Using a multitool to cut chases in blockwork

[Andrew]

Are there any suitable attachments for cutting vertical slots in internal pastered blockwork for electrical conduit ?.

I once tried the 4.25 inch angle grinder option with a diamond disk but even after creating a 'dust proof' tent around the work area there was some leakage and in just seconds I couldn't see what I was doing !.

A diamond cutter for my Einhall multitool would be interesting (if such a thing existed) but it would have to be one that fits the Einhall fitting properly ??. The multi-fit ones that have slots rather than holes always seem to me to be mechanically suspect. Once the ring of pins on the tool itself become worn then presumably that's it, game over.

Andrew

[ARW]

You might be better off with a dust extraction kit for the angle grinder.

[nothanks]

A coated multi tool blade works well in plaster (and plasterboard) and gives a good channel without too much dust, but then a scutch chisel will be needed if you want to dig into the blockwork.

[alan_m]

I used these to chase back boxes and channels in thick old style plaster and medium hard bricks

If the OP wants diamond blades then these are also available

[nothanks]

I tried the first of those in my 30s dense blocks but 'twas no good. A scutch, masonry drill and/or SDS chisel do the job much faster and without much mess.

[Michael Chare]

I must remember that. Last time I wanted to cut a channel I used a diamond tipped angle grinder blade. It cut the neat sides of a channel but created an enormous amount of dust and I had to quickly leave th room after one cut.

[alan_m]

I used my multi-tool to cut the straight edges of the channel and around the perimeter of the box and scutch chisel for the inner bulk removal

[Dave Plowman (News]

Sadly, anything that cuts a channel out of brick etc quickly is going to create a lot of dust. I'm sure you could make something with efficient dust collection, but the bulk of the entire thing might not be convenient.

[Tim Lamb]

In message [e-mail]>, "Dave Plowman (News)" [e-mail]> writes

Reducing the disc speed helps as does a vacuum cleaner held by a second operator.

>

[Andrew]

Err, how (the former, not the latter) ?

[Tim Lamb]

I have 3 angle grinders. 2 x125mm and one 230mm. They all have variable speed control.

[Andrew]

Oh. Something else I need to get then. Mine is about 25+ years old. A green Bosch PWS 7-115 I think, with just an on/hang on tight/off switch

[alan_m]

I recently purchased an angle grinder and thought a variable speed model would come in handy UNTIL I saw the price difference between a fixed and variable speed model :)

[newshound]

I have five, not counting the dremels. None of the mains ones has speed control, although the big one has soft start. The Lidl cordless 125 is variable speed.

[Andrew]

Is that full speed down to zero as the battery runs out though ?. :-)

[Tim Lamb]

I have Makita GA9020, 9565 and a Bosch PWS 7-115 (which will take a

125mm thin disc:-) I now see the Bosch is fixed speed.

[Andy Burns]

Wait for a day where there's a strong wind in the right direction to let it in though e.g. front doors and windows, and out through the back windows of the room you need to cut the chase in ...

[John Rumm]

It's called a wall chaser, and the dust collection is remarkably effective, so long as you have them hooked up to a decent vacuum. (or a cyclonic pre-filter on a ordinary one)

[Mike Clarke]

Apparently the Metabo wall chaser with the triple disk and dust extractor is very good - if you have 800 quid to spare.

[John Rumm]

I have the sparky one which in use is ok. The handling is a bit cumbersome (it suffers a bit form basically being an angle grinder body

- it would be nice if it had another slimmer parallel handle with a trigger on it, but it does the job).

The breakout of the core when cutting the slot with two disks in IME trivial - you don't often need the SDS - just sticking the flat blade of a bolter into one cut and levering to the side is usually enough to pop out the fillet.

(you could probably fit more disks - its just a long arbour with disks and spacing rings and a nut on the end. You adjust the arrangement of spacers to set the spacing. You can also use it with just one disk. Turns out that is handy for stripping plasterboard from studs).

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There are loads of budget models out there now which I expect will do the job equally well.