Turns out some new walls lights I have are tapered and I will have to enlarge existing the holes in the brick wall to get them in. Currently the holes are about 70mm diameter and need to be about 1 or 2mm larger over half their depth. Looking for suggestions on the best way to do this. I have eight to do.

 

Screwfix have a 78mm core drill and suppose I could make a wooden plug with a 10mm hole in the middle to guide it. Would probably jam a lot. Any other suggestions?

 

I can't get the light fittings turned down because I don't think the wall thickness of the fitting is sufficient.

 

Edited July 23, 201610 yr by Temp

How deep do you need to ream them?

Probably only the outer 50-60mm or so needs to be enlarged.

 

 

I'm wondering if an internal grinding wheel might work?

Can you get hold of a smaller diamond core drill ( beg / borrow ) and use it side on to ream the hole accordingly. ?

Yes looks like some experimenting needed.

May the sideways force be with you.  

You could do with a diamond grinding drum like this:

http://www.dk-holdings.co.uk/stone/vacuum.html

 

I'll have a dig around in the morning and see if I still have one laying around for you to borrow!

Thanks!

 

While I was googling for possible ideas I came across this site with what looks like very low prices on TCT core drills. Perhaps too low?

 

https://www.beal.org.uk/stock-clearance/core-shells.html

TCT may damage the face before cutting in. I'd only consider diamond for this job tbh. 

Frogeye - Thanks for the offer but I've now discovered several of the holes aren't deep enough either so I've invested in a core drill bit.