Wall Chasing

[wizer]

Hi Guys

I am chasing out the channels for my AV cables. I was using a mini angle grinder but it wasn't cutting deep enough. I set about chiselling it out but it's taking an age and my back has given out on me again. So I purchased a cheap 230mm angle grinder.

Question is: How can I limit the depth of cut? The wall is brick built but I have a feeling the bricks are on edge so I don't want to go too deep. The trunking is 29mm deep so it needs to be roughly 35mm I guess?

Was thinking about glueing some blocks of wood to the grinder, but the blade wears down quickly so it would make it useless.

Your thoughts appreciated.

 

[Jake]

A small (4.5 or 5 inch) grinder should do 35mm and is a lot more wieldy - get a diamond blade so the blade doesn't wear down (significantly) - the B&Q cheapos are less than a tenner for a pack, and are OK for occassional use.

You could screw wood battens to the walls to guide the grinder and limit the depth - this works well as the diamond doesn't like cutting the wood (too soft). I've done this on floor chases, where you don't need to phaff around with the screws, which might make it more of a bother. Not tried it with normal masonry disks, but it probably wouldn't work as well as they don't object to cutting wood quite as much.

Big grinders are aggressive and awkward beasts, and they have a massive kick to them if they catch. Not something I like to use except on the floor, where you just have to control the machine, rather than having to support its weight in the cut as well.

Edit: what I actually do in this situation (unless it is just a couple or so short chases) is go to HSS and hire one of their Hilti chasers. Costs £70 odd quid but makes the job much simpler, with depth and width settings, cuts both sides of the chase at once, and is much less prone to wander around - less dust too.

 

[misterfish]

Wall chasing is not fun!

Using an angle grinder, especially a larger one is heavy and hard work and makes huge amounts of dust that seems to have the ability to get everywhere. When I tried this there was so much dust in the air that I couldn't see across the room.

I also was wearing the masonary cutting disks down very quickly, so any depth stop would have been rendeder useless. I quickly discovered that I needed to use a diamond blade which made a thinner cut and didn't wear away quickly.

But, to do the chasing we ended up using a dedicated chaser - sort of an angle grinder with 2 parallel diamond cutter discs that you could adjust the width and depth of cut. This also had a dust extract system (linked to a Henry vacuum cleaner unit which reduced the dust escape by (what seemed) 99%.

You can buy cheap chasers like this or expensive ones. We used a Makita (or should I say the builder used a Makita) with 125 mm diameter disks - this would cut to about 30mm deep and 30mm wide - it had adjustable depth setting like a hand held circular saw. We did look at the larger version with 230mm disks but it weighed a good 10kg and was difficult and awkward to use, but this would do wider and deeper cute.

The other thing is that you have to
chisel the chanel out after cutting the sides and we used an SDS drill with 1 inch chisel.

It obviously depends on how hard your bricks are. Our new extension has these foamed concrete blocks that are easy to work and cut, but the older part of the house has very hard bricks (almost like engineering bricks) and you had to take the disk cutter slowly otherwise it would grind to a halt.

All this is hard physical work and working at and above head height absolutely knackered my arms.

I wish you all the best - I recommend taking it slowly, especially if you have a bad back. I was limited in my capabilities as I was (and am still) recovering from a broken leg.

Of course, it depends how much channeling you need to do - our complete rewire needed a lot, your AV system will hopefully be much more resticted and you will be able to do it as and when you feel up to having another go.

Good luck

MisterFish

 

[Scrit]

I'll give you two further altrernatives - use a diamond-coated steel disc instead of the cloth-backed type. They retain their diameter and don't wear down. Or if you have an SDS with rotation stoip (hammer only) then Armeg do these beasties which really do work. They work well in blockwork, soft stone and red brick but won't touch engineering brick. They still generate a fair bit of dust, but less than the angle grinder I'd say.

Scrit

 

[RogerS]

I'll give you two further altrernatives - use a diamond-coated steel disc instead of the cloth-backed type. They retain their diameter and don't wear down. Or if you have an SDS with rotation stoip (hammer only) then Armeg do these beasties which really do work. They work well in blockwork, soft stone and red brick but won't touch engineering brick. They still generate a fair bit of dust, but less than the angle grinder I'd say.

Scrit

I second that. I used one on block work and it was like a hot knife through butter. Virtually zero dust.

Do not use an angle grinder unless you want to be eating brick dust in your cornflakes for the foreseeable future. I jest not.