Lubricating Mini35 at DVinfo.net

Oleg Kalyan · March 16th, 2008, 02:10 AM

It's a general question, any lubrication ought to be done on moving parts particularly the bearing of the GG ?

Mine makes some little noise from time to time like it needs some lubrication work.

Appreciate any thoughts, info!

Bob Hart · March 16th, 2008, 09:29 AM

As I understand things and I may well be wrong, the Mini35 uses "sealed-for-life" bearings.

If there is no ring of oil creeping in around the edge of your groundglass, the lubricant should be still in the bearings. Oil creep apparently only occurred in earlier Series 400 production before the lubricant was changed.

Noise may be a hint of a bearing becoming worn, maybe a fastener becoming loose allowing some end-float, or the ring retainer holding the groundglass in its rim working loose slightly.

This is all highly uninformed speculation on my part and not to be taken too seriously. However, the mechanics of the Mini35 are too finely engineered for unusual noises to be ignored.

The deep mechanical internals of the Mini35 are not conveniently user serviceable and some special tooling is required to get at the groundglass carrier or "swing module" as they call it. Beyond checking the four screws around the rear cover to see if they are loose and allowing the cover to vibrate, I would not mess with it.

It may be prudent to send P+S an email or have them service it rather than attempt to do anything yourself.

Oleg Kalyan · March 16th, 2008, 10:41 AM

Bob! Thank you very much for your prompt response.

Oleg.

Steve Cahill · March 16th, 2008, 08:15 PM

The screws are locked down so much that you may strip the head trying to remove since they used flat heads instead of philip head, I think they may be held in place with locktite, I tried to undo one but it would not budge.
Best NOT to touch.

Bob Hart · March 17th, 2008, 03:34 AM

The reason I suggested loose screws because this is what I found. They may be well secured when the device leaves P+S but if an uncontrollable third agency, the human hand of another owner has intevened between the last touch of P+S Technik and your first, then the screws just might be loose.

Getting that rear plate off with the prisms and mirror attached to it is the easy part. Beyond that there are some special service tools needed so about all you are able to do is clean the flip path and likely allow some dust and specks in while you are exploring.

It is probably best not to go inside. The P+S is assembled by optical engineers and has some construction tricks unique to lens and camera building which you may not find used as extensively on the alternative adaptors.

If you do not want to ship the Mini35 to a workshop just yet, but want some reassurance it is not destroying itself, shine a strong torch in through the back while you look at the groundglass.

If the groundglass is not also slowly rotating anti-clockwise in its rim as it oscillates or there is no oil or dry powery looking deposit on the rim where the groundglass meets it, then there may be no problem that can't wait a while.

If a bearing has begun to fail it may damage the hole or the pillar it is mounted on if it is left too long and it locks up. Noise from a failing bearing will get progressively worse.

To see if a bearing has failed or the pillar and hole it fits to have not themselves worn to a loose clearance, look at the groundglass motion pattern while the motor is running. There are two handy ways to do this.

On-camera, set your 35mm still-camera lens to a tight aperture and the camera iris wide open like you do for setting correct focus of the camera on the groundglass.

Set the shutter speed to 1/500th sec or faster and add light to make the image bright enough. Turn the groundglass motor on.

With the shutter speed high, you should see a "swirling artifact" in the groundglass. If you can zoom back to study the motion of the rim, if visible it will have been be slowed down in a strobe effect.

If the mechanism is good, the pattern of movement should be circular.

If the pattern of movement has a shape like a rugby football (elliptoid shape), any sharp corners or a figure of eight look to it, then the mechanism probably needs to be checked.

Off-camera, while you look through the Mini35, hold it up in front of an operating CRT television set. The groundglass motion when it is operating may become more visible in a strobing effect and motion defects will become apparent.

On or off-camera, use the speed control of the Mini35 to get the strobe affect against the camera frame rate or the CRT screen to slow the apparent motion down.

