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Tapping the holes in the rear OTA housing
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| Here is how I did it without getting filings inside the scope. Pay close attention and you should have no problems. 1) Pull ONE plastic plug out and save for a rainy day in your box of extra & removed pieces from your LX 50. 2) Tip the scope so the corrector faces the ceiling (this IS important). Do Not reposition the OTA until the holes have both been cleaned out with the vacuum (step #6). 3) Put some thick oil on the tap (I used Phil Wood Tenacious Oil (a bicycle shop thing, also used on wheel chairs) it is about as thick as 90W gear lube as used on a car, but doesn't smell nearly as bad). 30W engine oil will suffice, I would avoid grease because it will be harder to clean out of the holes. 4) Run the tap in about 3 turns or so. Back the tap out and clean it off with solvent or thinner. If you have never tapped anything, please find someone who has used a tap & die set before! The last thing we need is a tap broken off in the back of the telescope housing, and the smaller the tap the easier they break! Your public library will likely have books on machine shop practices. Most automotive technicians have a tap & die set and usually know how to use it correctly. 5) Re lubricate the tap and turn it in another 3 turns or so. At this point the threads should be all the way cut (tap will turn easier). Back out the tap and clean it off. 6) Uncork the eyepiece hole. Place a shop vacuum against the hole you just tapped and suck air through the scope through the hole you tapped. This will pull any chips left through the hole and into the shop vacuum. Any chips that fell off the tap inside should be sitting next to the hole, so the vacuum should get them. (This is why the corrector faces the ceiling.) It is unlikely you can pull enough vacuum on the OTA to hurt anything, but let's not get carried away! 7) Repeat the above for the other hole. DO NOT TAP BOTH HOLES AT THE SAME TIME!! Putting the vacuum against the first hole to clean it could pull chips from the second hole farther into the scope!!! Do one to completion and THEN do the other. 8) Take a Q tip and some rubbing alcohol to the hole as best you can to cut the oil film. A toothpick and thin cloth can be used with the alcohol to clean the threads of lubricant. 9) Repeat steps 1 through 8 |