Maximize your profit: making target knobs for a scope: a pair of custom-made target knobs can be a simple and profitable add-on to a scope-installation job.
A recent project is a good example: Some rifle scopes lack a simple and effective way to adjust the elevation and windage. The time-tested coin-slot adjustment screw isn't bad--if the shooter happens to have the right size coin in his pocket. In my experience, the raised bar we see across some scope knobs is a poor excuse for an adjuster. Where the adjusting detents on a knob resist easy turning, this form of adjuster is hard to turn between the tips of your fingers, and there's no tool made to fit them.
For these reasons, a customer recently asked me to make a pair of knurled brass knobs for a scope he brought into my shop. "Can you do it?" he asked. I told him the materials cost was next to nothing, and the labor shouldn't take more than an hour or so. The project was a go from that point on.
The original bars on these scope knobs measured 0.2 x 0.420 inch and were raised above the round base by a mere 0.1 inch. The part was attached to the reticle adjustment base by a pair of fine-threaded screws spaced 1/4 inch apart. These two laterally opposing holes and screws would be reused to attach the new adjusting knobs. The countersunk screws would pass directly through the new adjusting knob. Making the knobs was a straight-forward job on the lathe.
First I chucked a piece of 5/8-inch brass rod in the lathe with an inch and a half extending beyond the chuck. I cleaned the piece up to a 0.60-inch diameter and knurled about an inch of it. From there, I turned a tenth of an inch of the shaft down to the diameter of the replaced part, which was 0.420 inch. Then I used a cutoff tool to cut the piece from the stock to a length of 0.20 inch. The edges of the knurled part of the knob were rounded using a flat file before final cutoff. To make the second knob, I duplicated this operation while the shaft was still in the lathe.
Next, I marked the screw-hole positions on the undersides of the knobs with a fine-point marker through the holes of the old knobs. A starter drill was then used to precisely start the holes. The four holes were then drilled at screw size through the knobs. The screw holes were then countersunk to allow freedom for the screw heads at a depth that allowed about 0.085 inch of screw thread to extend through the holes without bottoming out.
Finally, I used the existing Phillips-head screws to attach the target knobs. The slightly raised knobs still permitted the original knob covers to be used. Adjusting the knobs for windage and elevation was now easy and convenient with the thumb and forefinger. The adjustment increments were more easily felt with the new knobs, and the markings that indicate the knob positions were still easily read. Job done--in less than an hour.
Target-type knobs were not available for this particular scope, and the original ones were not working well. But making a pair of replacement knobs was a very practical project. The original screws were conveniently reused to attach the new parts, and the original caps were high enough to cover the new knobs. The customer was delighted with the results, and very happy to pay my minimum one-hour shop rate.
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|Author:||Johnson, Norman E.|
|Date:||Feb 1, 2009|
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