Best way to drill hole in floor flush against wall?

[perky416]

Hi guys.

The title may be a little misleading but essentially sums up what i need to do.

Please take a look at the picture attached. I need to drill or make a neat hole big enough to fit 20mm conduit in the slab below the rubber grommet, with the edge of the hole only a few mm away from the wall of my shed.

I have a 90 degree drill - the chuck makes the hole too far away from the wall unless i drill at an angle (trying to avoid).

I have a 90 degree chuck attachment - same issue as above.

I considered using a multi tool with a tile bit, but unsure if that will do it, and if so, if it will leave it neat.

How would you guys do it?
Is there a special tool in existence?

Thanks

 

[big-all]

drill at an angle till though then nibble below the surface with a rasp or file/chisel/buzzy toy narrow blade sandpaper to finish
keep in mind clips or other fixings may space off the wall

 

[perky416]

drill at an angle till though then rasp or file/chisel/buzzy toy narrow blade sandpaper to finish

Great idea, thanks.

 

[Notch7]

buy yourself a 600mm long drill bit, then it would be pretty close to 90 deg

 

[perky416]

buy yourself a 600mm long drill bit, then it would be pretty close to 90 deg

Another good idea, thanks. Im sure i have one lying around somewhere.

 

[opps]

I am confused... you want to drill downwards in to the paving slab?

If so, and you use a SDS bit, I would expect the slab to crack.

And how does drilling downwards help? Won't the water just run if through the hole?

Having read your other post, are you hoping to run armoured cable through the gromit and then down through the slab? That is a very sharp 90 degree return- I don't think it can be bent that much.

I believe that armoured cable is supposed to be buried 600mm deep, an electrician should be able to clarify that. If using armoured cable, It can be cleated/clamped above ground level.

I may be wrong, but if you can provide more information, someone should be able to advise you.

 

[perky416]

Yes i want to drill down through the slab. I will start off with a small diameter drill without hammer action and gradually work my way up to 20mm. Its been done before. If it breaks because it is so close to the edge i will simply re-concrete.

Drilling downward means i can run conduit down from the junction box straight into the ground.

As per my other post, and this one, i plan on using conduit to contain the cable, im not using SWA for the sake of 40cm travel.

 

[opps]

Yes i want to drill down through the slab. I will start off with a small diameter drill without hammer action and gradually work my way up to 20mm. Its been done before. If it breaks because it is so close to the edge i will simply re-concrete.

Drilling downward means i can run conduit down from the junction box straight into the ground.

As per my other post, and this one, i plan on using conduit to contain the cable, im not using SWA for the sake of 40cm travel.

So you plan to run the conduit just under the ground level? I don't think that is permitted. I might be wrong though...

Won't the conduit just fill up with water?

Can you not run any conduit above surface level? If nothing else, it means that it is accessible if anything goes wrong in the future.

 

[perky416]

You can do it, dw i have it covered, this isnt my issue. I dont want it surface level to prevent damage.

 

[big-all]

as an aside for cutting round holes up to the edge in wood i use a hex spade bit and my bosch 12v drill with changable heads with offset drive you can get somwhere between 12 and 15mm hole vertical with the overhang off blade from the shaft off the spade the same as the angle adapter to wall
random link

Bosch GSR 12V-35 FC Professional FlexiClick Drill Driver With 4 x Chucks L-Boxx | eBay

The GSR 12V-35 FC Professional cordless drill driver with brushless motor is the most versatile tool for any job in the 12V category. 1 x GSR 12V-35 FC Drill Driver. 1 x Drill Chuck Adapter GFA 12-B 1 600 A00 F5H.

www.ebay.co.uk

 

[thomp1983]

If you say your willing to re concrete any damage then I'd stitch drill across the concrete take a small section out, get the conduit in place and finished as you want then concrete it all in place nans make good the surface

 

[perky416]

I did it using the long drill bit method. I found i had 4x 400mm sds bits in my drawer.
I did the initial hole 8mm the stepped it up to 16mm, 20mm and finished off at 22mm.

This was a lot harder to drill through without hammer action than i have experienced in the past. I did it with hammer action, on a slow drill speed with very light pressure to avoid it breaking.

If the angle isnt vertical enough or its too close to the shed ill file it out.

 

[Notch7]

I hate to mention it but the paving slab base should be slightly smaller than the shed, not bigger

the sides of the shed should protrude beyond the base so any water runs down past the base

 

[perky416]

I hate to mention it but the paving slab base should be slightly smaller than the shed, not bigger

the sides of the shed should protrude beyond the base so any water runs down past the base

Not according to the shed manufacturers guidance. The base is built to the size as per their instructions in the assembly manual.

 

[opps]

as an aside for cutting round holes up to the edge in wood i use a hex spade bit and my bosch 12v drill with changable heads with offset drive you can get somwhere between 12 and 15mm hole vertical with the overhang off blade from the shaft off the spade the same as the angle adapter to wall
random link

Bosch GSR 12V-35 FC Professional FlexiClick Drill Driver With 4 x Chucks L-Boxx | eBay

The GSR 12V-35 FC Professional cordless drill driver with brushless motor is the most versatile tool for any job in the 12V category. 1 x GSR 12V-35 FC Drill Driver. 1 x Drill Chuck Adapter GFA 12-B 1 600 A00 F5H.

www.ebay.co.uk

I have the Metabo drills that offer the same functionality. I first saw it with the 15.6v Festool drill about 18(?) years ago. I have to admit that I never used the offset Festool attachment. I did use the 90 degree attachment from time to time though. Unfortunately the batteries on the drill are now useless and I refuse to pay £90 to rebuild each NiMH battery,

I almost purchased the one that you have but got a better deal on the 12v Metabo version- it only came with the standard removable chuck but for £200, I got an the (brushless) drill plus a 12v (brushless) impact driver and 2 batteries and a charger. The right angle attachment, I got elsewhere for about £25 incl delivery (a steal).

Roll on a year, I needed a cordless that had a RPM of in excess of 2000 to use with my Souber DBB door lock mortiser. I spent £300 on a 18v Metabo that also has the interchangeable chuck.

From memory, only Festool, Bosch, Metabo and Milwaukee sell drills with interchangeable chucks. Not sure if any of them, other than Metabo sell them in 12v and 18v versions.

In the past, I had tried using the pants angle attachments that will work with any drill. IMO they are rubbish. Not only do you have to apply downward pressure on the drill, you also have to hold the handle of the attachment to stop it spinning around.

I haven't purchased the offset attachment for either of them though. If I had to deal with knock down fittings, I would buy one in an instant. In the meantime, when possible, I will use longer drill bits.