NikonGear'23

Gear Talk => Lens Talk => Topic started by: whatdoido on November 01, 2024, 18:11:13

Title: Micro-Nikkor 105mm f/4 AI - separating helicoids with key in place?
Post by: whatdoido on November 01, 2024, 18:11:13

I've picked up a Micro-Nikkor 105mm f/4 AI and Ive been trying to regrease the helicoids as its very dry and v gritty.  I've been able to strip it down to where I need to remove the helicoid key.

However, as Richard Haw notes the screws securing the helicoid key are very tight:  https://richardhaw.com/2017/12/31/repair-micro-nikkor-105mm-f-4-ai/

've soaked the rear of the screws with lighter fluid, IPA, acetone and also heated up the screws with a soldering iron and they just will not move - same as with the aperture activation rod.  As I stare down the barrel I can see the helicoid key sync'ing movement of the central/focus helicoid that in turn drives the inner/front helicoid.

Now, the question is:  if I continue to turn the focus helicoid at some point it will disengage from the helicoid key and I _should_ be able to free both the helicoids.  Now, before I ruin this lens, is this a sensible approach?  Will I be able to reattach/mate the helicoids (front/inner to the central) and then be able to line up against the in place helicoid key?

thanks

Title: Re: Micro-Nikkor 105mm f/4 AI - separating helicoids with key in place?
Post by: whatdoido on November 09, 2024, 15:01:45

FWIW, i decided that there would be too many variables to contend when remating when separating with the key stil in place.

To sovle/workaround for my gritty and sticky helicoids, I ended up applying a lot of lighter fluid and extending / collapsing the helcioids the best i could - this seemed to flush the bits of dried grease and lumps enough that felt much better - added some new grease to the exposed helicoids and its much better.  but i;d say this is last resort