I was drilling large tuner holes for a u-bass cbg when the wood let go. Only real harm was the time lost and the small piece of wood, but some anger management was required. Not sure if it was the wood or my lack of clamping. In hind site, I drilled the holes first on the replacement piece, then scarfed, and lastly I will thin and shape the head stock. It made me think about the proper sequence of events, and if nothing else, I will try do the risky part first so as to minimize any losses. Also if I do pilot holes, keep them real small and the wood well clamped!
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steel drilling bits all have HSS on the shank, standing for high speed steel.
Bits made for wood should have a slightly longer point on them (narrower tip angle) to allow them to cut their way into the wood rather than to splinter the wood out of it's path.
Wood drilling bits also tend to have the flutes (at the cutting part of the sides) double ground, or having two distinct ground surfaces on the outside faces. This leaves less steel in contact with the wood as it turns inside the hole, so it doesn't burn the sides of the hole with the heat generated, or overheat the bit.
A steel cutting bit will have slightly hollow, but smooth single ground sides and not really suitable for wood.I've use steel bits with success ,like john said no need for pilot holes just use a bradpoint or a sharpened(pointed)nail.no need to put pressure on the drill,let it do the job as intended to cut!as always use correct tools for the job.
That looks like you've drilled a small hole (way too big to be called a pilot hole) and then gone in with a relatively blunt HSS twist drill. The inital hole has allowed the larger drill bit to grab and act as a wedge and split the wood. In future, just mark accurately and use a bradpoint bit of the correct size - no pilot hole necessary. A bradpoint is effectively a "downcut" bit, designed specifically for wood, whereas a twist drill is designed for metal. In this case, it looks like that it's the over-large "pilot hole" that's caused the problem - without it there's a good chance that the drill would have gone through cleanly in one steady pass, but better to use a bradpoint.
Sorry to see this happen. We all have had our "oops" moments. One trick I find helpful when drilling holes, besides pilot holes first before the larger diameter, is to place a piece of wood underneath the section you are drilling. This allows the bit to pass through your work piece without "blowout" or fragmentation. In other words, it stabilizes the work piece, and prevents the wood from possibly fracturing when the bit passes through the back.
Many possible reasons Kigar, a fault in the wood, too much pressure with the drill, or a poor drill point that needs thinning etc, Forstner bits are a good investment for near edgework, but without them, a pilot hole with a diameter less than the core dimension of the finishing drill should do the job ok