Then you will be able to see if something has worked loose because the motion may no longer be a true circle or it may lurch every now and then if a bearing is worn and is running out.

Do not accept my suggestions as having any worth.

Oleg Kalyan · March 17th, 2008, 04:57 AM

Bob, great info!
You are fantastic, I can't express enough my gratitude for your prompt and complete analysis, and explanation!

I will take a video of the symptom and if you don't mind will post on my site, will appreciate if you take a look, you seem to be a specialist in that matter and are extremely kind person to take you time and help fellow filmmakers!

Bob Hart · March 17th, 2008, 08:41 AM

Oleg.

What might be better for you is record the image your camera sees, put a microphone close to pick up what you think is abnormal noise, make a copy on DVD-Video disk of this and send to P+S Technik or their nearby reseller to ask for their advice.

They know their own machine best. When they build them, they collimate the groundglass to the front flange with a special rig just like camera builders do.

It is very precise engineering with reverse projection and fine shims to get it backfocussed right so I would not try to dismantle and service the moving parts.

I am no expert. Myself and the owner pulled the back off one to do an urgent repair at a music video shoot. (Look up "Antistatic" "The Coping Mechanism" on YouTube and you will find the clip which was shot on it.

The owner just about had kittens from anxiety when the back came off. I was happy to get a good look inside. If it broke, it was not going to cost me. If it had not been urgent to get it fixed, I would not have done it.

There was a little chip of locktite had come off onto the field lens behind the groundglass and it was showing up on the image. We got lucky because no dust or hairs got in while we had the back off it on set.

That is about as close as I have been to mechanical workings of the Mini35. I will try to download your images but I may not have much luck as my download speed is slow.

Please do not let my comments encourage you to pull it apart yourself. P+S will have proper and better ways of looking for problems. If you ask the people there, they will probably be happy to help as you are an owner.

March 16th, 2008, 02:10 AM	#1
Oleg Kalyan Major Player Join Date: Apr 2006 Location: MOSCOW Posts: 860	Lubricating Mini35 It's a general question, any lubrication ought to be done on moving parts particularly the bearing of the GG ? Mine makes some little noise from time to time like it needs some lubrication work. Appreciate any thoughts, info!

March 16th, 2008, 08:15 PM	#4
Steve Cahill Major Player Join Date: Dec 2003 Location: Boston, MA Posts: 321	The screws are locked down so much that you may strip the head trying to remove since they used flat heads instead of philip head, I think they may be held in place with locktite, I tried to undo one but it would not budge. Best NOT to touch. __________________ Regards Steve

March 16th, 2008, 09:29 AM	#2
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	As I understand things and I may well be wrong, the Mini35 uses "sealed-for-life" bearings. If there is no ring of oil creeping in around the edge of your groundglass, the lubricant should be still in the bearings. Oil creep apparently only occurred in earlier Series 400 production before the lubricant was changed. Noise may be a hint of a bearing becoming worn, maybe a fastener becoming loose allowing some end-float, or the ring retainer holding the groundglass in its rim working loose slightly. This is all highly uninformed speculation on my part and not to be taken too seriously. However, the mechanics of the Mini35 are too finely engineered for unusual noises to be ignored. The deep mechanical internals of the Mini35 are not conveniently user serviceable and some special tooling is required to get at the groundglass carrier or "swing module" as they call it. Beyond checking the four screws around the rear cover to see if they are loose and allowing the cover to vibrate, I would not mess with it. It may be prudent to send P+S an email or have them service it rather than attempt to do anything yourself.

March 16th, 2008, 10:41 AM	#3
Oleg Kalyan Major Player Join Date: Apr 2006 Location: MOSCOW Posts: 860	Bob! Thank you very much for your prompt response. Oleg.

