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- May 15, 2012
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If you want to tinker with your flashlights, then sometimes you need to separate two parts of the body that have been threaded together, and perhaps glued with a thread-locker.
You probably have a pair of strap-wrenches, and these do a great job in 90% of the cases. They are powerful, fast, and do not mar the surface of your light.
But when even the strap-wrenches fail, here's a different method. It just worked for me on a tough case, so I'm writing it up to share.
I purchased a tube of epoxy putty -- the moldable kind. I mixed up two sticks of this putty each about 1/2" or 1cm in thickness and the length of the circumference of the parts (in this case about 3" or 7.5cm for a light about 1" or 2.5cm in diameter) -- two unbaked baguettes of dough. Then I wrapped the sticks around the light to make two donuts of this putty on either side of the joint. I spread the donuts against the outside of the light so that they each had about a 3/4" or 2cm band of contact with the anodizing. I made sure that no putty overlapped the joint, and that the two donuts did not touch.
Then, I temporarily imprinted the outside of the donuts with the jaws of two wrenches, using a layer of plastic bag between the putty and the faces of the wrenches. In my case, I used a pair of Knipex Cobras with the jaws spread to about 1.25" or 3cm. It would be slightly better to use a pair of crescent wrenches or very large open-end wrenches, but I didn't have them handy. The point here is to turn the outside of the donuts into giant hex-nuts or the equivalent. Take a second and make sure that you massage the putty into a shape that fills the space of the wrench's opening.
Now you have two donuts of putty that are shaped like a hex-nut (or the inside of your wrenches/pliers) on the outside, and have a broad contact-patch of connection with the anodizing on the inside.
Wait a suitable amount of time for the epoxy to set -- in my case, that meant 24 hours.
After the putty was dry, I used the Knipex pliers to loosen the two body parts. It was easy. I applied what seemed like a medium amount of pressure with a pair of 12.5cm Cobras -- the little 5" ones -- and the thread-locker gave up. And this was a joint that had frustrated all of my attempts with strap-wrenches and other devices.
Once the joint was loosened, then I removed the putty. This was a bit fiddly. I used a fine-toothed saw to cut a slot in each donut (the slot ran parallel to the long axis of the flashlight, so across the thickness of the donut). When it was close to the surface of the anodizing -- but not too close! -- I used a screwdriver with a twisting motion to break open the donut. One donut came off in big chunks, pretty quickly. The other came more slowly, and with more picking and fussing. I used my thumbnail to scrape the putty off the anodizing, and to scrape it out of the slight texturing in the ano (the texture and fluting made this donut trickier to remove, but it still all came clean). I have bizarrely tough finger-nails; if you do not, then popsicle sticks or other pieces of wood will do the job of scraping off the putty without harming the anodizing.
The only thing that was slightly tricky with the Knipex pliers -- and would be easy with crescent or open-end wrenches -- is that I wanted to apply *torque* to the putty-nuts, but not *squeeze* the putty-nuts. Squeezing them against the body tends deform the donut and cause it to break away from the body of the light. That's what you want to do after you have loosened the joint, but not while you are still attempting to loosen the joint. With the Cobras, this meant making sure that the handles were squeezed all the way together when I was imprinting the soft putty. That turns the pliers into essentially a fixed-width open-end wrench. You could not do the same thing with a pair of e.g. slip-joint pliers, where you have to bear down with a squeezing motion in order to apply torque. (You could do pretty well with a pair of large vise-grips, because you can dial out to a fixed large diameter with those, too.)
Anyhow -- it worked just as well as I had hoped. It loosened the threads that nothing else was loosening, and it did not leave any marks on the anodizing. I feel good about all of that!
This is still a method only for desperate cases. It has many drawbacks. I had to buy the putty to begin with, and that cost $5 for a non-reusable input. It was slow. In addition to the 24 hours for the putty to dry, it probably took 15 minutes for making and shaping the donuts, and 45 minutes for cleaning the ano after the joint was open (I went slow in order to avoid any possibility of scratching the ano). By comparison, the strap-wrenches are quick and simple and have no incremental cost for an additional usage. They are much more convenient, when they work.
