The Brew Cabin

I'm trying to cut 50mm concrete block pavors with a bolster to form a 1m radius arc. The blocks are cutting cleanly but are cracking in the middle. I've tried doing this on a bed of sand, wood and even an old concrete slab, all to no avail. What the hell am I doing wrong or am I just a complete eejit?

It's best to cut these blocks with a splitter, but if you must use a hammer and bolster then....

1 - mark/score the top face of the block. Hit the bolster hard enough to mark the block BUT NOT TO CRACK IT.

2 - do the same on the two sides, angling the bolster to create and undercut.

3 - repeat on the base of the block, joining the two 'lines' made on the sides of the block.

4 - turn block over so the face is at the top and strike with a single swift blow with the bolster. This should cause it to fracture along the lines you've scored.

You can lay the block on earth or on sand while you do this, as they hold the block steady and absorb/deaden the impact of the blow without reflecting it back into the block, as it the case if you rest it on a hard surface.

It's so much easier with a splitter - they're eejit-proof! (almost) ;)

Hi Tony

Many thanks for your very prompt reply. Unfortunately, I've been using the method you describe having read your instructions earlier and maybe I'm not explaining myself too well. I'm cutting off angled pieces at the ends of the blocks but they are cracking and breaking off in the middle of the block - nowhere near my cut marks. Am I still an eejit or what?
P.S. Top marks for your website and service!!

So you're trimming rather than cutting, is that right?

If you can hang on until lunch time tomorrow (Tuesday) I'll upload a couple of pictures showing how the blocks are first undercut and then trimmed. It's 20 past midnight just now, and I don't think the miserable gits next door would be best pleased if I started cutting blocks at this time of night! ;)

Thankfully, the rain has held off for long enough to allow me to take a few photos in the back garden....

1 - Lay the block on its side, make sure it's stable and firm, and undercut it by striking on the side...



...sometimes, one good blow to one side will undercut the full width of the block, and other times you need to attack from both sides. As long as the section of block to be removed is undercut, that will be fine....



2 - Once the block has been successfully undercut, turn it face up to commence the trimming operation...



Use the hammer and pitcher/bolster to nibble off a bit at a time. Angle the tool into the block slightly when striking as this helps maintain the undercut....



....and use swift, sharp blows until you've trimmed back to the cut line.



...you can easily trim off chunks of around 25mm at a time, and then tidy the cut edge once you're there or thereabouts.



Done! I used a Pitcher (Pitching Chisel) rather than a bolster, but the procedure, and the results, should be the same. :)

Many, many thanks for your help and advice Tony and, amazingly enough, your method actually works!! (Leave these jobs to the pros, I suppose)

I'd also like to say how impressed I am by someone taking the time and effort (and patience) to pass on their valuable skills to the untutored/thick - and for FREE!!!

Wishing you all the best and I'll be making regular visits to your site as well as recommending you to friends
John Ahearn

Send me some pics of your paving when you've finished, John. :)

Alas Tony - no scanner, which is probably a very good thing for me. All I can tell you is that the finished article is a masterpiece and looks as though it was sculpted by Rodin himself! (After he flattened his thumb with a 14lb hammer)

Keep up the good work
Johnny-Ace

You should treat yourself to a digital camera. :)