21 May 2007

Pizza Screw

Damaged screws

Screws wear off. It is rare that a screw driver fits exactly. Have a little bit of play and the screw driver will work only at the edges. You'll end up with dented screws.

Round nuts

Nuts wear round. Same story, a wrench often does not suit perfectly. In stead of applying force to 6 areas, it will only apply to 6 points. The applied force is the strongest, right on the weakest spot of the nut. Nuts go round.

An improved design?

Could screw driver and screw, wrench and nut have a better grip? Grip on areas, not on points? Even when a bit of wear and tear sets in?

Would a better design be possible?

Yin Yang

A yin and yang design would be very elegant, with two roundings pressing into two bowls.

This works for tightening things, but you'll never un tighten it.

Two circles

So, how about a double yin yang , with two sided roundings, both tightening and un tightening?

Yes, better already. But the outer rim, which potentially can apply most power, hardly contributes.

Bow tie screw

Of course a rounding is easy to let screw and tool fit naturally, like two spoons.

But flat would be even better, so the full power works nicely perpendicular.

A bow tie screw is born.

Pizza Screw

So why just two areas? Why not 3, 4, 5 or 6?

Here comes the Pizza screw!

Advantages of the Pizza Screw

  1. Maximum transfer of force with areas perpendicular to the force direction. The strongest part of the construction takes the most powerful force.
  2. Works to tighten and the un tighten with area that match the screw driver surface, even with a bit of wear and tear.
  3. The screw driver size is quite irrelevant. A oversized screw driver does a fine job. A undersized one damages the screw, has less power, but still does the job.
Till next nut,