grain.
The above suggestion sounds okay.
If you own a router or Japanese saw + chisel, make a dovetail that you screw-glue.

 

[Oldboy]

Is it preferable to use a longer screw like 6x140 instead of a 6x90 even though the unthreaded part will go far into the connecting beam.

Yes.
Long and thick screw for the best hold and strength.

Otherwise, nails are good, like 150 mm.