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Looking for thicker grease for helicoid in Minolta 135/2.8
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PostPosted: Sat Oct 20, 2018 1:46 pm    Post subject: Looking for thicker grease for helicoid in Minolta 135/2.8 Reply with quote

I got this Minolta MC-X 135/2.8 that had a bad motion in the focusing threads.

I cleaned out the old gray/brown grease and regreased it with Helimax XP. But it is too thin. I get play in the threads so I need a thicker grease that fills the thread gap better.

Anyone here that can recommend a grease that is thick that preferably is available in Europe (all the ones outside EU comes with such a high customs charge with the VAT and administrative charges on top)?

Thanks and best regards from Sweden! / Anders







PostPosted: Tue Jan 19, 2021 10:55 pm    Post subject: Reply with quote

I've been using the 33B from Losimol on my MC-X 1.2/58mm and MC-X 1.7/85mm as well as on my MD-II 1.2/50mm lenses. It's quite a "light" grease, but works perfectly on these lenses. Other thicker greases by Losimol would be 3345 and 3346.


PostPosted: Wed Jan 20, 2021 5:43 am    Post subject: Reply with quote

Good day you could try this is denser than Helimax XP: Grease, Helical # 30 (Medium) 8ml and you can find it here without customs duties:

PostPosted: Mon Nov 29, 2021 9:20 pm    Post subject: Reply with quote

Replying a bit late in the day here (new member).

I have a number of these Minolta 135mm Rokkors as well and Helimax-XP has always worked fine for me. Helimax-XP is already thicker than the original moly-loaded grease that Minolta used.

Judging from your photos I would suggest that there is not nearly enough grease in the helicoid, I can see loads of dry spots.

I tend to liberally and fully load the helicoid (both the alu and brass threads) with Helimax-XP making sure there are no dry spots. Then I wipe off the excess that collects at the ends of the alu threads after having worked the parts back and forth a few times over the full length of the helicoid. What you are looking for with a helicoid like this is that the space between the male and female threads is fully packed with grease at all times over the full focussing range. Rheology takes care of the consistent and right amount of grease migrating through and between the threads as you focus, therefore once the excess at the ends has been wiped off, no new excess should be building up there. (This only works though if all old grease has been removed, very thoroughly, otherwise you end up with new grease floating over old oil/dry lub).

Don't be fooled by what appears to be the small amount of grease Minolta originally applied. All you will see left on an old helicoid like this is the remaining dry constituents of the original grease (likely lithium stearate thickener & molybdenum disulfide dry lubricant). Most if not all of the base oil(s) of the original grease would have migrated to other parts of the lens by now by capillary action/evaporation/condensation.

I have used this method on 150+ Rokkor lenses so far, with no problems. If anything, I would say that Helimax-XP can be just a bit on the thick side for some of them.

PostPosted: Wed Dec 01, 2021 2:23 pm    Post subject: Reply with quote

If NLGI ratings are a thing over there try any grade 2 grease.

PostPosted: Wed Dec 01, 2021 3:22 pm    Post subject: Reply with quote

I concur that NLGI grade 2 should work, I have used that in the past on these lenses before I discovered the Helimax-XP grease and the S-10 S-30 etc. greases from Japan Hobby Tools (since removed and replaced with Helimax-XP)

But it will be noticeably stiffer to focus.

Word of caution: sometimes "white lithium grease" is mentioned as an alternative. AFAIK that doesn't really mean anything more than that the grease uses a lithium stearate thickener has a white appearance, so no way of telling whether it is any good for helicoids. Then beware that some white lithium greases use titanium dioxide as a dry lubricant additive (albeit an allegedly less abrasive form of it). That may be non-abrasive in context of use in hardened steel bearings, but in my experience it is still far too abrasive for use with aluminium helicoids. I once tried this as an experiment with a white lithium grease known to have a titanium dioxide dry-lube (Weldtite white lithium grease, designed for use in bicycle bearings, with the stated "non-abrasive" form of titanium dioxide dry-lube). Applied to a perfectly cleaned aluminium helicoid withins several full focus throws I could see the grease turn from white to grey and continue to darken as the helicoid was exercised more, which indicated the grease was abrading the aluminium oxide layer quite rapidly.

Not all white lithium greases will be like that, and if they have a milky white appearance due to e.g. a Teflon dry-lube additive, that should be fine.

Also, try to look for a grease with a synthetic base oil rather than an organic petroleum base oil (e.g. look for one with a PAO or Polyalphaolefin base oil).

For reduced oil separation over time, it would be interesting to see if anyone has ever experimented with a more stable grease with a polyurea thickener instead of a lithium stearate thickener for helicoids. The obvious drawback is that then you can't use a lithium grease anywhere else in the lens as the two generally are chemically quite incompatible

PostPosted: Thu Dec 02, 2021 6:02 am    Post subject: Reply with quote

RokkorDoctor wrote:
. . .
I tend to liberally and fully load the helicoid (both the alu and brass threads) with Helimax-XP making sure there are no dry spots. . .

Is that a personal preference regarding focus damping feel, or is it to prevent possible damage to the helicoid?
More than once I've read re-lubrication advice suggesting a sparse amount of grease is sufficient to keep helicoids functioning.

