Cutting a 300mm circular hole vertically

[joesan]

I need to install a 30cm metal speaker grille/cover vertically into some plasterboard (sheetrock) above head height. The plasterboard has nothing behind it. It's supported elsewhere on some battens.

What's the best way to cut out the hole and also recess the edge a little so that the 5mm thick cover will sit flush with the plasterboard? It has to look very neat. I was thinking about using the Festool OF1010 and the tramel attachment to first cut a 5mm rebate at 300mm diameter, then a smaller hole of about 290mm diameter, so that it sits flush.

I think it would work but I'm a bit worried about using the trammel and router vertically and while up a ladder!

 

[Jim_in_PA]

Having a clean edge with a recess on plaster board/drywall is certainly going to be a feat...it's going to take a lot of manual dressing work on your part, regardless of how you cut the hole. If you really, really need things flush mounted, you may be better served by inserting a larger panel of a solid material into the plasterboard with the recess pre-cut and then dress out with compound to make the insert panel "disappear".

 

[Sanderxpander]

I second that. Way easier to fill out the plaster than to cut it perfectly without damaging anything.

 

[joesan]

Thanks guys. Thinking about it that probably makes sense. It’s just that I’m paranoid about getting it the same finish as it’s in a very minimal setting where every detail out of place will show.

 

[Michael Kellough]

Get a cheap little trim router to use with the trammel. The OF 1010, small as it is, is too big. Anchor the trammel with a screw instead of just a pin so you can hold the router with one hand and the vac hose with the other.

Might be able to partially disable one of the larger drilling vacuum jigs (Bosch) to fit over the trim router without adhering itself to the ceiling.

 

[Master Carpenter]

Cut a template using the trammel, then use 2 sided tape to hold that to the wall and cut from there with your preferred method.

 

[Jim_in_PA]

Thanks guys. Thinking about it that probably makes sense. It’s just that I’m paranoid about getting it the same finish as it’s in a very minimal setting where every detail out of place will show.

Very understandable. But plasterboard/drywall isn't very friendly to things like having a recessed edge like you want to flush mount the speaker. By putting in a panel made of material that's more amenable to that  machining and then blending in the surface with mud, (obviously some skill required there) you'll get what you want and need to mount those speakers both securely and flush mounted.