Anybody build Dan Gelbart angled laser centre finder?

[PekkaNF]

Dueling banjos?

My intention is to test this concept very close to original DG:s idea:
* You can have drill or whatever on chuck and clamp this over the arbor end. No need to remove drill etc.
* Focusable beam, nominally 5mW red laser. 1mW would be safer, but let's see what kind of results this will do

I have plain spindle bearings on my mill and I think that rotating it will be more accurate than "static" in terms of location of the hole. I don't have DRO, but I could mark string of centres and use this laserfinder to find those marks and then centredrill them. Any suggestions? Make few mm deep holes and measure from edge to edge with sigital caliber, or pins and use micrometer?

I have seen on those links 3 "thou" and other numbers.

Pekka

[Arbalist]

How is DG's unit held on, Magnets?

I believe one user reduced laser intensity by replacing one of the four button cells with a brass spacer.

[BaronJ]

Hi Guys,
I just got one of these    5mw red laser.  Its absolutely useless !
Its far too bright.  The spot is rectangular in shape.  At the distances it needs to be used at a 2.5 X 5 mm spot is far too big.
So this is one to be avoided.

I did try to measure the spot size of mine, and its about 2 mm in diameter, not quite round, it has a small flat on one side.  I think that is why I get a tiny black dot in the centre.

I'm still looking for something like the original one that I got from Aldi.

HTH

Oops forgot to add the picture.

[PekkaNF]

How is DG's unit held on, Magnets?

I believe one user reduced laser intensity by replacing one of the four button cells with a brass spacer.

The one drawing I saw had flat springs on side. Balanced and snug fit. I haven't tried this laser yet. Have to go help my brother - a little logging to do. Literally. Some spruce.

Pekka

[Fergus OMore]

Of course 'Baron' is right. This malarkey( it is) is now age old and has been flogged and flogged. So far, none of these so called 'miracle' modifications from Pound -stores or everythings a buck has been able concentrate what is essentially a toy or at best , a pointer on a children's blackboard.

A million years ago, I used a professional laser alignment kit in motor vehicle re-alignment- but it didn't come from a 'a dime a dozen store'

We have to do better-or buy a wallet spanner or-Give up.

Perhaps, I am being rude- but HONEST

Norman

[Arbalist]

This one is only £5.20 and it says it has a Focusable dot of 2mm at 3 metres. Still 5mw though so probably too bright. I wonder what effect ND filters have on lasers?

http://www.ebay.co.uk/itm/Focusable-Dot-Laser-Module-5mw-Red-Laser-3-5V-650nm-UK-Seller-Free-UK-Postage-/321694174518?pt=LH_DefaultDomain_3&hash=item4ae6778d36

Update: I've checked the 5mw laser pointer I bought many years ago with some of my photographic filters. The ND2 reduces the output a little, the ND10 reduces it a lot, in fact far too much! A standard Polarisering filter reduces brightness only a little irrespective of rotation. A Circular Polariser reduces the brightness and is variable, depending on how the filter is rotated. None of the filters seem to effect the shape of the laser, which in the case of mine is an oval.

I've actually cut square resin filters on a lathe so if it comes to it, it should be possible to cut a small filter for the laser from one of these. I'm thinking an ND4 would make a good starting point. There may well be small filters for sale some where suitable for the job but I've not found any yet.

[BaronJ]

Hi Arbalist,
Did you see my notes about salvageable lenses from dead CD drives ?

[Arbalist]

Hi Arbalist,
Did you see my notes about salvageable lenses from dead CD drives ?

No, do you have a link please?

[PekkaNF]

Hi Arbalist,
Did you see my notes about salvageable lenses from dead CD drives ?

I tried to find it, but could not find it.

I got this laser:
http://www.ebay.com/itm/121212852782?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I was pretty sure 5mW would be to strong, but this was recommended. Soo....I have to check it.

I connected it to two practically emty AA batteries and aimed it to the wall. "Dot" was thin line, about 20 mm long. A little adjustment brought it round. It looked pretty bright - white wall, night outside, some normal living room lights.

Looks pretty bright and big spot on white surface, but then I tried black matte plastic and I was able to make sub mm near perfect round spot - so it seems.

This concept has it's merit and probably also some downside. Probably best to do some testing and see what kind of ecological niece it could have.

Pekka

[Arbalist]

Not sure if it makes any difference but one guy is using a 3 volt CR2032 button cell to power his laser edge finder.

[BaronJ]

Hi Guys,

Re lens for laser pointers et al.
All CD/DVD drives use a single lens about 5 mm in diameter to focus the laser inside, so that the disc can be read.  In all the drives that I have played with the lens is easily removed and can be re-purposed for use with a laser pointer in order to focus the beam.

A Google search "focus laser pointer" came up with lots of hits for doing this, along with lots of warnings.  I also discovered that in the UK at least there is a legal limit on laser power and class.  It seems that 5 mw is the maximum for non industrial lasers.

Note that using a lens does not increase the power of a laser, it only concentrates the beam into a smaller area.  This in turn increases the danger of eye damage, not only due to direct illumination, but also specular reflection, which will be more from shiny surfaces.  I believe that some kinds of safety glasses used in engineering reduce the risk of eye damage from this cause.  I haven't done any research into eye protection of this kind.

