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Which tool to shave 5mm off a brick.


epsilonGreedy

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I am refitting some OSB window blanks to keep the weather out and need to trim a few 100 irregular facing bricks on the cavity side that are currently preventing the wood blanks fitting closely. Before anyone questions the competence of my brickie the bumps on the inside are due to the English Bond courses (a heritage look) that required 1000's of bricks to be cut in half and then laid 90 degrees to a normal brick. At the window apertures these half bricks create a jagged edge on the cavity side.

 

When I finally get around to fitting wooden sash windows with a full brick reveal these cavity facing brick courses will need to be near flat but in the first instance for the OSB blanks fairly flat it good enough. The wooden blanks are only 35mm oversized each side hence I just need to chisel/grid back slices of brick 65mm high x 35mm wide x 5 to 10mm thick.

 

I think my options for this brick trimming job are a 4" grinder or a multitool with a special blade.

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For future reference if you have a load of cuts on reveals it is worth hiring a petrol masonry saw.  Ear defenders, goggles, waterproofs and you can just spend a couple of hours chopping a pallet of bricks in half.  Strangely satisfying.

 

Obvs this would be before the bricks are laid!

Edited by Mr Punter
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1 minute ago, Mr Punter said:

For future reference if you have a load of cuts on reveals it is worth hiring a petrol masonry saw.  Ear defenders, goggles, waterproofs and you can just spend a couple of hours chopping a pallet of bricks in half.  Strangely satisfying.

 

 

I offered to do this but my brickie declined saying it would be too complicated juggling another stack of specially measured window reveal half bricks.

 

He did trim some of the window openings by running his full size Sthil petrol saw vertically down the cavities of the finished windows but he could not reach the top bricks due to the blade diameter, also it was the end of the day, he was tired and I could see little errors creeping in as he tried to steer the blade. So I called it a day.

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2 minutes ago, Mr Punter said:

You could hire a diamond chain saw.  I would get a grown up to help.

 

 

Thinking ahead to the eventually sash frame fitting, I would prefer to take it slow and steady. When the sash windows go in I will need the jaggy brick face down to a smooth finish with less than a 2mm discrepancy or enough that the final external bead of sealant will cover.

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19 minutes ago, epsilonGreedy said:

 

Thinking ahead to the eventually sash frame fitting, I would prefer to take it slow and steady. When the sash windows go in I will need the jaggy brick face down to a smooth finish with less than a 2mm discrepancy or enough that the final external bead of sealant will cover.

 

2mm is a very small tolerance.  Is there not a trim you can use to cover the gap?

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19 minutes ago, joe90 said:

Those concrete grinding discs work very well (but loads of dust?).

 

Agreed. I've used both the diamond disc and cup types with a small grinder with great success on concrete (which is much harder than brick). I also shaped some brick slips to go over and around some flashings - the diamond disc went through them like butter. As you say, lots of dust, but a mask and eye protection should be used when doing this sort of thing anyway.

 

@epsilonGreedy, unless there's an access issue, I'd have thought this would be a lot faster and likely leave a cleaner finish than using a multi-tool, although admittedly I've never used a multi-tool for this specific purpose.   

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21 hours ago, jack said:

Agreed. I've used both the diamond disc and cup types with a small grinder with great success on concrete (which is much harder than brick). I also shaped some brick slips to go over and around some flashings - the diamond disc went through them like butter.

 

 

Just logging my noddy experiences here to benefit others later...

 

After a 24 hour delay searching for the grinder disk release pin spanner I ventured out to experiment with the 4" 1/2 240v angle grinder. The two disks supplied with the grinder were useless, the 6mm thick abrasive disk was slow work. The thin cutting disk went through one brick but half way through the second I realized the disk had lost 1/2" in diameter.

 

I am heading out to my nearest Screwfix to buy a proper masonry segmented cutting disk, this Erbauer https://www.screwfix.com/p/erbauer-masonry-stone-segmented-diamond-cutting-blade-115-x-22-2mm/4896v at £6 is nearly 3 times cheaper than https://www.screwfix.com/p/marcrist-multi-material-diamond-segmented-blade-115-x-22-2mm/15915

 

Think I need some thick leather gloves as well.

 

 

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4 minutes ago, epsilonGreedy said:

I am heading out to my nearest Screwfix to buy a proper masonry segmented cutting disk, this Erbauer https://www.screwfix.com/p/erbauer-masonry-stone-segmented-diamond-cutting-blade-115-x-22-2mm/4896v at £6 is nearly 3 times cheaper than https://www.screwfix.com/p/marcrist-multi-material-diamond-segmented-blade-115-x-22-2mm/15915

 

Think I need some thick leather gloves as well.

 

Yes, you need diamond blades. Ordinary grinding discs aren't suitable (might even be dangerous - I don't know). The ones you've posted look fine.

 

Report back how you find them.

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1 minute ago, Russell griffiths said:

Gloves not needed, unless your silly enough to put it on your hand. 

 

 

See my new gloves thread.

 

1 minute ago, Russell griffiths said:

What you do want are goggles and ear defenders. 

 

 

Pardon? Can you say that again more loudly.

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4 minutes ago, jack said:

Ordinary grinding discs aren't suitable (might even be dangerous - I don't know). The ones you've posted look fine.

 

 

Yes indeed I abandoned my first trial when I noticed the reduced ragged edge to the cutting disk.

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4 hours ago, jack said:

Yes, you need diamond blades. Ordinary grinding discs aren't suitable (might even be dangerous - I don't know). The ones you've posted look fine.

 

Report back how you find them.

 

I have tidied up my first window brick aperture, the new £6 Erbauer disk works like a dream, it slices through the irregular brick overhanging in the cavity like butter. I will keep the more expensive Marcrist disk in reserve for a more demanding future job. Getting right into the upper corner of the window opening next to the lintel is still not possible with the 4" grinder, that looks like a job for a multi tool.

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Technique Update:

 

I discovered today that by shining my line laser across the irregular brick finish it creates a heat map of the high points on the cavity side of the facing bricks. I started off with a spirit level and marked the high points with a pencil, now I keep the laser trained across the brickface I am smoothing back and skim the grinder over the high points picked out by the laser line.

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