diamond core drilling for vent - TIPS PLEASE

[glider2]

Hi,

I need to fit a 300mm long, 107 diameter max vent for a fan through a layer of tile and bricks, totaling 300mm thickness. I purchased a diamond core bit (diameter 107mm) with a 8mm guide bit and will hire a clutched drill for the job. I also purchased a 10mm X 300mm masonry bit to drill a pilot hole.

My questions:

1. the diamond core bit is dia 107 mm but so is the max outside dia of the
vent pipe. Will this be an issue? Should I drill wider or just finish off with a cold chisel if the pipe doesn't fit straight away?

2. the pilot bit is of 10mm diameter and the guide bit is a bit less at 8mm. Is this going to be a problem? Should I buy a smaller pilot bit to make sure my sure my end result is straight?

3. how do I get through the surface layer of tile? Do I need to do anything special like drill around the contour of where the diamond core will drill, say with a 5 mm bit for example? Or do I just go in with the the diamond core bit straight away after I've drilled the pilot hole? The entire hole will be contained within the surface of one tile, i.e. no drilling accross grout.

Any other tips?

Thank-you.

 

[gas4you]

I would use the same sized bit as your guide, especially as you are going into tile. You dont want the core bit moving around.

Just start off with the drill slowly until it has scored the tile enough to hold it in place, then increase the speed.

Once I've got about 1/2" into the wall I usually remove the guide bit.

You may find the duct very tight being the same size as the core bit, although it may gain a couple of mm in use through movement.

 

[Newboy]

You don't need to pilot through with a 10mm - let the 8mm guide bit do the job (once the core has started to cut you can remove the guide bit)

Keep the core level - if it start to go off line you won't be able to get it back.

It may be worth piloting the tile before you start - with a bit of luck the core get through without breaking the tile.

Clear the core at regular intervals

Make sure that you have a good grip before you start - don't try to core drill balancing on anything other than a flat level surface

Take your time and good luck