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Eclair ACL, sintered bronze bushes lubrication....


Gregg MacPherson

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The ACL uses many sintered bronze bushes in the movement block. They were, when manufactured, impregnated with lubricant that replenishes the bearing surface while the camera runs. There has been some concern and speculation on the lubricant's function with age. ACLs are about 40 years old, so some questions arise...

In spite of advise in the user manual to never add oil, it's pretty certain that many people have been randomly trying to flood oil into the juncture between shaft and bush. Coupled with the potential for aged oil remaining in the pores, it seems unlikely that this ad hoc flooding approach is replenishing the bush. I speculate that it could allow a shallow region of aged oil to develop near the bearing surface of the bush, blocking the pores.

Please, at any point, a few words from the wise will educate us all...

There is one tech, Nathan Milford, who was doing intensive Aaton rebuilds, re-impregnating the sintered aluminum bushes under vacuum. I finally found an initial link to his posts on that...third post down..
https://cinematography.com/index.php?/forums/topic/7988-buying-an-aaton-ltr-7-super16/#comment-61048

Somewhere there are other posts of his that describe in detail his vacuum process, and more. If you find that, please notify...He last visited the forum on 2010, his website's still there, so maybe he could be invited in to comment...

Nathan seems to say that the Aaton porous aluminum bushes may run dry after 4 years. I don't make any assumptions about the sintered bronze ACL bushes from that. All the anecdotal evidence suggest a much longer timespan. But it's all interesting.

Questions that arise for the ACL..

Can oil be added externally to the juncture between shaft/bush? If so, how much, how often, under what circumstances...and what specific oil. Though almost any ad hoc procedure may give some short term lubrication, can some problems arrise in the future? Some clear protocols might be useful.

Is it possible to re-impregnate the bushes? What are the methods? Can it be done leaving the bushes in situ? 

 

Pasting some useful content from the Technicians Who Service ACLs thread...

On 4/8/2022 at 7:33 PM, Dom Jaeger.....

"Sintered bearings will dry out over decades. I don’t think just adding oil would necessarily be detrimental, but yeah it isn’t the correct way to lubricate them.

Here’s an interesting discussion on ways to relubricate sintered bearings:
https://www.lencoheaven.net/forum/index.php?topic=24899.0   "


On 4/8/2022 at 09:23 PM, Gregg MacPherson...

.....Good condensed read on re-impregnation methods.

A simple infusion might work. Put the bearing in a small bag with two sealed tubes coming out. An exit path (with a tap) for the vacuum and an inlet path for the oil. A layer of fabric in there so that air and oil can move between the tube entry points and the bearing. Apply full vacuum, immerse other tube end in oil and remove plug. oil will migrate into the vacuum. I assumed this might be one of the ways it was done. Infusion is used a lot now with composites (carbon/epoxy etc) and some practical things can port from that field.

I wonder if bushes could be left in their housings, cleaned and re-impregnated in situ like that. Just thinking aloud.

I have tried oil re-impregnating the porous iron plain bearings for the feed rollers in an old wood working machine I have. I found a target temperature online, preheated the bearings and oil, watched oil sweat out of the bearing, then immersed them. I thought that by preheating the bearing I might remove some old oil, and as the temperature dropped oil would be sucked into the pores.

Gregg

There's other content on the issue on the same page, but mostly it's summarised by me above..  

Edited by Gregg MacPherson
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I think the biggest issue so far is that there is no clear info of what exact oil was used on the bushings originally and what would be a good enough modern replacement for that oil.

It is mind blowing that this kind of critical information cannot be found anywhere. I have had similar issue with Cinema Products cameras, even the bearing manufacturer does not identify clearly what kind of oil is recommended for their products other than the extremely vague "use sae30 oil" info on their page. But what kind of sae30 oil? Can any motor oil be used and if so, synthetic or mineral and what restrictions there is? Does it even matter what the exact oil type is if even the bearing manufacturer does not care at all? 

