What do you reckon then?

[davesparks]

Ok. Moving on. Searching for a flush fit or very low profile Matt/paintable white downlight that will fit through a 63mm diameter hole in ceiling. Options seem extremely limited or non existent from what I can see.
How does one expand an existing hole by a few mm. Does anyone produce a jig for a hole saw to keep it central or do I have to invent one?

Stack two holesaws together on the same arbor

 

[FatAlan]

Presumably that only works if the current diameter blade sits higher than the new, wider one?

 

[davesparks]

Presumably that only works if the current diameter blade sits higher than the new, wider one?

Yes, but they are normally all the same height, so the smaller one always sits higher.

 

[Pat H]

Ok. Moving on. Searching for a flush fit or very low profile Matt/paintable white downlight that will fit through a 63mm diameter hole in ceiling. Options seem extremely limited or non existent from what I can see.
How does one expand an existing hole by a few mm. Does anyone produce a jig for a hole saw to keep it central or do I have to invent one?

Here's what I do.
Cut a 63mm hole in a spare bit of ply or mdf. Take the round plug you just cut and screw it to a new piece of ply or mdf.
Take care to use 2 screws away from the edge of the round plug. Re drill the pilot hole from the round plug through the new mdf.
Now lift the new mdf and slide it till the round plug drops in the old 63mm ceiling hole. You will have a little movement so just centre it. now secure the mdf/ply sheet with a few temp screws. Then cut through the sheet and the ceiling with the new hole cutter.
That sounds more complex than it is....

 

[FatAlan]

Bit of digging around but Starrett do an Oops Hole Saw arbor.

View attachment 35117

 

[davesparks]

I hadn't realised such things existed, I've always just put a second holesaw onto the standard arbor

 

[FatAlan]

The interweb is a wonderful thing Dave if you know what thing you are looking for is called. I only found it by looking at Starrett hole saws on Amazon and taking a closer look at accessories.

View attachment 35119

 

[uksrevivor]

Stack two holesaws together on the same arbor

Well I be fecked that has to be the best bit of knowledge I have learnt in a long time and I will remember that for the rest of my career. I would never of thought of that and have struggled a few times before when I needed to open up a hole for a bigger diameter light fitting. Brilliant little trick.

 

[FatAlan]

All they need to invent now is a downlight with a decent connecting system that doesn't rely in those stupid incorporated screw down connect blocks! Still,I suppose thats part of the skill required to be a competent person!

 

[Leesparkykent]

All they need to invent now is a downlight with a decent connecting system that doesn't rely in those stupid incorporated screw down connect blocks! Still,I suppose thats part of the skill required to be a competent person!

push fit connector downlights - http://www.electriciansforums.co.uk/threads/push-fit-connector-downlights.113012/

 

[FatAlan]

The irony on this job is that the existing fittings are sat in 76mm holes so hole saw not needed! Still, on the plus saves a lot of work. Lesson - if dealing with proper customer rather than friend, do not rely on their measurements!