Repairing a spotting scope

[East_TN_Patriot]

I received a nice spotting scope from a buddy of mine and I am trying to figure out how to fix it. It has an aluminum body and is attached to the mounting bracket with a threaded knob that screws into a threaded hole in the body of the scope. Problem is, the threaded hole is totally stripped out (big shocker when you build your scope to utilize a steel screw in a soft aluminum hole, but I digress). Basically, when I try to screw the knob into the hole, there's nothing left for the screw to grab onto. Any ideas on how I can fix this?

[Jonnin]

cut a new hole in a larger sized screw/bolt with a tap? And next time, be very careful to not overtighten it etc, and maybe use soft bolts (brass? Al? etc?) instead of steel, if possible?

You may have to make a new knob if you care about that. Easy to do that too: cut the head off a bolt and tap a knob of wood, metal, plastic, etc. Fill the thing full of glue and thread into the knob, let it harden, then its good to go as a new knob/screw setup.

If you do not have the tap, find someone who does if you do not do this sort of thing often. If you use steel into softer materials, a screw will cut into the material so drill it out to just a bit smaller than the threads, then screw it in, and LEAVE IT IN, that will work without a tap but its not going to last if you take it off and on a lot. If you leave it where it is, thats fine. If you take it off and on, you want a bolt with fine threads that go in clean, and will want to use the tap, that will last longer.

You can also "rig" it by doing something like filling the hole with jb-weld or similar compounds, and cut into that so the original bolt/screw thing will work. This will hold pretty well if not abused.

[East_TN_Patriot]

Thanks for those ideas. I was also sitting here thinking about it and I may try to widen the hole a lot, fit a steel nut into the hole, and secure that with either JB Weld or epoxy.

[Jonnin]

That will work, but if you tighten it too hard you can pull the nut out of the compound and have to start over with the annoying task of getting the old, cracked JB out. Its similar to what I was getting at, but more destructive as it makes a much larger hole than required. Given the small size of the bolts involved, and the strength of the JB stuff, your idea should work very well.

[Guest Lester Weevils]

Speaking from relative ignorance-- The standard thread size for cameras and small scope tripods is 1/4" - 20. It would be very desirable to stay with the standard thread size.

I think I saw in an auto parts store steel inserts that have an inside thread and outside thread. Drill out a hole in the scope and tap for the outside thread, then screw in the insert (with some thread lock compound)?

If it can be avoided you don't want metal flakes inside the scope. So unless the mounting foot can be removed from the scope body, you would either need a "blind tap" and not drill all the way thru the body. Or dissasemble the scope, drill thru and tap and blow out all the metal chips, then reassemble.

Oil is painful to remove fully from coated lenses. Try to keep lube well away from the lenses. Sometimes some light oils can creep over time, so some oil a few inches away from the lens can eventually find its way to the glass.

[Guest Lester Weevils]

accidental double-post

Edited March 25, 2011 by Lester Weevils

[VERO1]

Do they still sell helicoils? Basically they were threaded inserts you screwed into stripped out holes.

[Guest Lester Weevils]

On dissasembling the scope-- Sometimes the inexpensive scopes use screws on the lens cells but they also put double-sided thin sticky tape in there. If there is double-sided sticky tape, then it can be very difficult to disassemble without destroying the gadget.

[lowery100]

++ TIME-SERT Threaded inserts for stripped threads, threaded inserts, thread repair stripped sparkplug's, Ford sparkplug blowouts, threaded inserts threaded, repair stripped threads, stripped threads, inserts threaded inserts, Ford spark plug repair, These are similar to Helicoil but work a little better. They are a little pricey for a single use though.

[Jonnin]

Cool, I didnt know you could get that for a small sized project, I have used the big ones before.

[VERO1]

You may have to resort to the heavy duty fixes, duct tape or drywall screws!

[East_TN_Patriot]

You may have to resort to the heavy duty fixes, duct tape or drywall screws!

I think I'd need some WD-40 in there too if I go that route.