HTH.
 

[Arbalist]

I don't have an old CD unit but I've seen these:

http://www.ebay.co.uk/itm/5-x-7mm-Collimating-Lens-Focusing-Lens-For-Laser-Diodes-/271604566954?pt=LH_DefaultDomain_3&hash=item3f3ce4cbaa

I've ordered a small unit and it says it's "Focusable" so I expect it's already got a lens in it.

Yes, as far as I am aware 5mw is the maximum here in the UK and maybe Europe as well.

I can see how important it is for a stationary laser but I'm not sure how small the dot really needs to be for a rotating laser. All the ones I've seen so far certainly weren't particularly small.

[PekkaNF]

mine definately has a lense on it and it does have an effect. I think it has regulator in it, I was measuring current and it lits when voltage is over aabout 2,4V and at 3.00V it draws 19,6 mA. From 2,7 to 3 V current decreases lineary. So...I think it is close to 1mW "laser power" 10% or so?. Electrically it looks good, but I either need to get smaller unit or have a way to adjust it optically.

I should rig it onto something and spin it to see how does it work on garage environment (lighting etc...). maybe I need to get lower power unit.

Pekka

[vtsteam]

I'm just kind of curious -- at the distances we're talking about, small spot size, and using lenses, etc., why does it have to be a laser?

[Arbalist]

I either need to get smaller unit or have a way to adjust it optically.  Pekka

Do you mean the Dot is too big?

[PekkaNF]

I either need to get smaller unit or have a way to adjust it optically.  Pekka

Do you mean the Dot is too big?

It looks like dot is small enough, but it is very bright. This I need to verify, but it looks like this 5 mW laser produces really bright spot, to the point that with even moderately reflective surface the dot "glares". On matte black surface the dot looks tiny.

Pekka

[Fergus OMore]

I have the old Geometer's articles from Model Engineer called 'Microscope on the Lathe'. OK, it is all as old as Methuselah but nemes.co has still got most of it on the 'net.

Again, it was revived in ME or MEW on something similar which became a kit with Hemmingwaykits.

OK. can someone inform me -and others- what are the advantages of this new toy?

Norman

[Arbalist]

It looks like dot is small enough, but it is very bright.
Pekka

Have a look at my earlier post Pekka. You can easily reduce the brightness with a ND filter over the lens. Resin ND photographic filters are easily cut to size and don't cost too much.

[BaronJ]

I'm just kind of curious -- at the distances we're talking about, small spot size, and using lenses, etc., why does it have to be a laser?

Unlike an ordinary light source a laser beam is a single essentially parallel beam of light.  The light from an incandescent bulb is scattered in all directions.
   

[Arbalist]

OK. can someone inform me -and others- what are the advantages of this new toy?

Norman

Best have a look at the video in post #1 Norman.

Quick and easy to use. And, once we've collectively got the "formulae" right, easy and inexpensive to make. At least that's my take on it. I won't know for sure though till I've made one and tried it! 

[BaronJ]

mine definitely has a lens on it and it does have an effect. I think it has regulator in it, I was measuring current and it lights when voltage is over about 2,4V and at 3.00V it draws 19,6 mA. From 2,7 to 3 V current decreases lineary. So...I think it is close to 1mW "laser power" 10% or so?. Electrically it looks good, but I either need to get smaller unit or have a way to adjust it optically.

I should rig it onto something and spin it to see how does it work on garage environment (lighting etc...). maybe I need to get lower power unit.

Pekka

Hi Peter,
The current should not decrease as you said from 2.7 to 3 V !  Exactly the opposite should happen.  You need to prevent the diode from taking too much current by using a series resistor.  If as you say it already has a regulator built in then you can only adjust the voltage to alter the brightness.
Though I suspect that 20 ma current draw could be a problem.  I can't actually get at mine to measure the current, but since the batteries are rated at only a few milliamperes, I would guess at less than a quarter of yours.

I would set it up at about 4 to 6 inches from a surface and examine the dot.  I would say anything around a couple of millimetres in diameter is going to be fine.  Now spin it in the chuck and see how much it wobbles from the centre line.  This will give you an idea of how much thicker the line produced will appear to become when in use.

[PekkaNF]

From what I have read laser diode is very pricess form of LED and can't be trated as such.

Lucily we have well regulated (I hope) laser modules. As said before input current will drop when input voltage is raised.

I did register the comment on neural density filter, probably I have some with my old Cokin filter system. I'm not there yet.

I tested this 5mW laser module briefly with two LR44 cells briefly and it did lit. Maybe bigger sels would be in order, but before cutting too much metal I want to see what effect has:

' Brighness, Probably too dim as well as too bright might be a problem
' Dot size has some bearing, but probably more the shape it hits
' not sure how importat is dot shape
' cone angle is probably inportant

Before getting too workked out with all these variables, I'd like to check which are priority and which has consequence.

Pekka

[Arbalist]

You could make the angle adjustable but apparently 9° works well.

[PekkaNF]

Thanks. I'll try first around 10 decrees or so. Is there any magic on 9 decrees? Sort of new 6?

Pekka

[Arbalist]

Can't find the post now but I believe someone mounted theirs at 10° but with some  small adjustment and found 9° to be best.