What core bit size for what application?

[jimk280]

I'm thinking of buying a decent core bit kit. Most come in the following sizes and I understand the following size applications:

38mm - UNSURE?
42mm - basin waste pipe
52mm - bath & shower waste pipe
65mm - UNSURE?
117mm - Soil Pipe & Vents
127mm - Extractor Vents & some flues

Is this correct?

Also I would like to know what's the best size hole to drill through brick for copper 15 & 22mm bearing in mind that the copper will pe plastic sleeved also.

Cheers for any positive advice.

Jim

 

[newbie1]

well 15mm pipe drill 22mm
22mm pipe drill 28mm
and most of the kits are quite clever that they give you not quite enough for all mjobs forcing u to either drill bigger than you want or needing to buy a couple of xtra ones

 

[jimk280]

thanks newbie, appreciated.

 

[newbie1]

i think makita do a reasonable kit..the more expensive ones last longer but you pay a premium prob about 250.00 for a basic kit
as allways its not just the core bit its the drill driving it
if you can afford it get a dedicated core drill marcrist is a good make but again not cheap at about 400.00
is anything ever cheap in this game

 

[Bob Croft]

Another point to consider is the materials you typically drill. Where I live there are a lot of stone buildings. core drills do not like limestone and Chirt but easily drill gritstone, sandstone etc. I think virtually all core drills are OK when new but the cheaper ones wear more quickly dependant on the material you are drilling. If it is mainly softer stone brick or blocks then the cheaper cores may be worth considering.
I tend to buy the better ones (117) for drilling flue holes.
Another tip - if I have to drill a wall of very hard material and I can figure the hole position from the outside I core drill part way to get a neat hole. Then a drill a circle of smaller holes and chisel the rest out through the rest of the wall using a hammer drill with rotation off.

 

[oldplumber]

agree with u there. note that diamond core drills work best at high speed and an sds wont supply u with this. however i have used sds drills fm screw fix titans etc and the clutch goes within 6 months resulting in a return. screw fix are good at replacements and if u return the replacement, dont quote the original invoice but use the delivery note on the second and they dont always check back to the original invoice so u may get a replacement again outside the guarantee period.