Bullet Proof Laser

I have had the laser on my Monster hollowing rig crap out twice since I bought it last May. Randy has been totally responsive, sending me a new module, no charge, no questions asked, on both occasions. I was looking at the guts of these little modules and realized why they are failing. The laser itself has three tiny wires protruding from the back that are attached to a small chip with very tiny soldered joints. Vibration transmitted through the mounting stem and rail is causing these connections to break. The chip is housed in a small brass capsule and there is a heat shrink wrap around the bottom where the soldered joints are.


While I was waiting for my replacement, I picked up a small laser pointer at Office Max (eleven bucks) and hacked the plastic shell to get the little laser module out. It's almost identical to the ones that come with the Monster except for no brass capsule and there's a small momentary contact switch on the chip. I figured I could "jury rig" this to get me by until the new one came. I ended up cutting the plastic shell down and filling it with JB QuickWeld epoxy (after popping switch open and flipping over the little dimple so that it was always on). I did this mostly because it was the only way I could come up with the get the thing to stay together. But then I realized that with the entire chip encased in epoxy, this would probably prevent the vibration from causing the soldered joints to break. This worked out OK except that the whole thing is about five times bigger than the little brass capsule the Monster laser is housed in. Not really a problem unless you are trying to navigate it through a Jeff Nichol steady!


When I got the new module from Randy, I slipped the shell off, carefully cut away the heat shrink tubing and filled the shell with epoxy, being careful not to disturb the chip or the contacts. Once it set up, the back of the laser module, the contact points and the chip are all solidly encased in epoxy. I'm hoping that this will prevent the laser from failing again. So far I have gotten an average of eight months of light use out of one. So I will have to see how well this holds up over the long run. If I remember, I will report back after another eight months and let you know how well it's holding up.


Oh, and one other thing… if you do this, be careful not to get any of the epoxy on the laser lens!!!

David, a report back to us would be great. But remember to report back to Randy on this as well. May be something he can incorporate into his build process.

David,
I've had my home built laser since late 2009, and only recently started encountering what you're talking about. I found a little 'wigglin' would help restore the connection. I may try what you've done, essentially some minor potting of the contacts. Great idea. Nice that Randy has been responsive, I suspect from what I've heard he'll improve the design to be more robust.
If you ever want to try making your own mount, I use a low-wattage (3w) laser diode from Digikey. PN VLM-650-03-LPT-ND and with it I use a 2AA battery pack SBH-321AS-ND. The laser runs about 9 bucks, the battery pack less than a dollar.
I've used a pen type laser and it's actually too bright for my liking, actually difficult to look at. Could be that I'm just used to lower wattage light.

Anyway, I suspect mine after 2 years is ready for replacing (I have a spare), but I'll probably try potting the old one as an experiment. I can easily see the connections you refer to.

interesting. I haven't had any problems yet, but haven't used it too much either.

Very interesting and timely... My laser broke a few months ago on my monster rig. It broke in exactly the same place that yours did. I inquired about a replacement laser from Randy, and I was told they were $40. Being the tight wad I am, I bought a $3 laser pointer off of Ebay. I drilled a scrap of wood to fit over the end of the laser arm with a cross hole drilled to hold the pointer. When I push the pointer into the hole, it depresses the button to turn on the laser. Works like a charm!

I made my own laser setup, using an inexpensive laser pointer as the basis for the light end. I've been using it for several months and it's never crapped out. Like others here, I potted the entire electronics part with 2-part epoxy, so there is not opportunity for any of the connections t wiggle themselves loose.

So... I learned something from this. Next time anyone asks, I will nonchalantly shrug my shoulders and say "Yeah.... I potted the electronics" like I have a clue what I'm talking about. I'm pretty sure I can pull it off...

Where are you all taking them apart? At tip where bulb is or where battery is unscrewed apart at?Guess i'll try one for myself. I just bought 3 lasers due to not lasting very long.

David,
This may be too late to help you, but I just found the site where I had bought laser modules before. I measured their diameter and they are identical to the one on my Monster rig. The voltage looks to be the same (two AAA batteries), in fact I used the identical battery holder on mine that is on the Monster. The link is http://www.virtualvillage.com/super-...07900-021.html. Only $4.95, so buy a couple just in case. One comment - the front part will focus the beam, so if it is elliptical, just twist the front bezel and you will get a round spot.
Dave

Yup... those look like the same units. Thanx for the link. BTW the Monster laser arm has a pinhole drilled in which serves to focus the light beam.

Quote:

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Originally Posted by Dave Mueller

David,
The link is http://www.virtualvillage.com/super-...07900-021.html. Only $4.95, so buy a couple just in case. One comment - the front part will focus the beam, so if it is elliptical, just twist the front bezel and you will get a round spot.
Dave

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Thanks Dave....mines been a little flaky lately, I just bought a back up.

I got a bit wordy in the explanation here, but the last line is my idea.

In a former life, i used to design electronics for vibration sensors. Wires failed like this all the time, if you don't tie them down softly, and control the bend radius. I even heard stories of thick stainless steel hardline coax wiring failing on gas turbines because they hadn't hose-clamped it down every few inches, but that was a TON of vibration.

For regular insulated wires, epoxy potting wasn't always the answer. When we potted wires in hard epoxy, the failure moved from the tight bend at the solder joint, right up to the tight unsupported bend where the wire exited the epoxy. The trick, when partially potting, is to keep a long subtle transition from the "rigid fixed termination of the wire" to the "freely vibrating unsupported wire", otherwise the unsupported mass of the free wire just hinges back and forth on the rigid part until it fatigue cracks, and fails just like if you were to bend a clothes hanger in a vise back and forth 60 times a second. And attaching bigger wires doesn't help, because there is just more freely vibrating mass working to fatigue the tight radius.

Another simpler approach is to line the wires and housing with soft rubber or foam(not over-bending the joints while installing foam). The foam provides a soft gradual damping, that doesn't concentrate stress at the joint, and greatly reduces the free vibration of the wire. There is also a soft insulating liquid foam that works spectacularly well for this sort of thing, because it complete conforms to the wires/electronics, and supports all free unsupported masses with a damping material. I cant remember who makes it though. Resist the urge to just use silicone caulk: IIRC, it will offgas acetic acid when it warms up, which sealed against the electronics results in corrosion on the circuit boards, and subsequent failure. I dont know that we ever tried other types of caulk, because we had to work at high temperatures. In a closed cavity, you want something that cures without evaporating a solvent.

The simplest solution may be to stuff some soft urethane foam snippets in the laser housing to damp the wire. You could also line the clamp that holds the OD of the laser with thin rubber or foam, which may slightly reduce the amount of tool vibration making it into the laser housing/wiring.

Hope this helps....
Don

After reading the title again, it occurred to me that a laser designed specifically for handgun use would almost have to include some serious provisions for isolating the shock and vibration of firing from the laser electronics. The cheap laser points are probably not designed to handle vibe at all.

Just a thought,
Don

Quote:

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Originally Posted by Don McManus

After reading the title again, it occurred to me that a laser designed specifically for handgun use would almost have to include some serious provisions for isolating the shock and vibration of firing from the laser electronics. The cheap laser points are probably not designed to handle vibe at all.

Just a thought,
Don

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Dealer cost on a Crimson Trace laser for a handgun is approx. $160...............MSRP is about $275........

I have one on my most-carried carry gun, but wouldn't spend that much on one for the lathe..............(how many times have I said that before ?!?!?!?!?!!!!) :D

Rich

"Dealer cost ...approx. $160..."

Right. I'll stick with the five dollar modules thank you. Besides I could never figure out if I should get one for a Glock or a Beretta.