March 17th, 2008, 03:34 AM	#5
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	The reason I suggested loose screws because this is what I found. They may be well secured when the device leaves P+S but if an uncontrollable third agency, the human hand of another owner has intevened between the last touch of P+S Technik and your first, then the screws just might be loose. Getting that rear plate off with the prisms and mirror attached to it is the easy part. Beyond that there are some special service tools needed so about all you are able to do is clean the flip path and likely allow some dust and specks in while you are exploring. It is probably best not to go inside. The P+S is assembled by optical engineers and has some construction tricks unique to lens and camera building which you may not find used as extensively on the alternative adaptors. If you do not want to ship the Mini35 to a workshop just yet, but want some reassurance it is not destroying itself, shine a strong torch in through the back while you look at the groundglass. If the groundglass is not also slowly rotating anti-clockwise in its rim as it oscillates or there is no oil or dry powery looking deposit on the rim where the groundglass meets it, then there may be no problem that can't wait a while. If a bearing has begun to fail it may damage the hole or the pillar it is mounted on if it is left too long and it locks up. Noise from a failing bearing will get progressively worse. To see if a bearing has failed or the pillar and hole it fits to have not themselves worn to a loose clearance, look at the groundglass motion pattern while the motor is running. There are two handy ways to do this. On-camera, set your 35mm still-camera lens to a tight aperture and the camera iris wide open like you do for setting correct focus of the camera on the groundglass. Set the shutter speed to 1/500th sec or faster and add light to make the image bright enough. Turn the groundglass motor on. With the shutter speed high, you should see a "swirling artifact" in the groundglass. If you can zoom back to study the motion of the rim, if visible it will have been be slowed down in a strobe effect. If the mechanism is good, the pattern of movement should be circular. If the pattern of movement has a shape like a rugby football (elliptoid shape), any sharp corners or a figure of eight look to it, then the mechanism probably needs to be checked. Off-camera, while you look through the Mini35, hold it up in front of an operating CRT television set. The groundglass motion when it is operating may become more visible in a strobing effect and motion defects will become apparent. On or off-camera, use the speed control of the Mini35 to get the strobe affect against the camera frame rate or the CRT screen to slow the apparent motion down. Then you will be able to see if something has worked loose because the motion may no longer be a true circle or it may lurch every now and then if a bearing is worn and is running out. Do not accept my suggestions as having any worth.

March 17th, 2008, 04:57 AM	#6
Oleg Kalyan Major Player Join Date: Apr 2006 Location: MOSCOW Posts: 860	Bob, great info! You are fantastic, I can't express enough my gratitude for your prompt and complete analysis, and explanation! I will take a video of the symptom and if you don't mind will post on my site, will appreciate if you take a look, you seem to be a specialist in that matter and are extremely kind person to take you time and help fellow filmmakers!

March 17th, 2008, 08:41 AM	#7
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	Oleg. What might be better for you is record the image your camera sees, put a microphone close to pick up what you think is abnormal noise, make a copy on DVD-Video disk of this and send to P+S Technik or their nearby reseller to ask for their advice. They know their own machine best. When they build them, they collimate the groundglass to the front flange with a special rig just like camera builders do. It is very precise engineering with reverse projection and fine shims to get it backfocussed right so I would not try to dismantle and service the moving parts. I am no expert. Myself and the owner pulled the back off one to do an urgent repair at a music video shoot. (Look up "Antistatic" "The Coping Mechanism" on YouTube and you will find the clip which was shot on it. The owner just about had kittens from anxiety when the back came off. I was happy to get a good look inside. If it broke, it was not going to cost me. If it had not been urgent to get it fixed, I would not have done it. There was a little chip of locktite had come off onto the field lens behind the groundglass and it was showing up on the image. We got lucky because no dust or hairs got in while we had the back off it on set. That is about as close as I have been to mechanical workings of the Mini35. I will try to download your images but I may not have much luck as my download speed is slow. Please do not let my comments encourage you to pull it apart yourself. P+S will have proper and better ways of looking for problems. If you ask the people there, they will probably be happy to help as you are an owner.