core drilling 162mm for kitchen extractor vent

[NHW]

instructions on my vent - eiQVENTKIT150COWL - Say that a 162mm minimum hole size is required for the kitchen vent.

I already have a trusty Titan TTB631SDS which has a safety clutch, but I am told that it shouldn't 'really' be used for doing core drilling, and that 162mm is quite a large size which should be used with a specific type of core drill - Hilti 110's / Makita DHR242Z etc. Which for drilling 1 hole I would not see the return in buying outright, renting I think is around £90 a day approx.

Not many places also have a core bit which is larger than 150mm, so the 162mm core bit I am just thinking to go and buy anyways.

https://www.toolstation.com/mexco-premium-slotted-dry-diamond-core-drill-bit/p30062

I'm just wondering if its just moreso a suggestion that you cant use the Titan for this type of job and that if you basically just take your time and go slow it would be alright. Its just for a normal residential property so brickwork, blockwork and a cavity. Thank you for any advice in advance

 

[Murdochcat]

I had a 6” core drill and very rarely used it. Having said that when I needed it I had it in my garage

 

[thomp1983]

The titan will do it, to make it easier on the drill I'd start the core and once the core bit is about 15-20mm into the wall remove the core and use an sds masonry bit to stitch drill all the way round the groove the core has created then use the core drill again to finish the hole.

 

[JohnD]

You could hire one, but it will be very heavy, and risky if you are on steps or a ladder.

Your drill will probably go through the blockwork OK, but for the outer leaf it might be neater to take out a few bricks, and rebuilt round the duct. Remember to tilt it so any rain or condensation runs outside.

 

[opps]

I had a cheapo Titan, about 1500w. I used it to drill up to 150mm. Both times I was going through solid 9 inch walls. I started with a SDS drill bit the same size as the pin in the core but long enough to go all the the way through the wall. Although it is not listed as having a safety clutch, I drilled slowly and regularly moved the core back and forth to remove the dust whilst working. Not ideal, but it worked. It did snag a couple of times but the power died immediately. I suspect that I didn't end up with a damaged wrist because the core was so large (preventing the drill continuing). The only time I hurt my wrist was using a 12mm bit which snagged against a metal gate fitting on a brick post. That hurt. Never experienced that when using my smaller SDS drills.

I am not telling you to use your Titan, I am simply saying that I have and lived to tell the tale.

Oh, and I drilled from both sides to prevent breakout. An advantage of using a long SDS drill bit.

 

[opps]

As an aside...

My core drill arbor has a straight centre bit. Diamond core bits are generally intended to be used with hammer action turned off. Why are so many arbors sold with a SDS drill bit in the center?

 

[Justin Passing]

As an aside...

My core drill arbor has a straight centre bit. Diamond core bits are generally intended to be used with hammer action turned off. Why are so many arbors sold with a SDS drill bit in the center?

I only ever drilled the centre hole first, then put a plain rod the same size as the bit I'd used, which fixed in the arbor using a tapered end.
I thought they were all like that. Yes you can use a heavy sds drill for its clutch, if you don't have a bespoke machine.
Yes to stitch drilling, try from both sides. they usually drift in a thick wall.
Unless you have a bank vault robber's rig, it can be quite hard work for the larger sizes.

If it makes a funny noise, you may be going through rebar. Yes you can if you're careful enough, without taking the segments off the core drill.

 

[NHW]

The titan will do it, to make it easier on the drill I'd start the core and once the core bit is about 15-20mm into the wall remove the core and use an sds masonry bit to stitch drill all the way round the groove the core has created then use the core drill again to finish the hole.

ahhhhh ok I get the methodology behind this, so basically pull out once 12-20mm in and then try break up with a masonry bit on hammer mode? am I aiming to get the rest of the way through to the cavity or just basically chip away until im nearly there and then re-finish with the core. Only thinking because i wasnt sure how clean I could stitch drill so that there arent any sharp edges left that the vent will/could get snagged on lol

I had a cheapo Titan, about 1500w. I used it to drill up to 150mm. Both times I was going through solid 9 inch walls. I started with a SDS drill bit the same size as the pin in the core but long enough to go all the the way through the wall. Although it is not listed as having a safety clutch, I drilled slowly and regularly moved the core back and forth to remove the dust whilst working. Not ideal, but it worked. It did snag a couple of times but the power died immediately. I suspect that I didn't end up with a damaged wrist because the core was so large (preventing the drill continuing). The only time I hurt my wrist was using a 12mm bit which snagged against a metal gate fitting on a brick post. That hurt. Never experienced that when using my smaller SDS drills.

I am not telling you to use your Titan, I am simply saying that I have and lived to tell the tale.

Oh, and I drilled from both sides to prevent breakout. An advantage of using a long SDS drill bit.

the first part did you basically use that long sds drill bit in order to drill right through the wall first so that you would then know where to aim for from the outside? basically would be the same hole from the inside as there is on the outside so you then use that as the centering point for the core.

yes mine is the 1500w Titan that i've had for a while now and used it for anything and everything so far, it is listed on the spec sheet as having "Mechanical Safety Clutch" but I lost the instruction manual and when I've looked online at other people mentioning it apparently it says not for core-ing on the booklet lol BUT like yourself they have managed to do it, albeit its a proper heavy unit in itself.

so the key would be to move slowly and obviously take small breaks even if its to just let the dust move around in order to get out. I would love to drill from both sides tbh but the inside of the house is finished and I know how much dust it can create. When getting to the final bricks (inner leaf) would it make sense to basically draw the perimeter of the finished core, then just stencil the hole and do multiple drill-holes around it with a normal hammer drill so that when the core comes from the other side it would hopefully be easier and create less mess?

Thanks for all your replies btw

 

[martygturner]

Personally I would not bother with a core drill.. just drill the circle line + 10% and smash out the core with a lump hammer the fit a collar

 

[Deluks]

pull out once 12-20mm in and then try break up with a masonry bit on hammer mode?

That works, if you have another drill you can attack the circle you've just cut, diagonally from outside to in.
The point is really just to reduce friction on the diamond bit as it goes in.
Keep vaccing out the dust for the same reason.
I can drill a 125mm hole in a 9" wall with a lowly 2kg SDS drill, takes about an hour, it's important not to be in a hurry, and observe mechanical sympathy for both drill and bit.

Will be quicker for you if the blockwork is lightweight/breeze.

 

[johnny2007]

The titan will do it, to make it easier on the drill I'd start the core and once the core bit is about 15-20mm into the wall remove the core and use an sds masonry bit to stitch drill all the way round the groove the core has created then use the core drill again to finish the hole.

I do this with hard bricks.
Some bricks though are very easy to core.
Most difficult part of the job is to keep the drill steady otherwise it jams and clutch kicks in.