Core Drilling

Does your cheap drill have a clutch? If not be careful! The cores bits can bind to a stop v. quickly and then the drill will spin you! (Broken wrists can be a problem.)

When coring don't try to be too quick: push for a bit, then pull back so that the dust can clear from the cutting bits.

125mm hole? This very w/e I've pulled my hair out and cursed manufacturers of odd sized kit.

If your pipe, or whatever it is you want to put in the hole, is 125mm then you'll need a bigger core bit.

I had 125mm flexible ducting, which needs a 140mm core bit to be used. But this size is not available for hire or sale anywhere near me!

If you've got a smooth pipe exactly 125mm external diameter, you might get away with a 127mm core bit.

good luck!

 

Hi John

Yoho + Don't try to do this off a ladder or steps... make sure to keep the drill in one plane as you draw it in and out. drill a pilot hole right through same diameter as the core drill pilot bit, then drill from both sides.

Personally, for 1 of jobs I'd hire the kit...but as you have it anyway...

 

John

I drilled a 110mm hole, 500 mm deep through granite (wall of a Welsh cottage for a new WC soil pipe). I have a Dewalt drill with clutch (essential) and initially used a TCT core bit. This was heavy going so I hired a diamond bit. I have to say honestly that there was not a great deal of difference in cutting efficiency/frequency of snatches etc. between the two! I didn't use hammer action. A complication for me was that the hole had to be sloping at 5 degrees from the horizontal. My only addition to the words of wisdom from the others is: take your time and work slowly - give the bit at least 2 minutes cool down time for every 1 minute use- I would not recommend plunging in water.

Hope it goes well

Peter

 

john.

i think i would be inclined to drill from the outside if this is possible. this will reduce the likelyhood of the render breaking off.
if you do have to go from the inside, then when you have broke through make sure you remove the loose render, therefore not leaving holes and gaps for frost to get in.

dj.

 

If you are going to use diamond core, coring can take place from either face of the wall and you do not get breakout when core exits other side. You do NOT use hammer action on the core.

 

Hi,

Just done this for the first time myself and it's pretty easy. Drill your pilot a size up from the guide in the core. Most hire shops throw in a drill with the core hire, I would go for that rather than a cheapo SDS. Since you must not use the hammer action, you are relying on the torque of the drill, and on a cheap drill this is likely to be poor - also there is the risk of it jamming and without a clutch stop that is at the least painful.

I was recommended to do it from the outside in - that way if there is any breakout, it's far easier to patch up the inside than the out.

Tango

 

Tangoman why should there be any breakout? Diamond matrix cuts the wall thus does not impact on it. When the core exits the other side, it comes out nice and easy. Even if the wall surface is weak, there is little chance of a breakout. Core has to start from the inside as that is where the hole will be centered. Starting from the outside will not gurantee exit at a precise point. Also what do you do when you are three floors up- I hate working off ladders. Does make a mess though (from dust) but then I use industrial vacuum toi keep the area dust free.

 

Hi dp,

you are right - diamond cores should not cause breakout - and certainly if it is difficult for one reason or another to work from outside, then yes.

I was simply recommended by an experienced plumber to drill from outside in whenever possible.

Without personal experience of things going wrong when drilled from inside I cannot really add anything to this.

If you have happily been going inside out for years without a problem, then I withdraw my point!

Tango

 

Hi John,

Did you use your cheapo SDS drill to do the job. I would like to know as I have one also and I will be looking to do a similar job for a sink waste shortly.

Ta,

DWD

 

Thanks John,

I have used the chisel action on mine to take tiles off and that was great and I keep looking to find things to do with it now. At the price I got it, I think it was £28, it really is a throw away so every job is a bonus now as it has paid for itself in labour saving already.

Good to know it did the job for you on the core drilling.

DWD

 

what make/ model no. was it please.

think i'll tell the missus that i need one.
ta.

dj.

 

Hi DJ,

Screwfix do the same one that I have badged up as a Ferm.

http://www.screwfix.com/app/sfd/cat/pro.jsp?ts=60542&id=94802

At £35 it is worth it as it comes with a three year guarantee as well. I did not see any of the drills I bought in my local B&Q when I had a quick look the other day but it is worth having a look before you order.

PS - Buy something else from Screwfix to avoid the P&P charge, the drill set perhaps?

DWD

 

Sorry for the absence. Yes that drill from argos is still going strong. I must have done at least 10 more various sized cores with it. If you are doing larger cores it works best at a lower speed otherwise the clutch tends to slip.

Avoid 620watt drills as they are a waste of time for core drilling. You need the 1050watt jobbies.

If the drill stops turning for cores it'll no doubt still be good for chiselling. Then back to argos for another.

Martyn