Laser Pointer

[Andy J]

Pondering how a laser pointer could be used as an alignment aid for a building board.

Thinking along the lines that a fixed position laser could act as a reference line say for the centre of the fuselage or the leading / trailing edge of the wing. So would this work or is is just a high tech replacement for a ruler and pencil?

Aware that the majority of cross hair laser markers sold for building work have quite a thick beam so how would I narrow down any resulting beam from say a cheap laser pointer?

Edited By Andy Joyce on 29/12/2020 16:46:37

[Piers Bowlan]

I have a builder's laser which is great for decorating, general DIY jobs and I am always finding new uses for it. I have never considered using it for building a model. As you say, the beam is quite wide but it could still be useful.

[Andy J]

Certainly some form of fine position adjustment would be required as I find its a bit difficult to position a builders cross hair laser and assume a laser pointer would even be more prone to movement.

From recent wallpaper experience I think my old plumb bomb works better than the line drawn by the laser as found the beam too wide. On the plus side it did do a good job of making sure a 2.4m square concrete slab was level for my new workshop.

[Dad_flyer]

Diffraction puts a minimum possible size on a laser beam. For a red laser beam to stay about the same size for about 2m it needs to be 1mm diameter. Builders lasers are set to larger diameter to work for longer distances. Eyes are remarkably good and consistent at judging the centre of something, so a 1mm wide line can give better than 0.1mm alignment.

A telescope-type theodolite can see small features much better because it has a large lens. But then it needs to be re-focused for different distances.

[cymaz]

A line of nylon twine might be a better idea. Between two points there is nothing straighter.....or cheaper.

[Brian Sweeting 1]

Looking at a commercial laser catalogue it seems line widths can range from 0.2 to 0.6mm on certain types.

However if you want to test the theory try searching on something like 'cross hair laser' and quite a range come up with prices around £4 upwards so not too expensive to experiment with.

[Dale Bradly]

I have a cross hair laser, use it all the time when building for checking things (e.g. when mounting wings/tailplane/fin can be checked against the already mounted fuse/wings/tailplane/fin).

A pointer i've never used, but often considered it would be useful in awkward situations, e.g. you could install the engine, hang the laser pointer on a skyhook pointing down the needle valve barrel, then mount the cowl, and the pointer thus indicates exactly where the drill the hole. Same idea could work on wing mounting bolts, remote switches, pushrod exits.... Funny, it's the lack of a skyhook that has prevented me from actually doing it though.

[Brian Cooper]

There are certainly some interesting suggestions here for employing a laser light.

Me?... I use one purely as a toy for winding-up the cat. . He goes bonkers chasing that little dot of light.

[Kevin Fairgrieve]

Been using them for years.

Not pointers, but similar.

Kev

[Andy J]

Kevin, fail to see how the 3 units improve accuracy, as there is no means to ensure the beams are parallel to each other.

[Piers Bowlan]

Looks pretty though!

[Kevin Fairgrieve]

Posted by Andy Joyce on 30/12/2020 09:47:12:

Kevin, fail to see how the 3 units improve accuracy, as there is no means to ensure the beams are parallel to each other.

Just set them along the lines of the plan. So if the plan were to be wrong.

Looked straight enough and it flew straight and level off the board.

By no means a scientific approach.

Kev

[Geoff Gardiner]

I made this, which is proving very useful. It clamps onto a tripod.