what sds Drill Size for 20mm conduit??

[brightsparkey]

I am using 20mm conduit as a sleeve. The wall it is going through is 600mm thick, so before I buy a pricey 1m long sds bit, I wanted to check what diameter to buy to make life easy.

Will a 20mm drill be too tight or should I go for 22mm ?? If I go 22 mm will the conduit be too loose and slide around?

The wall is breeze blocks if that makes any difference.

Many thanks for any advice,

Kevin.

 

[aesmith]

I'd probably go for 25mm, and aim to fill the space around the conduit either by pointing or maybe expanding foam. It depends how "crumbly" your blocks are.

 

[ekmdgrf]

I can't imagine you'll ever get a 20 to work but as previously stated masonry's a little unpredictable. Personally I'd get a 20, 22 and 25 and work my way up until it fits. I know you've pointed out they're not that cheap but judging by your userID, it sounds to be something you'd get a lot of use from.

 

[aesmith]

Could you rent?

 

[brightsparkey]

thanks for the help. USID might be misleading

I normally work on smaller more complicated things electrical/electronic...

I'd really like to buy only one 1m long bit at circa £30 - I've always managed up 'till now with my 450mm 'real mans' drill...

 

[bernardgreen]

My cottage has has stone walls more than 2 foot thick

I bought this 16 mm one metre long bit to make pilot holes

http://www.wickes.co.uk/invt/195594

and then working from both sides enlarged the holes with shorter bits

 

[ekmdgrf]

I've seen some el cheapo ones online for around £15. It'll probably self destruct after a couple of uses but if it's for a single job, who cares?

 

[brightsparkey]

Nice idea Bernardgreen, but unfortunately I only have access from one side.

I had a look and £15 ones are available from screwfix - thanks for the hint. I can't imagine even cheap stuff having trouble with breeze.

I'll go for the 22mm then unless anyone knows that won't work.

Cheers,

Kevin.

 

[Lectrician]

22mm for me.

25mm is sloppy - I use this if I need to sink the female conduit adaptor into the wall a short way, if the conduit enters the accessory, trunk, etc from the rear. 22mm hole through the wall, and then the 25mm for an inch to widen the hole.

 

[brightsparkey]

Bought 22mm 1m drill - did job perfectly - 20mm conduit sheath is snug but slides easily enough to go through cavity and thick internal wall. '8

Job done ! Many thanks for the advice.

Kevin.