100mm vent pipe hole cutting

[Bob Watkinson]

Anyone any tips on the best method of cutting the hole to the outside for the vent on my cooker hood? Is it a case of drilling multiple holes through the bricks and then cold chiselling out?

[Rob Convery]

Thats exactly how I did mine. Only took around 1/2 hours to do the complete job. Ony purchases were a long drill bit and a wide chissle. Drill one in the middle the whole way through and then use that to mark circles on either side of the wall. Much easier to drill do one side at a drim that try and do it all in one

[Andy]

You can get 100mm core dills for a neat job, try Machine Mart or Screwfix etc.

Myself, being a cheapy, and having only a single skin brick wall to go through, just drilled lots of holes in a circle then chiselled out.

To be exact, my technique was to mark out a ring of holes seperated by just over one drill diameter. Then, using a smaller pilot drill I drilled these out ( be super careful about alignment, else the holes will merge, so keep the drill perfectly at right angles to the wall ).

When you have a ring of pilot holes, use a larger drill of a diameter that will just about join the holes up, and then drill out the pilot holes, every second one at first, then the remainder.

It may seem a lot of palaver, but if done with care it will stop one hole wandering into another adjacent hole as you are drilling, which completely stuffs you. The pilot holes help keep the larger drill on target as they go through.

If you drill well-aligned holes, you will not have very much material left to chisel out at all.

Andy.

[s--p--o--n--i--x]

You could buy/hire a 100mm core bit and SDS drill.

sponix

[Malcolm Race]

Hire a diamond core bit and a suitable drill (if you haven't a 1000W drill with a clutch - very important) I used a 650W SDS drill without hammer & it was just adequate

Malcolm

[darren_forward]

Malcolm how much did the hire cost you.

Darren

[JoeJoe]

6" core drill + powerful sds drill + 110v transformer was £39 for the day around 6 months ago. 4" is probably a little cheaper.

PS: HSS were found to be the most expensive around - try a local hire place instead.

[JoeJoe]

Just remembered, ~£3 of it was the core drill insurance.

[Clive Dive]

Be careful of rip off 'wear charges' We found it cheaper to buy a coredrill for 4 holes

[Beer Doctor]

chisel.

When I did our extract fan hole, I hired a diamond cutter and the heavy duty drill to make easy work of the job. Or so I thought! It took too much effort to hold the weight of the drill and to exert the force needed that it was a great deal harder.

Make your choice and let us know how you got on.

Cheers Brian

[Bob Watkinson]

Many thanks for all the advice guys. Haven't done it yet but have the job on my 'to do' list. Or should I say Mrs W has it on my list ;-)