helical coil insert tool

Factual Questions
1

Hello, I have a small problem, I bought a new lens for my camera, it has a threaded hole where you can attach a mounting foot to it. I bought a special aftermarket foot for this lens. The trouble is the foot will not properly engage due to the orientation of the threads. Perhaps it would be more clear if I show a imge.

As you can see in this image

http://www.nikonians.org/dcforum/User_files/3f4fec173aee307e.jpg

the start of the thread is in the 5 o’clock position. This is someone elses lens. Mine however is in the 12 o’clock position. This little thread is causing me great trouble, as my aftermarket lens foot will not lock in place becuase it gets hung on this thread.

A little rotation clockwise would fix this. However, I dont know where to get the tool to do this. I think this is called a helical coil, I am not sure. If it is, there must be a tool used to insert and remove these coil things.

The threading is a standard 1/8" tripod mount, at least I think 1’8". Is this a home depot type of tool, anyone know where I can get one.

I would love to find a local place, but will order online as well, right now, google is not playing nice, I get more about DNA than machine parts.

2

I’m pretty sure it’s a Helicoil which, by the way, is a registered trade mark. Unless you are skilled in working on such equipment, I would suggest to take it to a camera repair shop and explain your difficulty.

In my experience, once the Helicoil is seated it can’t be moved without peril of damage.

3

That is indeed a Heli-Coil thread insert.

For those watching at home, it’s a coil of square wire that is turned into some larger-diameter threads. This gives the new threaded hole a clean, smooth, and stainless-steel set of threads. In the case of this camera lens, the body is probably aluminum, and the threads fairly shallow, plus the attaching bolt (into a tripod or other mount) is installed and removed many hundreds of times over it’s lifespan.

The stainless is more wear-resistant and less prone to stripping or pulling out from overtorquing.

They were designed to repair stripped holes, in fact- you drill the hole larger, thread it with a special tap, then drive in the slightly-oversized coil into the hole. Often the repair is stronger than the original threads.

Anyway, as to your question, the coils are driven into the holes by a “key” that grabs them by a tang at the bottom of the coil- a bar that’s aligned through the center of the coil axis, like a screwdriver slot.

When the Heli-Coil is installed, the procedure is to break off the tang, which is scored for the purpose, so it doesn’t get in the way of the screw or fastner.

I can clearly see in your photo that the driving tang is gone- any attempt to drive the coil either direction is pretty much a lost cause.

However, I’ve dealt with the occasional similar problem- the coil doesn’t seat fully, and a bit of the end is sticking up. My usual move, assuming it’s just a corner, is to grind it down with a stone, sanding drum or cutoff wheel in a Dremel.

You might also try something like a thin shim of rubber, like cut from a bicycle innertube, as a non-slip gasket between the camera and the mount. A hair of space will help it clear the snag.