I have long (60cm/23") concrete beams that I want to cut to size to build a small garden wall. They are 15cm/6" high. I know there exist heavy cutter tooling to cut through (concrete) tiles, but it seems to me that won't do for these large stones. So, what do you recommend for cutting these into rather accurate sizes? thanks for any suggestions offered.
There is no easy way to cur concrete I am afraid. I always dreaded and tried avoiding at all costs cutting concrete in any form.. but when you have to then I always used a large grinder..
The problem is (and why i dread cutting concrete) is the discs take a massive hammering and they dissipate while cutting the concrete. I found using disc for cutting masonry very good because they are not too thick (2mm to 3mm are good but need to be reinforced! unlike like stone cutting discs which are 5mm to 7mm) which help cut through faster.
You need to prepare yourself for this.
So I advise wearing a dust mask and wide glasses that cover the entire area of your eyes! Make sure you are far away from valuable objects like cars(some stones might fly out the grinder damages nearby objects) far away from your washing . Keep other people and pets far away.
These are fine..
but these are very good
That is why buying reinforced discs is very important! Many times during cutting discs have failed sometimes right at the start sometimes midway. Make sure the grinder guard is protecting you and the exit path is between your legs. stand quite wide apart but also sturdy. This is also why its dangerous to stand anywhere near it as when a disc ruptures it can fly sideways.
This type of rupture is very rare and years of building I only saw this once.
Usually you might experience the disc splitting layers and small parts will break off.
These grinders on their own are loud and cutting into concrete is just unbearable. You might want ear plugs and also warn any neighbours or something. Also because you cannot hear any thing I would suggest having somebody in a safe area that can turn the main power off in case he needs to tell you something or warn you. Do not do this on your own.
Make sure to rest inbetween several as vibrations and feedback take a massive toll on your arm muscles. You always need to hold the grinder sturdy in case it mis behaves and jumps upwards or something else.
Make sure the item you are cutting are secured properly. They should not move at all. If friction changes like you hit a rebar within the the concrete (grinding some metal with a masonry disc is fine! it only eats the disc slightly faster and makes loads of sparks) then its better the grinder vibrates rathen then the item flying and hitting you in the legs.
You can rent grinders for pretty cheap.
And remember to keep safe.
If you are planning on making cuts deeper than 1 to 2 inches, I would recommend using a worm gear driven circular saw with a 7 1/4" or 8 1/2" diamond plated blade. Some models actually use larger blades. This type of saw is similar to a regular circular saw, but operates at a lower RPM and has far more power. The other advantage of this type of saw is that it lies flat on the concrete as you cut, gives nice straight cuts, and is much easier and safer to use than a grinder. Cutting thick concrete may require taking several passes, cutting an inch of depth at a time. Also water can be flowed on the cut to keep down dust and cool the blade. Hand held grinders are not designed for wet cutting, but heavy duty worm saws are. The most common brand is Milwaukee and can be rented at most tool rental stores. http://www.milwaukeetool.com/tools/saws-corded/corded-circular-saws