If you need to always take the old oil out first, then it would make sense that the exact oil type would not be critical as long as the viscosity is about correct for the application. The camera cla is so rare and specific work that there is lots of myths about it and it is possible that the sintered bushings oil stuff is one of them too

Edited by aapo lettinen
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Sintered bronze bearings were also known as "Oilite" bearings. My understanding was a special oil was required and the wrong oil would clog the microspaces and the bearing would wear. I too have not been able to find any particular info but it has been awhile since I searched. Makes and maintainers of analogue aircraft instruments might have a clue. There may be some light fractions in the correct oil which gas off over time as the recommended service interval for the CP was six months, whether used or not.

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ISOFLEX PDB 38 CX 2000 is a homogeneous impregnating fluid for sintered-metal sliding bearings consisting of ester oil, mineral oil and lithium soap. It is resistant to ageing and oxidation, offers good corrosion protection and can be used at low temperatures.

 

 

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It would be interesting to know how these bearings should feel like "out of factory". As I mentioned in an another thread, I have new old stock "claw control spindle assemblies". If someone has the knowledge how to take one apart and put back together, we could orchestrate an effort to get one reimpregnated and see if there's a difference in the force required for turning it.

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26 minutes ago, Heikki Repo said:

It would be interesting to know how these bearings should feel like "out of factory". As I mentioned in an another thread, I have new old stock "claw control spindle assemblies". If someone has the knowledge how to take one apart and put back together, we could orchestrate an effort to get one reimpregnated and see if there's a difference in the force required for turning it.

The simple syringe method for vacuum impregnation sounded easy enough to do for someone to test it by themself. 

All types of bushings are available new, too. Should be possible to find a new replacement for the old bushing or at least precision machine the closest alternative to fit the camera 

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26 minutes ago, aapo lettinen said:

The simple syringe method for vacuum impregnation sounded easy enough to do for someone to test it by themself. 

All types of bushings are available new, too. ...or at least precision machine the closest alternative to fit the camera 

From the graph showing oil content vs time, comparing the vacuum and hot immersion method in the page referred to by Dom above...

Looks like the vacuum method gets about 100% and the immersion method get about 90%, so immersion sounds fine, just took 20 hours at 65-80degC vs 4 hours vacuum. Their vacuum would have been (guessing) full vacuum. The syringe, should be less vacuum. Vacuum pumps that pull close to total vacuum have been around for ages. I have one we used for composites. Actually, even an old fridge pump would be ok, they can pull quite a high vacuum.

If the existing bushes are not worn i would be keen on trying to leave them in place, cleaning and re-impregnating in situ, which may be easy in a vac bag (infusion).  Pressing bearings out, new ones in, or worse, having to resize the bushes, I'm not keen. Maybe if I had a wreck to test on I might be OK.

 

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10 hours ago, Gregg MacPherson said:

From the graph showing oil content vs time, comparing the vacuum and hot immersion method in the page referred to by Dom above...

Looks like the vacuum method gets about 100% and the immersion method get about 90%,

Sorry, if you haven't seen that short paper that's not clear....100% and 90% were just reffering to the oil saturation level.

@ Simon W. This is the thread where your insights about sintered bronze bushes should go..

Gregg.

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Simon Wyss posted this yesterday on The Technicians Who Service ACLs thread....

 

Re. oillite bearings. These are typical of the years from 1958 up in camera mechanisms, the sell-and-forget mentality. A movie camera differs from household apparatus in that it must work in the cold as well as in the heat, more like a car. Do we have oillite bearings with cars? Not in the crucial places

I’d try to install a felt wick oil system, if a customer wants it. A felt lining of the surrounding area would swallow excessive oil. Two or three bores would need to be made to some parts as oil inlets. The alternative is service at regular intervals. The main problem of camera maintenance TODAY is that the cams only rarely see dozens and dozens of rolls run through them. In my experience those who scream the loudest for perfect lubrication expose three hundred-footers, then stop filming.

As important as the lubrication of shafts in plain bearings is that of gears. Most camera manufacturers have never spent a thought to how gears could be well smeared. Often burrs are present on the tooth flanks prohibiting a good oil trail.

