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Replies

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  Kieran Ray November 23, 2014 at 12:34pm

  Draw your circle then cut as close to the line as possible. You will probablprobably need to use a 4 inch grinder with a diamond blade. Then once the main stay is out neaten it up with the grinder. I'll sometimes use a mortar rake blade for this as it gets a smoother edge than a normal cutting blade.
  
  Failing that you could just get a recessed cover.
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  MWJONES November 23, 2014 at 12:49pm

  Cheers Kieran, ive got a recess man hole which is 30cm round which I am trying to put the 600x600 slab over. Then i would like to try and put the piece I cut out into the insert.
  
  A mortar rake blade might do the trick with a steady hand.
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  Ian Street November 23, 2014 at 1:26pm

  You used to be able to get 'cone' diamond blades for a cutter, to cut circles. I know, (a few months ago), that they are still available.
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  Neil Petrie BSc Landscape Mgt November 23, 2014 at 2:05pm

  I would think a 4" grinder with diamond blade and a perfectly scribed circle would work. Carefully and slowly cutting round and round and round and round until it breaks through would do the job. Without having done it any other way that's what I'd opt for if I needed the inner circle in one piece.
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  Thermo November 23, 2014 at 5:00pm

  what type of paving is it?
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  John Baker November 23, 2014 at 5:13pm

  Might be easier if you have the joint of 2 or even 3 slabs in the recessed cover
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  MWJONES November 23, 2014 at 5:13pm

  600x600x50mm concrete slab
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  Thermo November 23, 2014 at 5:20pm

  you're unlikely to get the two pieces out of one slab, extremely unlikely (well neigh on impossible actually). mark your outer ring and use a 4" grinder to score the circle and go in as deep as you can. then go inside the line with a series of straight cuts, so you end up with a marked circle from the first cut, then an octagon or similar inside of that, after you've done the rest. then work out from the centre cutting out sections until you can remove them and tidy up the edge of the circle. your only going to see the top edge of the slab, so it doesn't matter what the depth of the slab looks like.
  once you done that you can use the cut slab as a template to get the alignment on the pattern of the other slab and mark it roughly for the inner piece of the manhole, so it looks like its come form the same slab with pattern etc. then mark it accurately for fit on the manhole and that's an easy cut, again just score the line first and then cut.

  probably sound really complicated but its quite easy. if I had 5 mins and a video camera it would be easier to show you.....but I don't and its raining and dark!

  
  oh and its a lot easier with a decent diamond blade!
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  MWJONES November 23, 2014 at 5:41pm

  Cheers,
  
  We will try and see how we get on.
  
  Marl
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  Colin Hunt November 24, 2014 at 9:02am

  Now that I have stopped the hard landscaping and concentrate on maintenance, I miss these challenges!!! Have used subbies and had to show one how to cut a 135deg mitre on bull nose kerb edging blocks. After a quizical look he said "but why can't I just butt two together and fill in with muck?"
  
  Keep up the good work guys!!
  
  Thermo said:

  you're unlikely to get the two pieces out of one slab, extremely unlikely (well neigh on impossible actually). mark your outer ring and use a 4" grinder to score the circle and go in as deep as you can. then go inside the line with a series of straight cuts, so you end up with a marked circle from the first cut, then an octagon or similar inside of that, after you've done the rest. then work out from the centre cutting out sections until you can remove them and tidy up the edge of the circle. your only going to see the top edge of the slab, so it doesn't matter what the depth of the slab looks like.
  once you done that you can use the cut slab as a template to get the alignment on the pattern of the other slab and mark it roughly for the inner piece of the manhole, so it looks like its come form the same slab with pattern etc. then mark it accurately for fit on the manhole and that's an easy cut, again just score the line first and then cut.

  probably sound really complicated but its quite easy. if I had 5 mins and a video camera it would be easier to show you.....but I don't and its raining and dark!

  
  oh and its a lot easier with a decent diamond blade!