Separating misthreaded filter

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EverLearning
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p.1 #1 · Separating misthreaded filter

Hi all. I have a B+W step up ring (72-77) and a 77mm cokin filter ring that some how got cross threaded. I think that is the term. It is not screwed on straight, but rather is screwed on at an angle. I can't get them to budge.

I have tried using elastic bands and rubber 'gloves' to grip it and turn, but to no avail. Any suggestions on how I can get these apart without ruining either?

Thanks in advance!

Aug 07, 2008 at 01:14 AM

Genes Home
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p.1 #2 · Separating misthreaded filter

You are lucky you didn't have this happen on the nose of your lens.

You are going to ruin at least one, and there's a 99% probability you will ruin both.

The only way both won't be ruined is if one of them is a much harder material than the other, and can thus "cut" it's way off. Otherwise both sets of threads are doomed.

See if you can find a couple sets of those big pipe wrenches that HAVE THE RUBBER LOOP material instead of metal jaws. Sears and Home Depot sell them, You should be able to "test" a pair in the store to see if they will give you enough purchase to spin the filters loose.

Work some "break free" or light machine oil into the threads, and that may help as well.

Good Luck!

Aug 07, 2008 at 03:04 AM

Cableaddict
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p.1 #3 · Separating misthreaded filter

If one is thicker than the other, or (unlikely) if one is made out of a different plastic compound than the other, you may have success with either extreme heat or extreme cold. -The idea being that one would expand or contract more than the other.

Obviously, you'd need to figure out how to apply the heat / cold to just the plastic. Don't put the whole lens in an oven. Maybe a hair dryer aimed sideways? For the cold, maybe a flat piece of dry ice applied directly?

I'd also spray some kind of industial lube in there, as Geno mentions. Something really thin, like the above-mentioned "break free" or Tri-Flow. In fact, I'd try the lube first, with no heat/cold. Try-Flow stuff is amazing. "Break free" CL-5 is also really good stuff, but I think Tri-flow is a tad thinner. You may need all the penetration you can get.

Either one, though, but I don't recommend machine oil. It's too thick & won't penetrate as well. I've experimented with lots of lubricants (ahem) and Tri-Flow is far & away the best non-corrosive spray for tight, stuck parts.

I'm not so sure about using those "rubber loop" wrenches. I first thought to agree with Genes for that idea. Those wrenches do give a lot of power and a good grip. However, they don't really apply even pressure all around. Most of the pressure is on the leading edge, due to the band being pliable. You might be better able to keep even pressure with your hand. Hard to say.

Good luck.

Edited on Aug 07, 2008 at 10:41 AM

Aug 07, 2008 at 07:18 AM

Mike V
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p.1 #4 · Separating misthreaded filter

Zyliss Strong Boy.

It's a type of jar opener available from a kitchenware shop.

Very similar to a strap wrench, but a bit more delicate.

You might need two of them if the filters are really stuck.

Aug 07, 2008 at 11:08 AM

EverLearning
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p.1 #5 · Separating misthreaded filter

Thanks for the replies everybody. Just to clarify a couple of things. No lens is involved here; not even any glass. The first ring is a B+W step up ring (72mm to 77mm). These rings are brass and are not supposed to bind (if you thread them correctly, anyway). The second ring is a 77mm Cokin ring for a P series filter holder. It appears to be plastic.

I hope that clarifies and perhaps generates a few more ideas. I will try putting the rings in the freezer in hopes that the brass will contract enough to get them apart. If not, I will try a lubricating agent. If that doesn't work and there are no more ideas, I guess I will try breaking the plastic Cokin ring; it is much cheaper and should be far easier to break.

Thanks

Aug 07, 2008 at 03:13 PM

jhom
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p.1 #6 · Separating misthreaded filter

Have you tried using a small jeweler's screw driver? If you can leverage one of the rings, you can possibly correct the crossthreading. Be gentle and patient.

Jim

Aug 07, 2008 at 05:44 PM


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