Angle grinder advice needed.

[chainsaw_masochist]

I need to create a couple of channels in a concrete portion of a bathroom floor in order to run two lengths of 15mm copper pipe to a bidet that I am installing. Thought I could do this creating a series of holes with a masonry drill bit and knocking out with a mallet and cold chisel. No chance: the masonry is far too hard. So I shall probably need to get an angle grinder. The dimensions are length: 150mm; width: 30mm; depth: 30mm.

Haven’t used one before so wonder what the sages on the site recommend? Can I get away with 115mm, or should I go bigger? Any manufacturer’s that stand out? Also what material disc should I consider?

Thanks in advance for any advice.

 

[Deluks]

I need to create a couple of channels in a concrete portion of a bathroom floor in order to run two lengths of 15mm copper pipe to a bidet that I am installing. Thought I could do this creating a series of holes with a masonry drill bit and knocking out with a mallet and cold chisel. No chance: the masonry is far too hard. So I shall probably need to get an angle grinder. The dimensions are length: 150mm; width: 30mm; depth: 30mm.

Haven’t used one before so wonder what the sages on the site recommend? Can I get away with 115mm, or should I go bigger? Any manufacturer’s that stand out? Also what material disc should I consider?

Thanks in advance for any advice.

What drill were you using, and did it have hammer action? You will need an sds or very good impact drill to make any holes in concrete.

Grinders:
If you haven't used one before then get a smaller one, also a diamond disc to make it useful. They come in handy for loads of jobs so you're sure to find other uses for it in the future.


I have a 900w black and decker, which you can now get online for about £20 and is a lot better than the name would imply.

Screwfix do a 5" makita with free diamond disc for about £50.

Having said all that you probably wont get full depth of cut without a full sized grinder so you could hire a bigger one if you're feeling brave but take all safety precautions.


..or, you might be better off chasing out with an sds hammer drill.

 

[chainsaw_masochist]

Hi there, Deluks. The drill I was using was merely a Bosch 650w with hammer action and an assortment of Bosch and Makita bits. Unfortunately this is not an SDS model; it’s really a DIY item. I only used it because I was pretty sure that the Makita battery drill I normally use would drain down pretty quickly given the material. It was then that I thought a grinder would be the solution.

Since making the original post a mate of mine has offered to lend me a fairly basic Wickes 125mm grinder. He uses it regularly and says it is very reliable. My idea was to go and get one similar to this but more importantly he has suggested that I take a trip to his place for a lesson in the rudiments of grinding (aw missus!). As he has done an H&E course in using this type of tool I thought it might wise ‘cos I don’t really fancy an impromptu trip to the A&E.

The point you make about perhaps not getting a full cut is understood. I may end up having to hire an SDS drill as well in anycase. Thanks for your help.

 

[JamesHughes]

Just remember that 9" angle grinders are scary old things. I always use my 115mm one in preference (got a couple, even the cheap as chips screwfix one with diamond blade is fine)- the big ones are heavy unwieldy and dangerous things!! As said before lots of safety gear advised.

 

[JohnD]

OOI, is this a concrete ground floor, or an upper floor e.g. a flat?

I am wondering what will happen to the strength of a concrete floor if you cut a channel in it.

 

[wanabechippie]

I have both a big and small angle grinder for various tasks. Had to cut a number of slots in a concrete floor a few weeks back. Used the larger one with a diamond disk - no probs at all.

One thing tho: grinded concrete makes a hell of a lot of dust! After 20seconds, the room I was grinding in was completely whited-out! Water on the floor didn't seem to help at all. Not sure what else I could do to stop it.

 

[oilman]

Hire a wall chaser. They have twin diamond blades, and you will need a dust collector for it unless you like weeks of cleaning.

 

[big-all]

OOI, is this a concrete ground floor, or an upper floor e.g. a flat?

I am wondering what will happen to the strength of a concrete floor if you cut a channel in it.

exactly my thoughts

also what about other services in the concrete like electric 'gas ' heating 'water'
and even underfloor heating

 

[chainsaw_masochist]

James Hughes: It is a 115mm that I have borrowed. Wouldn’t fancy using a 9 incher at all. Got plenty of safety gear, thanks.

JohnD & Big All: It is mainly a wooden floor but with section that is concrete. I understand from the owner that this bathroom was once a sitting room and that there was originally a fireplace and it is this area that is now concreted and occupying about six square feet of the floor. The channels that I require to create seem a very small portion of this area. So I would not anticipate my work weakening the floor in any way. I am also using an electric pipe detector which has picked up no sign of anything yet. Will tread cautiously though.

Wanabechippie: In order to keep dust to a minimum I was planning to use the large box that the bidet came in around the object area which should hopefully retain most of the dust. I would make a cutout at one end for me to work through with the grinder.

Oilman : Would a wall chaser be preferable to a grinder for my proposed channels? As said 150mm x 30mm x 30mm.