PostPosted: Thu Dec 02, 2021 1:47 pm    Post subject: Reply with quote

55 wrote:

Is that a personal preference regarding focus damping feel, or is it to prevent possible damage to the helicoid?
More than once I've read re-lubrication advice suggesting a sparse amount of grease is sufficient to keep helicoids functioning.

Partially a personal preference, partially based on engineering grounds:

Grease in the helicoid serves four main purposes:

1. as a lubricant for the helicoid
2. as a rotational/mechanical dampening medium
3. as transversal/longitudinal optical stabilisation medium for the helicoid (i.e. remove play)
4. as a corrosion inhibitor

What type of grease and how much of it is required depends on the helicoid under consideration. A sparse amount of grease is usually enough for lubrication, but even with a thick grease may not be enough for removing the play.

Helicoids are a precision focussing aid, and any play in them is detrimental to performance. Helicoids of this era were manufactured with a mechanical clearance significantly greater than the required focussing accuracy, both given the affordable mass production machining tolerances at the time and in order to allow for the different rates of thermal expansion in the materials used, to prevent them ever binding in extreme heat/cold. As such, they were originally designed to have full grease contact between the two helicoid threads, in order to take up the slack and achieve the required ca. 10 microns mechanical stability. Indeed, several more recent Rokkor lenses that I serviced years ago for various reasons other than focussing issues, still had the fairly fresh factory-applied grease in the helicoid, which showed them to be fully and liberally lubricated.

The use of that amount of grease is not without its drawbacks, as we all know (oil separation & migration over time).

It is a bit of a personal preference as to how to re-grease the helicoids now, depending on desired focus stiffness, focus accuracy, resistance to oil separation etc. This is especially relevant where long term use of an old dry helicoid may have imparted significant wear on the threads resulting in increased play. The amount of grease required to take up the play between the helicoid parts of a factory-fresh helicoid can be significantly less than that required to do the same for a worn one.

I take a lot of very shallow DOF photos, so for me focus accuracy is the dominant criterion. Thus I ensure grease contact over the full surface area where the two helicoid threads meet as per the original design. The easiest way to do that is to apply too much grease, work it over the full threads by several full operations of the helicoid (at least 10 full travels back and forth, and wiping away the excess every time until no more excess grease builds up at the ends.) If that means that in another 30 years I may have to clean & re-grease it again, so be it; in the mean time the lens will suit my needs.

However, if longer-term resistance to oil separation is more important to you, a smaller amount of thicker grease may work for you. I tried that myself but found that the helicoid then had a tendency to push the grease around more leading to uneven focus resistance and unpredictable play, so I stuck with the method that works for me. Whatever method you choose, all old grease will need to be removed thoroughly first, the new grease will need to make very good direct contact with the underlying metal.

But that's the beauty of this hobby; a lot of these Rokkors are cheap lenses with no rarity value and if you don't mind spending a bit of time on it, a great opportuntiy to try different methods and find out what works for you! Wink

A full grease film has the added advantage of restoring its original purpose as a corrosion inhibitor as well as a lubricator. I have seen many older Rokkor lenses where the helicoid had run either completely or partially "dry" and the brass female part of the helicoid in particular showed significant signs of corrosion in the threads (where the thread surfaces meet it tends to abrade away, but it collects in the deeper flat parts of the groove). Dissimilar metals in contact (brass and aluminium alloy in this case, far from the worst case fortunately) will lead to electrochemical corrosion, which a thin continuous grease or oil film will inhibit.

Incidentally, later "Rokkor" helicoids (e.g. some of the MD III 50mm and 35mm lenses) had the male part of the helicoid injection-moulded from glass-fibre filled polycarbonate, and the female part machined from aluminium (and others became alu/alu). Machining tolerances are a bit tighter there, and corrosion a non-issue. But once the oil has separated out, these later helicoids do feel a bit rougher.

That's one myth really IMHO, that the older brass/alu helicods give smoother focussing. That difference only exists once the helicoids have run (too) dry; when properly greased both older and later Rokkor helicoids are equally smooth. The alleged light and silky-smooth focussing of the older Rokkors mostly means the helicoid is dry, with just a dry film of lithium stearate soap and molybdenum disulfide remaining, which is a very "slippy" dry substance. The brass helps here as it is a naturally "slippy" metal that is more resistant to galling/fretting in dry contact with other metals. You'll find though that, whilst very smooth, the dry focussing helicoid on these older Rokkors can exhibit significant play/rattle).

The reality is that the perfect grease we are all looking for doesn't exist. By nature of what a grease is, a single base oil or mix of base oils suspended in a thickener (+ optional dry-lube and other additives like corrosion inhibitors etc.), oil separation will happen, it is just matter of time dependent on the oils and thickeners used. Very thick greases indeed tend to be more resistant to this, but they are far too thick for use in a helicoid. Never mix two greases with incompatible thickeners though, that's a recipe for grease disintegration and/or hardening!

PostPosted: Fri Dec 03, 2021 1:49 am    Post subject: Reply with quote

RokkorDoctor wrote:

Partially a personal preference, partially based on engineering grounds:
. . .

Thank you for the thorough reply, Mark!

I also use Helimax-XP grease, although I've usually been conservative with the amount. Going forward, I'll keep your thoughts in mind.