Today my colleague Stide and I were in Nijmegen again. We are presently replacing a number of ornaments on the South Portal of St. Stephen's Church all of them (20 trefoils, 7 consoles, 20 crockets and 3 capitals), and right now we're arriving at the removal of the last blocks. There were still two capitals to be taken out, and of the seven consoles that I've copied there were still some residual blocks left in the wall. These too obviously had to come out before the new ones can be put in.
The point is just that these kind of blocks are fixed very deeply inside the façade; the larger blocks even more than 30 centimeters. How to get them out without damaging the surrounding stone? If you read the title of this post, you will know the answer: with a chainsaw (read here an earlier post about . chainsaws for stone etc).
The principle of a concrete chain saw is a machine like an ordinary chainsaw, but then with a chain with diamond cubes and a water rinse system. In the past I've worked a lot with stone chainsaws, and not always with pleasure: these machines are heavy and you need to use considerable force to keep them steady. In the beginning there were only chainsaws on hydraulics, with heavy hydraulic ducts so you had to drag and lift these things all day. Later, versions on gasoline arrived. That was a great improvement, because you didn't need a separate hydraulic station on high voltage power anymore. However, many times the air filter would get wet (the chain is cooled, lubricated and flushed clean with water) and then the engine would choke. Furthermore that thing ran on a very greasy oil mixture which meant you had to work in exhaust fumes and noise all day. Later, after the first supplier ICS also Husqvarna and Stihl came with a concrete chainsaw.
But yes, if you need to cut so deep into awkward corners, then what do you do? Get into the fumes and noise anyway? And then I heard of the electric chain saw for stone, the Cardi Coccodrillo35, also known as Renova here. The solution! I thought. No noise, No exhaust fumes, more compact and slightly lighter (but still almost 10 kilos). From several sides I was strongly advised I'd better take a petrol version, because it's stronger. ‘Well, so it'll have take take a little longer,’ I thought. ‘I guess that's worth it.’
Well, it didn't disappoint me. The thing went very smoothly through the tuff after all. I could cut quite easily all around the blocks, after which we could break them loose from the rear side. Below is a brief impression: specially for this blog Stide has filmed how we cut loose one of these blocks . At the end you can well see the saw technique: each time putting the tip of the blade into the stone, then with a little pressure the chainsaw pulls itself quite easily into the stone.
(Unfortunately the sound disappeared halfway through, but the idea is clear.)
The saw of 3500 watts can cut up to 35 cms deep, and square holes of approximately 12 x 12 x 35 cm are possible with it, up to very large things. Wish I had this before, that would have saved a lot of work!
Update 22 July 2015:
By now, I once again found out that petrol nowadays has a very short shelf life. My chain saw for wood wouldn't start. I'd almost forgotten it, but gasoline doesn't keep for long. If you don't use it on a weekly basis or use a special addition for it, gasoline will gum up inside the tank and motor within half a year, with all its consequences. It forms a sticky layer and can also damage rubber parts. In any case, the engine will not start right away; you'll be pulling at the start cord until you're dizzy and then you will have to clean out the whole motor too. In the old days you could leave petrol standing for years, but nowadays there are so many chemical additives in it that half a year already is too long. Yet another reason why I am very happy that I've chosen for an electric machine!
Update 8 november 2016:
Recently, Stide needed my chainsaw to cut off a block of stone from a statue. I took this opportunity to make the video below. Strikingly Stide, although he still had to get used to the saw, and although the stone is very hard, needed less than 4½ minutes to remove that block. With an angle grinder he would have had to cut the whole block to pieces, and it would have taken much longer. Cardi coccodrillo review, review, concrete chainsaw electric