But when they don't work, you can give this method a try.
You probably have a pair of strap-wrenches, and these do a great job in 90% of the cases. They are powerful, fast, and do not mar the surface of your light.
But when even the strap-wrenches fail, here's a different method. It just worked for me on a tough case, so I'm writing it up to share.
I purchased a tube of epoxy putty -- the moldable kind. I mixed up two sticks of this putty each about 1/2" or 1cm in thickness and the length of the circumference of the parts (in this case about 3" or 7.5cm for a light about 1" or 2.5cm in diameter) -- two unbaked baguettes of dough. Then I wrapped the sticks around the light to make two donuts of this putty on either side of the joint. I spread the donuts against the outside of the light so that they each had about a 3/4" or 2cm band of contact with the anodizing. I made sure that no putty overlapped the joint, and that the two donuts did not touch.
Then, I temporarily imprinted the outside of the donuts with the jaws of two wrenches, using a layer of plastic bag between the putty and the faces of the wrenches. In my case, I used a pair of Knipex Cobras with the jaws spread to about 1.25" or 3cm. It would be slightly better to use a pair of crescent wrenches or very large open-end wrenches, but I didn't have them handy. The point here is to turn the outside of the donuts into giant hex-nuts or the equivalent. Take a second and make sure that you massage the putty into a shape that fills the space of the wrench's opening.
Now you have two donuts of putty that are shaped like a hex-nut (or the inside of your wrenches/pliers) on the outside, and have a broad contact-patch of connection with the anodizing on the inside.
Wait a suitable amount of time for the epoxy to set -- in my case, that meant 24 hours.
After the putty was dry, I used the Knipex pliers to loosen the two body parts. It was easy. I applied what seemed like a medium amount of pressure with a pair of 12.5cm Cobras -- the little 5" ones -- and the thread-locker gave up. And this was a joint that had frustrated all of my attempts with strap-wrenches and other devices.
Once the joint was loosened, then I removed the putty. This was a bit fiddly. I used a fine-toothed saw to cut a slot in each donut (the slot ran parallel to the long axis of the flashlight, so across the thickness of the donut). When it was close to the surface of the anodizing -- but not too close! -- I used a screwdriver with a twisting motion to break open the donut. One donut came off in big chunks, pretty quickly. The other came more slowly, and with more picking and fussing. I used my thumbnail to scrape the putty off the anodizing, and to scrape it out of the slight texturing in the ano (the texture and fluting made this donut trickier to remove, but it still all came clean). I have bizarrely tough finger-nails; if you do not, then popsicle sticks or other pieces of wood will do the job of scraping off the putty without harming the anodizing.
The only thing that was slightly tricky with the Knipex pliers -- and would be easy with crescent or open-end wrenches -- is that I wanted to apply *torque* to the putty-nuts, but not *squeeze* the putty-nuts. Squeezing them against the body tends deform the donut and cause it to break away from the body of the light. That's what you want to do after you have loosened the joint, but not while you are still attempting to loosen the joint. With the Cobras, this meant making sure that the handles were squeezed all the way together when I was imprinting the soft putty. That turns the pliers into essentially a fixed-width open-end wrench. You could not do the same thing with a pair of e.g. slip-joint pliers, where you have to bear down with a squeezing motion in order to apply torque. (You could do pretty well with a pair of large vise-grips, because you can dial out to a fixed large diameter with those, too.)
Anyhow -- it worked just as well as I had hoped. It loosened the threads that nothing else was loosening, and it did not leave any marks on the anodizing. I feel good about all of that!
This is still a method only for desperate cases. It has many drawbacks. I had to buy the putty to begin with, and that cost $5 for a non-reusable input. It was slow. In addition to the 24 hours for the putty to dry, it probably took 15 minutes for making and shaping the donuts, and 45 minutes for cleaning the ano after the joint was open (I went slow in order to avoid any possibility of scratching the ano). By comparison, the strap-wrenches are quick and simple and have no incremental cost for an additional usage. They are much more convenient, when they work.
But when they don't work, you can give this method a try.