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18 hours ago, aapo lettinen said:

even the bearing manufacturer does not identify clearly what kind of oil is recommended for their products other than the extremely vague "use sae30 oil" info on their page. But what kind of sae30 oil? Can any motor oil be used and if so, synthetic or mineral and what restrictions there is? Does it even matter what the exact oil type is if even the bearing manufacturer does not care at all? 

Keep in mind that when a lot of these things were in service, SAE 30 oil was just "motor oil" and there weren't all these choices.  It was used in engines, in little pump cans for squirting into oiling tubes and holes, for making door hinges less squeaky, for just about anything.  In many cases that really does mean it doesn't much matter.  Oilite bushings are pretty crude old-school technology; I think any light oil would impregnate the bushing and work for a decade or two.

The only time I ever ran into a problem using modern oils in place of SAE 30 was in the dashpots of the SU carbs of my TR4 decades ago when I drove one.  The performance was predicated on the way SAE 30 changed with temperature, and it got very wacky when I used 10W30 instead.

Duncan

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  • 1 month later...

Heikki brought up some ideas from Bernie O. in the Techs Who Service ACLs thread. I'll just quote Bernie here...you can link to the source from Heiki's post. I couldn't master that quick enough.

On 9/23/2006 at 2:23 AM, Bernie Doherty said:

"...Eclair installed "self-lubricating" bearings in all of their cameras, which theoretically should never need to be lubed, but that just ain't so. They dry out rather quickly and do require attention at least once every two or three years...."

 

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Paul Scaglione on ACL sintered bushes/lubrication....1

I wrote to Paul Scaglione at Visual Products. He was very helpful and 
is fine if I share his insights here. Thanks Paul..!

From my email to Paul 25/May/2022....1
...confusion in the Eclair community about the lubrication of the ACL sintered bronze bushes. Popular knowledge, in line with the owners manual, is that these bushes are never lubricated. Ideas on this may vary, and different techs may have different protocols.

(then pointed him to this thread)

Can you share any insights into this?
- When you do a full overhaul of a movement, is it completely disassembled?
- Do you have a way of re-impregnating the bushes?
- If so, is the method and the lubricant used a secret?

 

Paul's email to me 25/May/2022...1
I've made some paragraph breaks and added a pause with ... a couple of times.

Hi Gregg,
I read your thread and all inclusive is correct...however, rarely if at all any more is any Eclair movement completely (or even partially for that matter) disassembled due to the time required/cost involved.

More often each reachable bushing is spot-lubricated with a light mineral oil such as Arcopac Oil 90 which is a very light mineral oil (actual sewing machine oil) that can wick in to the shafts/bushings and further wick in to the sintered bronze bearings to then release over time. ArcoPac is hard to find these days however any light mineral oil can work. I would avoid parafin-based oils as they may not play nice over time therefore here is an easily obtainable fine mineral oil with applicator:

https://www.amazon.com/Zoom-SPOUT-Sewing-Machine-Oiler-118ml/dp/B00BYCKTW2/ref=asc_df_B00BYCKTW2/?tag=hyprod-20&linkCode=df0&hvadid=194007750414&hvpos=&hvnetw=g&hvrand=15756312311447143080&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9015294&hvtargid=pla-311553017405&psc=1

Back in the day, the movements would be partially or completely disassembled and placed in a vacuum chamber in a light mineral oil bath over-night to "charge" the bearings...however all bushings & shafts, no matter what machine create a wear pattern (wear in) just as the inside of any combustion engine crankshaft & associated bearings would and therefore are better off left where they lay and fresh lubricant introduced as if disturbed can bind and get noisier over time from new wear patterns being established. 

If one has access to a vacuum pump & chamber and can completely immerse the movement and associated shafts (still mounted to the aperture plate and any lubricating point access screws removed) in a good light mineral oil and pull down to say 25" mercury for 2-3hrs, the oxygen will be drawn out of the microscopic cavities in the sintered bronze bushings as well as the open cavities in between and replaced by any oil introduced however most don't have access to that and the few technicians in the world still doing work on analogue cameras that may have a chamber more than likely don't have the time available to do the work for what most are willing to pay for it on an ACL... 

