Any laser guru's out there?

[Robert Edington]

I admit I know nothing about lasers. So I need some help. I want to use a laser for tool positioning. I ordered a 650nm, 5 mW, Red laser module with adjustable focus. 4.5-5volt. I also ordered battery case to hold 3-AA batteries, giving me 4.5volts.
All I want to do is project a red dot on a paper plan to guide a tool. The laser will have to be on for a while. Maybe 30 minutes at a time.
Will my plan work?
Do I need more hardware?
Will the battery supply be adaquate?

I know many have used lasers to position tools for hollowing rigs. And that is essentially what I am doing.
Any help would be appreciated.

Thanks
RP

[Dan Hintz]

I would skip the battery pack and just get a wall wart. Also, make sure the laser module is designed to current-control the diode... if it's a bare laser diode, you'll burn it out in a heartbeat simply attaching it to a voltage source.

[john taliaferro]

I use a old phone charger in a outlet that is wired with the lights . The battery packs could not take the vibration , hot melt the wires to the mount ,its hard to solderer them back .

[Brice Rogers]

The little laser modules are very inexpensive/cheap - - only around $4 or less on ebay. So, if you have a problem, you could inexpensively replace it.

I suspect that most cheap lasers rely on the batteries to limit the current to some extent. At least that is how nearly all of the cheap LED flashlights work. If you have a problem and have a short life on the laser, go to radio shack and buy a small pack of resistors. Put them in series with the power source. Perhaps try something around 47 ohms. If you can measure the current, a value of perhaps 0.020 to 0.030 (or 20 to 30 ma.) should give you good life. If you don't have a meter, try the 47 ohms. If it is too dim, then put two of the resistors in parallel.

If you use a wall wart, get one with the same voltage rating as your laser diodes (mine runs at about 3 volts). Also, keep in mind that many wall warts are AC output. I don't think that it would work very well.

[Robert Edington]

Thanks for your responses. It will take a month or so for the lasers to come from China. I'll let you know how it goes.

RP

[Joe Pelonio]

The laser on my compound miter saw uses 2 AA batteries, but it's hard to see in bright light. My laser level uses 4. Couldn't you just buy a laser pointer and mount it?

[Brice Rogers]

Yes, a person could just mount a laser pointer. The difference between a pointer and a laser module is just the packaging. The slight difference is that the pointer doesn't have wire leads to go to a larger battery pack and you've got to either bypass the pointer switch or figure out how to keep the button pressed. I think that a larger battery pack (a couple of AA batteries) is going to last a WHOLE LOT longer than a couple of button batteries.

I'm in the process of putting together a hollowing system and might use a laser pointer, if I can figure out how to get to the power leads so that I can either put on a larger battery pack or connect a wall wart.

[Marty Tippin]

Getting any kind of decent focus of the laser dot is likely to be a challenge. I bought some cheap laser modules on Amazon to replace the broken one in my Monster hollowing rig and couldn't get anything better than a big red blob out of them. I ended up buying a replacement from Monster.

[Don Bunce]

If you need a laser that will focus down to a pinpoint, this will do it. Not cheap,though....

http://www.lasercenteredgefinder.com/main.html

[Brice Rogers]

Getting any kind of decent focus of the laser dot is likely to be a challenge. I bought some cheap laser modules on Amazon to replace the broken one in my Monster hollowing rig and couldn't get anything better than a big red blob out of them. I ended up buying a replacement from Monster.

Marty, while I don't doubt your first-hand observations I am surprised with that poor quality. I've got a few cheap laser pointers as give-away items from a trade show. At 2 feet, it has about a 2 mm beam. For me, that would be small enough. But when I look on-line (ebay) I looked at a few ads and didn't see any mention of the beam diameter or the beam angle. So it would appear that it might be a hit-or-miss success rate when buying off of ebay or amazon. BTW, on amazon I saw 10 modules for around $7 and free shipping. So, these things are dirt cheap. I also noticed one set of specs saying that it draws 40 ma. and has a 2000 hour life. So, I think that they are driving them pretty hard to get just a little bit more light out of them. If the current was dropped to about 20 ma. or 15 ma., it might extend the life 5-10X or more. (BTW, I'm a BSEE - - who enjoys making chips more than making sparks).