Sort of wood/ sort of metal related -

Previously to join planks of wood together I used a biscuit jointer but that technology is back in Adelaide, so I'm having to resort to wooden dowels. The drill bits I have here are 'normal' 118 degree pointed bits and without a centre punch can wander (and who centre punches wood?).

Ideally a W point drill would be used (also known as a brad point drill, woodworker's drill and several other names). These have a central spike and a couple of wings so the outside of the hole is cut before the material in the middle is removed. These are also apparently used for sheet metal - the point geometry means that the sheet material is less likely to pull itself up the drill.

I tried buying the ready made item from Bunnings, but they came in a set of 8 for $8, were out of carbon steel, wobbled like crazy and were in the bin after 2 holes. A sheet metal worker I once worked with taught me how to produce them off hand though, so tonight I tried it.
Start with a normal drill bit like this -
P1020014.JPG
The grinding wheel you use must have a sharp corner on it. By holding it so that the tip and the outside of the flute are untouched, the W shape can be produced. The grinder I have here has not seen a dresser for many years but you can get the idea.
P1020018.JPG
The result is something like this
P1020015.JPG
In hindsight looking at the photo I could have gone a little further out towards the edge but it's a 6mm drill, so I might need some better magnification to get really close.

Don would use these for drilling through thin sheet metal but I found that drilling into moderately hard hardwood they are fine (certainly better than the Supercraft carbon steel drill...)

Michael
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