400 mm stuck on body

[tony_cunningham]

I have a 400 mm lens (outer bayonet threaded mount) jammed on a P67

body. Any ideas? I am almost certain it is not cross threaded. How

about trying one of those vehicle oil filter removers? I don't think

they are big enough diameter to pass over the body of the lens

though. The lens is in near perfect condition, so I don't want to

damage the ring if at all possible. I mounted the lens at around

freezing and am trying to remove it at room temperature, but I have

done that many times before without problems.

[WJT]

The ring is aluminium (I think) so it should heat up faster than the body. How about using a hair dryer on hot to warm the ring up and expand it. The oil filter wrench sounds like a good idea; they come in all kinds of styles and sizes. The wrench and some rubber strips (from a bicycle innertube or such) to protect the lens might work. I ran into a severe lock-up like this also, but it eventually came free on its own. Good luck.

[steve_rasmussen]

Occasionally, the outer bay lenses will do this but not to the degree yours has. I would suggest using two people to try to unscrew it( one person holding the rear area of the lens and the other with both hands on the ring). It this fails, try a penetrating spray but make sure you use the tube applicator so that the light lube goes where you want it. The ring can be completely removed from the lens, for cleaning up the light lube afterwards.

[bert_wiklund]

I think you are up to a new ring. I haven't had your problem. But

problems on the contrary, the ring passed last thread and

couldn't hold the lens to the body. I don't remember the price, but

it wasn't expencive. Do use full force!!

[tony_cunningham]

Many thanks for your responses. I have only just solved the problem by purchasing an adjustable (60-110 mm) chain wrench for removing oil filters. I removed the tripod mount to allow enough space for the chain and placed two layers of rubber sheeting over the threaded ring to protect it. It still took considerable effort to remove it. The chain penetrated the rubber and scored the surface of the ring at one point, but nothing serious.

 

I tried a hair dryer, then moved up to an electric paint stripper used carefully, but heating did not work. I did not dare use oil, although it would have been the next stage if the wrench had not worked.