Cutting a larger light hole over exisitng one

[jamesdean1986]

I'm changing some down lights from low voltage to 240v.

Ive got to double check, but I think the new ones require a larger diameter hole and I'm a little unsure of what the best method to make the hole bigger. I would prefer not to bodge the hole.

If I cant get anything above the ceiling to centre a hole saw, what other methods would people suggest?

Has anyone seen jig for this?

 

[Diyisfun]

I used a pad saw, after drawing round the old hole first.

 

[DetlefSchmitz]

Glue a strip of wood across the hole?

 

[jamesdean1986]

Thanks.
I had considered pre-drillin the hole in a piece of wood and then holding that in place to guide.

 

[aesmith]

If I cant get anything above the ceiling to centre a hole saw, what other methods would people suggest

Cut a disc the same size as the existing hole, with a hole in the centre for the hole saw pilot drill. This should allow you to keep the hole saw centred long enough to get the new outline defined.

What are the sizes? Existing hole, new hole.

 

[Adam_151]

If you start slow and put go in at an angle putting the edge of the holesaw against the edge of the existing hole to get a start then its not too difficult

Or if you have an hole saw the same size as existing, see if you can get it on the same arbour as a guide

 

[Taylortwocities]

Or if you have an hole saw the same size as existing, see if you can get it on the same arbour as a guide

Yes! I have done that a few times. Put new size holesaw on the arbor.
Then get a holesaw the same size as the existing hole and put that on the arbor too (it works even better if you can pop on a spacing washer or two).

Then you can drill away. I usually use a combi drill and set the chuck adjustment on about half (like you were using a screwdriver bit). Then you'll save your wrist if the blade catches.

 

[jamesdean1986]

Thanks everyone, some great responses.

The new lights are 66mm diameter but got to double check the old ones.