Sawing to length is one of the beginnings steps in making a metal fabrication, and it's crucial to get it right. There's more to cutting material to length than just throwing the stock under the saw, especially when we want to deliver a high quality finished product. Over the years we've learned a lot about the best way of doing the job, and we're going to distil all that knowledge into five tips for metal fabrication sawing.
Know what accuracy you need
If a fabrication is going to be square every piece must be sawed precisely to length. Angles must be spot on too. Plus or minus a half degree isn’t good enough, because it puts the whole assembly off.
A poor cut leaves burrs that need removing before doing anything else. A rough and uneven cut face complicates assembly and welding, so additional finishing may be needed. Surface contamination needs removing before welding.
Pick the right tool for the job
There are two options: the cold saw and the band saw, and they do slightly different things. The cold saw has a circular blade, produces accurate lengths, and can be angled for miter cuts. Cut face quality and accuracy are good but as it’s used for cutting single lengths it's slower than the band saw.
Band saws are good for cutting layers or bundles of stock clamped together. This makes them faster per piece, although for single lengths a cold saw might be quicker. Disadvantages are inferior edge quality and accuracy.
Know your material
In the ideal world you'd match saw tooth geometry to the properties of the metal you're cutting. Changing band saw blades is awkward, so the temptation is to stay with a general purpose pattern. Cold cut saw blades can be swapped out more easily, so there's no excuse for using the wrong geometry.
Interrupted cuts, as when cutting tube or bundles of stock, are hard on the teeth, so there are geometries for this type of work. The other point to note is that thinner sections need a finer saw tooth pitch. Ideally six to 12 teeth should be in the cut at any time.
Sawing is a metal removal process akin to milling. Chips can clog the teeth and friction generates heat which can damage both blade and workpiece. Coolant flushes away the chips, carrying some heat with it, but more importantly, it lubricates the cutting process, helping achieve a good finish and an accurate cut.
Sawing for metal fabrication isn't as simple as it looks. Get it wrong and you'll be unhappy with the finished job. Hopefully these tips have convinced you we know what we're talking about!