All that being said, if the inside of any Eclair can be spot-lubricated say once a year with any visible debris being surgically removed, it should last as long as it did prior to now.

Note: Pull-down claw guides and pinions as well as reflex mirror links (ball & sockets) can benefit from some fresh light grease such as Jet Lube Arctic which I have come to love over the last 20 years using in place of many specialized greases of different consistencies that seem to feel great at first then fade quickly into chalk, paste or goo... It can also be found on Amazon (pretty much like everything these days...): https://www.amazon.com/Jet-Lube-35050-Extreme-Temperature-Cartridge/dp/B000LG8DLG

Many points inside the ACL are very precisely adjusted for gear lash or pressure, clearance, claw stroke & penetration, shutter timing, reflex mirror swing & timing, etc. and should not be disturbed by anyone other than an understanding and experienced technician... therefore spot-lubricating with good greases/oils can go a long way to maintain these cameras for a very long time.

Having been a camera tech for 38 years has taught me a lot including cautious enthusiasm and wise restraint...

Good luck!
Paul Scaglione
Sr. Technician/Designer
Visual Products Inc.

Edited by Gregg MacPherson
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Paul Scaglione on ACL sintered bushes/lubrication..2

Gregg's email to Paul 25/May/2022....2

Hi Paul,
Many thanks for that reply. Excellent! I posted it on the forum. I might have a couple of short follow up questions. Using vacuum to replenish the bushes after removing some parts that won't like the oil sounds do-able, but I don't know enough to re-fit some things, the ground glass for example. So I might restrict myself to cautiously spot lubricating what's accessible, as you describe.

- I'm guessing that when applying oil at the juncture between shaft and bush it is just one tiny drop?
- Do the bushes absorb freely through their flange surfaces if more is applied? Or is that avoided?

Regards,
Gregg.

 

Paul's email to Gregg 25/May/2022....2

Again Gregg added some paragraph breaks. Some [edits] also, just so.

HI Gregg,
 Yeah... If using the vacuum chamber approach, the viewing optics could take a bath in the process as well unless A) Removed and once removed are a bitch to get back in alignment so B) The best way to avoid disaster would be to set assembly into a cup upright with just the moving parts in the oil bath and the optics above. 

After drawing it down [applying vacuum], you should invert the assembly over a pan to drain the excess oil out of the voids either side of the cross shaft next to the mirror drive and gently flush the viewing screen & prism (if needed) with a paint-safe solvent such as 91% isopropyl alcohol to get all the oil off the ground glass & prism as well as the reflex mirror letting it drain off in to the pan. 

You would just have to be careful not to accidentally get any [alcohol] in the cross shaft or any moving parts in the process. You could probably mask off a couple places with painter's tape just to be sure. Do not use electronic or any spray cleaner as it most times comes out of the can very cold and can separate or destroy optics!!!

 If spot-lubricating, the bushings will soak light oil in and oil should be added fairly generously; a couple drops/ea. That will help for sure and last for a year or more but would not "load" them the same as if vacuumed down in an oil bath. Ideally some disassembly would allow more access to those bushings however the pins that hold everything in place are tiny/tapered and nearly impossible to know the proper orientation of shaft -to- pinned part unless you very carefully scratch mating marks into both before disassembly which is where the wise restraint kicks in; 

Back to spot-lubing... When spot-lubricating, the hardest place to feel like you are getting oil where it need to be is the cross shaft end bushings (especially at the motor end) as the bushings are fairly buried within. If you can pretty generously shoot some oil into the areas either side of the beveled gear for the reflex mirror drive it should puddle along the casting inside void and get to those bearings with a bit of tipping the assembly side to side.

Any way you approach it, observance, planning and careful execution can work well to get oil where it can help and avoid getting it where is doesn't.

Hope all this helps!
Best,

Paul Scaglione
Sr. Technician/Designer
Visual Products Inc.

Edited by Gregg MacPherson
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