Rod,

It is difficult to improve the shape a laser pointer spot. The "proper" way is to use Spatial Filtering, but that gets rather bulky [and can be expensive]

Unfortunately: Simply adding a pinhole is most likely to be counter-productive, because of diffraction.

… If you haven't already done so; may I suggest you read through this recent thread.

MichaelG.

Edited By Michael Gilligan on 09/03/2014 08:33:55

Clive- you have stated that you cannot focus a laser as it is coherent light- that is simply not true. Light from a laser can be reflected and refracted in exactly the same way as any non-coherent source excepting that laser sources are normally substantially monochromatic (i.e. single frequency/one colour) so chromatic aberation is not the issue it is with wide spectrum sources so focus can be much better. The coherence will make diffraction issues much more obvious however that is a useful property in many ways.

As was indicated in the previous thread, the beam intensity often makes lines appear much wider. By increasing background light levels the apparent line width will decrease. Bright illumination is also good from an eye safety viewpoint.

Billy.

I have just tried shinning the beam from a laser pen through various magnifying devices, watchmakers eye glass 10x, stamp viewer 8x, another magnifier15x and they all enlarge the diameter of the beam "spot". This happens with both glass and plastic lenses.

I bought one of the purpose made laser centre finders, it has a polaroid filter to "focus" down to a spot.

In any event, I find it only useful for setting edges true (ie squaring up a mill vice). Every other setting up task I use conventional (ie old fashioned) methods as they tend to be quicker and I feel more confident in the accuracy of the setup.

Steve

It's worth [briefly] exploring diffractive optics.

… Very clever stuff.

MichaelG.

i've recently watched on (australian) abc 'catalyst' program a segment on cheap laser pointers. Despite legislation limiting power to 1mW or so, many labelled as such were in fact much higher. So What? well, a simple demo pointed such a laser at a balloon. In very few seconds, the balloon burst. Eye damage can occur in a similar time. So make sure that no-one looks directly at it. A bit sobering, really.

-russell

I concur with the previous post. We test all our laser pointers at work and the cheapo imports do often exceed 1mW by a large factor so do be careful. Retina's are not replaceable items. If you cannot get it tested try to buy from a trusted source and don't just go for the cheapest. If you can reduce the output don't run the device any harder than you need to.

Regards Martin

Imported one of these from California when first available 10 yrs ago and never used since.

Have a look at the videos to see how useless they are, need a small narrow beam 0.1mm or less for precise work most are of the order 1mm with spatter so can have error of +/-0.5mm at extremes. Stick to the wiglers or electronic edge finders. If lining up on punch marks spinning a centre drill will be more accurate. Or just touch edge of work with a cutter and take readings from there, easy.

**LINK**

I agree with john, after the original article I made one and found that I was using my eyes to see if the alignment wasCorrect. The  feeler guage I use was much more accurate and repeatable on setting up. For centre points I use a wiggler again it is more accurate especially if used with a dial guage.  I keep the lazer on my key ring to point things on white boards. An inexpensive toy.😳

Bri

Edited By Boiler Bri on 12/11/2014 22:26:02

Hello Nobby.

Lasers that produced a line are available very cheaply on ebay – I’m thinking a couple of those mounted on the mill head would work for finding an edge – one each for the X and Y axis.

Not sure what the beam angle is – the listing I had a brief look at didn’t mention it.

But for just under a tenner for 5 (!) , I might just order some to play around with !

W.

Ps…I haven’t forgotten about the LED bulbs Michael – just been very tied up with helping brother to move house !

.

Thanks … I've been rather distracted too; so not much progress.

MichaelG.

I have had a look at vid 18 Michael and it suffers from same problem as my expensive one I think was around £60 ish 10 years ago.

Beam generated is far too big and or too much spatter to be of any use, reliant more on visual than actual. What it needs is the beam to be 1/10 of that size to be of any use but still wont be as good as a cheap wiggler £5 or electronic edge finder £17, I can honestly get a better visual with a cutter overhead. Ciggy papers another good one.

In saying that did like the home brew laser attachment that might consider only using for larger internal holes, no other accurate use. Also the quick release depth stop but rest of stuff and layout is just gizmos or wrong. Larger or smaller dia hex bar that self centring 4 jaw wont hold, it will be off two of the jaws. Take it he never machines with anything smaller than 19mm shank or does any proper work, machines gonna be very limited in use and so forth. Takes 10 secs to change an R8 or MT collet over with cutter or about 5 mins with an ER but can see his point if machines an ISO.