Core drilling.

[robj20]

Fitting a bathroom extractor so need a hole for the 150mm vent.
I've done 52mm with my SDS before don't fancy going to 150+ with it.
So looked at getting it done professionally but they want £250+vat.
Looked at renting and that's still pretty expensive and a hassle so stitch drill it is.

My plan was to drill a series of say 8mm holes pretty close together, then follow up with something bigger so as to break the core free.

Any tips on keeping the holes level or is it a case of just tidying it up later with the SDS and a chisel bit.

 

[^woody^]

Just use a bigger core bit. In this instance, size does not matter.

 

[robj20]

Just use a bigger core bit. In this instance, size does not matter.

So just buy a decent 152mm core and take my time again.

 

[^woody^]

So just buy a decent 152mm core and take my time again.

All being equal then yes, there is not much difference between drilling a 52 and 150 core apart from 98mm.

But you may not want to be balancing on a ladder 2 storeys up drilling a core, or if costs are a factor and you already have a few normal brill bits then stitch drilling and making good may be preferable.

Just draw your outline of the hole and make sure you drill to the outside of it not inside, else you will be there all week chipping away to widen it.

Or just knock the bricks out with a chisel and make good if the outlet cover will mask the making good

 

[robj20]

All being equal then yes, there is not much difference between drilling a 52 and 150 core apart from 98mm.

But you may not want to be balancing on a ladder 2 storeys up drilling a core, or if costs are a factor and you already have a few normal brill bits then stitch drilling and making good may be preferable.

Just draw your outline of the hole and make sure you drill to the outside of it not inside, else you will be there all week chipping away to widen it.

Or just knock the bricks out with a chisel and make good if the outlet cover will mask the making good

I can do the drilling from in the loft it's boarded so easy access, it's a Makita SDS with a clutch.

Am I right in thinking it might be best to drill a 162mm hole for 150mm ducting?

Stitch selling tip a handy so basically as I know it would be impossible to drill all the holes nice and level soon to drill them all so on the outside it ends up larger. The vent cover will conceal anything.

 

[Tigercubrider]

I hired a core drill for a one off a few years ago and don't remember it being expensive.

 

[robj20]

I hired a core drill for a one off a few years ago and don't remember it being expensive.

Looks to be about £40 for the drill, then bit on top of that, plus wear.

 

[Ian H]

They will charge per mm with a set minimum charge.

I'd buy a Mexco one from Toolstation.

 

[John D v2.0]

Am I right in thinking it might be best to drill a 162mm hole for 150mm ducting?

Yes round ducting is sized on internal diameter so it won't fit 152mm unless you drilled a wobbly enough hole.

 

[phatboy]

You may find your drill isn't up to the job - I lent a 5.5Kg SDS to a friend to drill a 105mm hole, and he burnt out the armature!

A dedicated core drill may be required at that size

 

[^woody^]

All this palarva, I'll come down and bang a roof vent on and be home in time for fish and chips tonight.