Grease for helicoid

ilguercio · Posted: Mon Oct 01, 2012 10:17 pm Post subject: Grease for helicoid

Hello, i have an 85 mm lens from Samyang and its focusing action is quite stiff at times. It depends on the direction the lens is facing, sometimes it can also be silky smooth.
So, i want to grease the helicoid again and i read that a teflon grease is a must here.
Now, i do have a tube of ptfe grease which i use for many of the working tools i have in my home and i guess i can use that for the helicoid. Am i right?

Orio · Expire: 2012-12-04

It is important that it does not get too fluid with heat.

ilguercio · Posted: Mon Oct 01, 2012 10:32 pm Post subject:

Orio · Expire: 2012-12-04

ilguercio · Posted: Mon Oct 01, 2012 11:02 pm Post subject:

Nice, it shouldn't be too difficult then. At least i have disassembly pictures of the procedure somewhere online.
http://www.flickr.com/photos/gigel/sets/72157626746203425/detail/

ForenSeil · Joined: 15 Apr 2011 Posts: 2726 Location: Kiel, Germany.

Attila · Expire: 2025-11-18

To select perfect grease is not easy, best if you can find a shop with large scale of choices and prepare your self , not cheap.

Repair man who fix stuff to me selected a grease , which cost is 300 EUR /kg , if you are lucky shop sell not only in kg pack Smile

Lloydy · Expire: 2022-01-01

I've had some good results from a silicone lube, but I have no idea of what the specification is. All I know is that it is intended to lube the mechanical parts of electrical contacts and that it is thicker than something like an oil used for sewing machines - a light oil, and thinner than a light grease such as used for bicycle cranks and hubs.

ForenSeil · Joined: 15 Apr 2011 Posts: 2726 Location: Kiel, Germany.

I've already posted it in another thread but for the search-function it might be senseful to repost it here again:
http://forum.mflenses.com/anyone-skilled-in-rheology-t53245.html

Quote:
I'm using this ball bearing lubricant ("Hanseline Kugellager Abschmierfett") which works imho almost perfectly (useful viscosity, not volatile, long durability, not very temperature sensitive, very cheap (less than 2€ per 50g here)). According to the description from the producer it's made for temperatures between -30°C to +60°C, which would also fit for helicoids. I have it from a local store but you can also buy it from Ebay and several online stores at the moment.

It's based on a lithium stearate and it has "consistency class 2", so it should theoretically stiffer than most vaselines
I'm sure there are better ones, but it's cheap, reliable, safe and works much better than vaseline/silicone oil/oil for bycicle chains and other standart over-the-counter lubricants

Bye the way, I think that different lenses need different visosities for their lubricant. For example an old Elmar 50/3.5 has an very chunky helicoid while the Hexanon has a pretty filigree weird double-helicoid - I guess the Elmar would prefer a medium or even pretty stiff lubricant while the Hexanon would prefer a very smooth lubricant etc.. I already tried to relubricate the Hexanon with vaseline and it stayed pretty stiff, while viscosity-wise vaseline worked ok for most other lenses I relubricated before.

ilguercio · Posted: Wed Oct 24, 2012 11:28 pm Post subject:

And i eventually did it.
The fact is that this lens doesn't focus around a helicoid but there is the focus ring and the barrel and no helix in behind.
So these two pieces simply revolve one on another in the simplest way. Now the focus is much smoother. I also put a tiny bit of grease between the internal barrel and the back glass group as well, just to make things flow better. I obviously did a bit of focusing before reassembling the lens just to clean the excess grease.
So, the procedure is not difficult and it took me an hour as i didn't mark the alignments and thus forcing me to make a bit of trial and error. If you need further explanations just ask. The grease seems to be good, it has an operating temperature of -25°C/+120°C so it should cope with the most furious focusing actions.