It is often necessary to drill a hole in something using an electric drill. Moreovermore, it is often desirable that the hole should be perpendicular to the surface. Ensuring this perpendicularity, however, is not straightforward.

One solution is to use a bench drill (which lowers the bit vertically onto the workpiece), but this is not much use when you want to drill a hole in a wall, an okapi, or some other thing too large to fit under the bench drill. For hand-held drills, the best you can do is to look at the angle of the drill from above/below and left/right, and try to keep it all square as you drill.

Howevertheless, a simple solution suggests itself, involving lasers. One low-power laser, with its beam split into eight parts, should be sufficient. Just arrange it so that the beam is split into four pairs of beams (one pair above, one below, one to the left, one to the right), wherein each pair of beams converges. For example, the top pair of beams will start out two inches apart, but converge to be only a quarter of an inch apart a few inches in front of the drill chuck.

Now, it becomes easy to hold the drill square-on to the wall - just tilt it up/down until the two dots above the drill have the same spacing as the two dots below. Likewise, tilt it left/right until the two dots to the left have the same spacing as the two to the right. The same setup will work regardless of the length of the drill bit or how far into the wall you've drilled.

[Some time later... use a circle of laser light instead - much simpler.]
-- MaxwellBuchanan, Nov 14 2018

BullseyeBore http://www.bullseyebore.com/
[xaviergisz, Nov 15 2018]

Spinning laser center finders https://www.google....laser+center+finder
Shown by Dan Gelbart in one of his videos in 2013, since built by many people [notexactly, Dec 03 2018]

I think you could get away with 3 pairs, at 120 degree intervals.
-- Loris, Nov 14 2018


Interferometry would be more precise.

Or since you're spinning a motor, put the laser on the spinny part at a pleasing angle. (Balance the weight out, too). Or maybe just a spinny mirror.
-- RayfordSteele, Nov 14 2018


//3 pairs, at 120 degree intervals.// You could, but I think it would be fiddlier to use, since pitch and yaw movements would be interlinked. Easier to have one pair for pitch, one for yaw.

//Interferometry// In what way? If it gives a big response to very, very small movements it might be too sensitive for a handheld drill.
-- MaxwellBuchanan, Nov 14 2018


Actually, hang on a moment. Forget the paired beams. Just have a lens that projects a circle of laser-light around the drill bit. If the circle is an ellipse, you're off.
-- MaxwellBuchanan, Nov 14 2018


That brings up an interesting point on judgment. I suspect we can better tell simple distances as a comparison between points than the ovality of an oval, even though the oval would contain every relevant point.

The interferometry of course would be an appeal to our halfbakery nature for overkill.
-- RayfordSteele, Nov 15 2018


I just did a quick test in Illustrator, and it's very easy to tell a 30mm circle from a 28x32mm ellipse. You can even see that a 29x31mm ellipse isn't quite right.

Somebody who knows geometry should be able to tell me how many degrees error that equates to.
-- MaxwellBuchanan, Nov 15 2018


Looks like such a good idea that its baked.
-- RayfordSteele, Nov 15 2018


(+)

and cool link.
-- 2 fries shy of a happy meal, Nov 15 2018


Well, damn. BullseyeBore is exactly this. Sadly not available for purchase yet, though.
-- MaxwellBuchanan, Nov 15 2018


There are drills with spirit levels built-in... not too difficult to imagine one with angles as well (for surfaces with a definitive idea of up and down, of course).

Alternatively, a rectangular body drill : square up to the hole with a piece of accurately cut angle-iron.
-- FlyingToaster, Nov 15 2018


Wouldn't a drill with massive gyroscopic fly wheel built in do the job perfectly?
-- xenzag, Nov 15 2018


// pairs of beams ... wherein each pair of beams converges //

Will this allow you to maintain exactly sixty feet above a German reservoir, at night ?
-- 8th of 7, Nov 15 2018


Having a massive flywheel on the drill might make drilling tight spaces challenging.
-- RayfordSteele, Nov 16 2018


This boring idea and the link are much better than my solution which is to affix a grinding disk to the base of the drill. I would drill the hole at any old angle then continue on until the grinding disk FORCES the surface in question to conform to perfect perpendicularity to the hole just drilled.
-- AusCan531, Nov 16 2018


There 'are' drill plunger attachments which will let you align to whatever angle you wish... if it isn't a Mandela effect thing.
-- 2 fries shy of a happy meal, Nov 17 2018


A tiny stick on filter to the drills light (a feature on newer battery drills) would supply the circle needed. The circle doesn't have to be at the drill point. It could be even be an oval that when orientated correctly displays round.
-- wjt, Nov 17 2018


BullseyeBore claims to have patents granted and pending. However, spinning laser center finders have been baked and WKTE since at most (because that really makes more sense than 'at least') 2013: [link]
-- notexactly, Dec 03 2018



random, halfbakery