The All Important First Cut
There are very few universal rules in the world. One rule that comes pretty close is that you should always take it slow and easy when making the first cut in any material using any tool.
The importance of this rule is obvious if you are cutting steel rod with a hacksaw or starting a drill bit in stainless steel plate. The importance of this rule may seem less obvious if you are running wood through a tablesaw or making the first pass with a router bit. It is also equally true in much less obvious applications.
When cutting MDF with a CNC router and a diamond router bit the true professional will very carefully test the set up with some slow passes to make sure the programming, the fixturing and the tool are all correct.
Even a highly non-obvious operation such as using EDM to cut carbide blanks to shape is much more likely to be successful if there is a couple, or at least one, slow pass to start.
Making the first pass slowly allows you to test the design and security of the fixturing of the part without inviting catastrophe.
A slow first pass has the effect of providing an extremely fine, micro-honing of the tool before it begins the serious work.
With a hacksaw on the steel rod or the drill bit on the stainless steel plate, it is very obvious that you need to start slowly since the tool will slip and skate over the surface of the metal otherwise. Once you have cut a small small hole in the plate you can supply a great deal more speed and pressure knowing that the cutting edge will remain where it should.
The same holds true with much more sophisticated applications such as the diamond router bit or the EDM. Getting the cut started properly means a much better cut with cleaner edges and it also means much longer tool life.
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