Boyd Allen
Active member
A fellow that I have helped (just a little) with a project or two, works at a place where returns from a major hunting and fishing retailer come. Some of these returns are warranty items that are unsuitable for economical repair, and so they are discarded, including some cheap rifle scopes. I have always wanted to know more about how scopes work and are constructed, so when he told me that some are being thrown in the dumpster, I asked if he could send me a couple to take apart. He said he could, and he did. This put me back in grade school, taking something interesting apart, that I was not at all sure would not be ruined in the process, but since they were destined for the dumpster, if not now, when?
The first thing that I figured out was that I did not have the tools to do the job, so off to Harbor Freight for an eight dollar and something set of very small screwdriver bits and a handle, really very nicely done...honestly, and then to first stage disassembly.
The objective lens group had evidently been previously been taken off and put back, so that was easy, no tools required, but the occular group, adjustable by a four lead (or start) thread was retained by a single tiny slotted screw, that took some force to loosen the first time because of some sort of glue that had been used to keep it securely in place. After removing the eyepiece lenses as an assembled group, I could see the back of the erector tube, with the duplex reticule (reticle?) nearest me, and by the sides of the turrets further down, as well as the leaf spring that opposed them. I could also see how the inner tube was centered. Even though I had roughly turned the windage and elevation adjustments to their extremes and then back half way, the erector tube was visibly off center, so I made adjustmets till the gap around it seemed to be even. Later I will roll the scope on V blocks to see where this put the reticule. I should also probably mention that before I did any of this, I took one of the turrets apart to see how it worked, and was surprised that even though the scope was cheap Chinese, that it seemed to be reasonably well made and sturdy. My last move was to remove the large screw on the power selection ring, which allowed me to slide it forward revealing the slot in the main tube through it protruded to engage the lens group within the erector (inner) tube that was moved to change to change magnification. I could also see that there were four Phillips head screws that were spaced around the outer tube that probably secured the whole inner assembly. Given what I see when looking through the scope, no broken, loose or axially misaligned parts, it seems highly likely that the scope was put together incorrectly, and this next bit of taking apart may reveal the flaw. The image fills the eyepiece at nine power, but does not at three. Perhaps one of the lens groups is out of its proper position. Maybe I will be able to see some evidence of where it belongs. Perhaps I will irrevocably damage the scope trying to find out. We shall see. In any case, it is a small adventure that has the feel of things that I did when I was a lot younger.
The first thing that I figured out was that I did not have the tools to do the job, so off to Harbor Freight for an eight dollar and something set of very small screwdriver bits and a handle, really very nicely done...honestly, and then to first stage disassembly.
The objective lens group had evidently been previously been taken off and put back, so that was easy, no tools required, but the occular group, adjustable by a four lead (or start) thread was retained by a single tiny slotted screw, that took some force to loosen the first time because of some sort of glue that had been used to keep it securely in place. After removing the eyepiece lenses as an assembled group, I could see the back of the erector tube, with the duplex reticule (reticle?) nearest me, and by the sides of the turrets further down, as well as the leaf spring that opposed them. I could also see how the inner tube was centered. Even though I had roughly turned the windage and elevation adjustments to their extremes and then back half way, the erector tube was visibly off center, so I made adjustmets till the gap around it seemed to be even. Later I will roll the scope on V blocks to see where this put the reticule. I should also probably mention that before I did any of this, I took one of the turrets apart to see how it worked, and was surprised that even though the scope was cheap Chinese, that it seemed to be reasonably well made and sturdy. My last move was to remove the large screw on the power selection ring, which allowed me to slide it forward revealing the slot in the main tube through it protruded to engage the lens group within the erector (inner) tube that was moved to change to change magnification. I could also see that there were four Phillips head screws that were spaced around the outer tube that probably secured the whole inner assembly. Given what I see when looking through the scope, no broken, loose or axially misaligned parts, it seems highly likely that the scope was put together incorrectly, and this next bit of taking apart may reveal the flaw. The image fills the eyepiece at nine power, but does not at three. Perhaps one of the lens groups is out of its proper position. Maybe I will be able to see some evidence of where it belongs. Perhaps I will irrevocably damage the scope trying to find out. We shall see. In any case, it is a small adventure that has the feel of things that I did when I was a lot younger.
