In article , "AlexW"
says...
wrote:
Hi,

I'm about to create a new window opening with a 900mm lintel into a
cavity wall.

Rather than start banging away I'm looking to use the 10mm mortar rake
bits from screwfix attached to a grinder to remove the top layer of
bricks and install the lintel first.

To make the cuts on the internal wall I'm going to use a 9 inch grinder
with diamond blade.

For the exterior brick work I'm looking to make it good by cutting half
bricks and mortaring them in the alternate courses.
That's presuming the the mortar comes cleanly off the full length
bricks and the courses are pretty regimental in the first place. An
alternative was to cut with a bricksaw and make good with a render coat
but not sure how to finish the render coat neatly around the opening
without some kind of frame..

Anyone got any other suggestions or advice I should take on board?

I really am no expert here (Caveat DIYer)...

Why remove the single course of bricks first? Sure you'll have a nice
lintel shape aperture if it does /not/ collapse. But even a single
course removed will mean its unsupported above - may as well take the
whole lot out.

But with only one course out it won't collapse very far :-)