I just had an email conversation with a student who was giving me a progress report. Part of the discussion involved having a new bow and a newly affixed bow sight. I thought you might like to get this information, too.
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When attaching a sight block I do the following. Attach the sight block screws barely snug. Then I pull down on the sight bar so that the sight bar is in its lowest possible position (with the bow being vertical) and then I snug up the top screw, remove the bottom screw, add Loctite and screw it into place snuggly. Then I do the same with the top screw. If the block does somehow come loose, the sight is already in its lowest position, so it cannot fall any farther and minimal movement should occur. The hole is you will notice the sight coming loose before you lose points. Others cut a piece of plastic out to match the back of the mounting block and use that as a sort of “lock washer.” Both of these work quite nicely.
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Then he mentioned replacing the screws that attach the mounting block to the riser and I chipped in with:
When buying screws, the length of the shaft is critically important (unless the mounting holes are drilled and tapped all of the way through the riser, but this is rare). If you get screws that are too long, when you crank on them you will push out a bubble of aluminium on the other side of the riser! Also, you want to make sure that the base of the screw fits into the mounting block exactly. Typically these mounting block screw holes are countersunk making a kind of cone that accepts the cone-shaped bottom of the screw heads chosen to be screwed in there. Sometimes the countersink is cylindrical because they use cap screws (with barrel-shaped screw heads). I prefer the cone-shaped countersinks as they are self-centering.
Even if the screws supplied require a screw driver rather than a member of the set of Allen wrenches we all have with us, the screws are to be fixed so not to come out so who cares what kinds of heads are on them? These are not screws you need to make frequent adjustments with.
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The student also mentioned that he used electrician’s tape to prevent the mounting block from marring the finish of his new riser (very understandable) to which I responded:
Do not use electrician’s tape as it turns to plastic goo over time while under pressure. Use a piece of flexible plastic from the packaging accompanying so many products (not the brittle stuff, the tough stuff you need a kitchen knife to cut through). Trace out the mounting block on a flat sheet of the plastic and then cut out the outline using a sturdy pair of sharp scissors. Use a hole punch to remove the plastic from where the screw holes are. Tom Dorigatti wrote an entire article on making such screw lockers in Archery Focus, check it out.
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PS For those of you who are interested, I do remote coaching (via email, video, stills, etc.). If you are in need and cannot find a local coach and this might appeal to you, you can contact me at firstname.lastname@example.org.