Advice needed regarding how to cut engineering bricks.

[plasticpigeon]

I have got invvolved with my local village in bloom. I'm building a circular retaining wall for a flower bed, 2ft high 10 ft diameter so nothing too grand. We are getting subsidised bricks from E H Smith, the local merchants. They suggested some oldy worldy handmade looking faux aged bricks for the facing which is fine, and I just asked for the cheapest bricks for the foundations and the inner skin. It turned out the cheapest bricks were red perforated engineering bricks. No problem I thought. However I can't cut them. The facing bricks cut easily with a cheap diamond wheel on a 4.5" grinder, but the engineering bricks don't cut well at all. They are super hard and although I can cut them eventually, the wheel gets very hot and glows and the brick seems to melt rather than cut and there is very little dust produced. I've only cut old bricks before and even blues are easier than this!!! Can anyone suggest what I need to cut them please. I would prefer a disk that I could use on my 4.5" grinder rather than getting a wet cutting tool as I have a lot to cut and will be doing it a few hours a week, so hiring a tool is not very practical, otherwise I may have to get some different bricks!

 

[a twig]

Bolster and big hammer? Worked for mine when building a small retaining wall for a trench

 

[Toby Newell]

I presume you mean the bright red ones in the middle.

They will tend to split if you attempt to dress them with a brick hammer, you will need a more expensive diamond wheel if you can't hire a Makita cutter with water feed (or helper with water bottle and steady hand)

Alternatively you could use LBC B grade commons which should be easier to cut either by hammer or disc and only cost 70p ea cf. 45p for red engineered and £1.50+ for LBC A grade reds.

 

[Flyfisher]

Bolster and big hammer? Worked for mine when building a small retaining wall for a trench

Agreed. I've always though that's what the holes were for, to make splitting the bricks easier. Since they won't be visible in the final construction a nice clean cut isn't really necessary.

 

[plasticpigeon]

Thanks Toby, yes my bricks look very similar to your bright red brick in the mmiddle except that there are 8 holes rather than 3. I shall have to try a better quality diamond cutting disc. Do you have any recommendations please?

Bolster and big hammer? Worked for mine when building a small retaining wall for a trench

Agreed. I've always though that's what the holes were for, to make splitting the bricks easier. Since they won't be visible in the final construction a nice clean cut isn't really necessary.

As far as a bolster and hammer is concerned, it is about as appropriate for this job as it is for cutting window glass, and yields very similar results!!

 

[Flyfisher]

That's not my experience. Perhaps if you need a very precise cut for bricks that will be on show, then powerful diamond cutting machinery will certainly do the job. But if you just need to cut a brick into half or thirds in line with the existing holes then a bolster an lump hammer will definitely work.

You said the job is "nothing too grand" and the engineering bricks are only to be used for the foundations and inner skin, so they won't even be visible will they?

Sure, the cut edge will be a bit rough but why would that matter if the bricks will be invisible in the end result? Perhaps it depends on the number of holes in the engineering bricks? The ones I've used had three 'slots'. Perhaps eight holes makes it more difficult not to shatter the entire brick?

I recently replaced a drainage cover over our septic tank and replaced a course of degraded bricks with engineering ones using only a bolster and lump hammer to cut a few of the bricks. Seemed to work well enough for 'invisible' bricks. :wink:

 

[Toby Newell]

You can get pleasingly accurate cuts with a little practice and a brick hammer on commons or first grades, just chip carefully in a line and the brick tends to fail in that plane. Engineering bricks are too dense to allow the crack to propagate and tend to shatter.

I don't know any specific diamond blades to recommend, but I have used plenty of diamonds in the past and like all drills, sawblades, carbide cutters, abrasives etc there are orders of magnitude efficiency differences between the cheap and the expensive.

It's rare that an expensive diamond blade will work out worse value for money.

 

[stuart45]

Wire cuts are a bit more difficult to cut than Flettons, especially if you only need to nick a bit off the end. They can be cut with the trowel, or a good quality brick hammer. However on face work a diamond blade is normally used.
As you are in the footings what sort of cuts do you need?

 

[plasticpigeon]

As the wall is circular and in flemish bond, I am having to shorten the inner stretchers. I can tell people don't really believe me but I can't cut these bricks with a hammer. I have cut the 3" wire cut stock bricks on my house with a bolster chisel and I can knock bits off with a brick hammer and they are quite controllable, but honestly these engineering bricks are like porcelain, they just shatter unless I can cut them with a cutting disk. I have done 20, but they have taken a long time and it is pretty arduous.

 

[stuart45]

The 8 holed ones are worse, and using a 4 inch grinder is a bit harder than the 9 inch one. Normally a clipper is used on site if a lot of cuts are needed.
How are you forming the curve? eg fixing a steel rod and using a trammel.

 

[plasticpigeon]

Hi Stuart, yes just that, a steel bar concreted in and a trammel. Can you recommend a superior cutting disk? I believe these are class B engineering bricks.

 

[stuart45]

I've got Norton segmented at the moment which seem to cut well enough. Screwfix stock them, although the cheaper Erbauer ones should go throw class B's without too much trouble.

 

[plasticpigeon]

Thanks Stuart, I shall try one, £12.99 isn't too much to risk!!!

 

[Toby Newell]

We had exactly the same problem on Friday, the engineering bricks just shattered when we tried to cut them the traditional way, with a brick hammer, I think they are less porous so the crack cannot propagate to the the other side so easily and so tend to shatter, swapping them out for class B's would be easier to cut whichever method you use and wouldn't cost your sponsor much more money.

 

[stuart45]

You could also use Header bond for the unseen footing courses to avoid the cuts.

 

[CliffordPope]

Score lines with the angle grinder first, then clout with the bolster and big hammer. Don't hit too hard. First go sets up a weakened fault line, then turn the brick over and hit from the other side.

 

[plasticpigeon]

Bolster will never work for this, but I bought a Norton disc, and it works very well. Obviously the cheap Rolson disc that I got at the local hardware shop wasn't up to scratch. Some diamonds are more equal than others it seems.

 

[stuart45]

Glad you got it sorted. Sounds like you have got an interesting job to do. I have seen quite a few 'pro' bricklayers go wrong on circular work.

 

[plasticpigeon]

Thanks for the cutting disc recommendation Stuart! Well I'm making it up as I go along a bit. I have a steel post concreted in which is as close to vertical as I can get, and an adjustable length and angle trammel that I made myself. So far so good. I hope to do this within the next 8 weeks as that is when the judges are coming round!!! I'll put up photos if it ends up half decent. If all goes silent I have messed it up!

 

[stuart45]

Sounds like you are getting it set up well. With regard to keeping the courses level I find it a lot easier to fix some bits of 2x1 at the base as datum pegs and mark the courses on a gauge rod. That way as I go round I can check the brickwork is level. Going round with the spirit level on it's own often ends up with an error as you get round to the starting point. It surprising how small errors show up when you stand back and look at the wall.
Looking forward to the photos, I'm sure it's going to be a great job.