Copal #3 Disassembly and Cleaning

ic-racer

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I don't see any good resources for opening and cleaning a Copal #3 shutter so I thought I'd share some pictures.

My Fujinon 300mm/5.6 is in a Copal 3, and when I went to use it I noticed the slow speeds were off. So I took it to my shutter tester and found 1 second = almost 2 seconds.

All the speeds were slow up to the top speed which should be 1/125 but measured 1/40th.

 
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ic-racer

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Three screws to remove the escapement:

 
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The mechanism was cleaned with a suitable solvent and then the bearing surfaces lubricated with thin oil.
 
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ic-racer

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On the Copal #3, the screws to separate the halves are in the front, not on the back. So no need to remove the aperture lever assembly on the back.
To separate the halves, the knob on the shutter preview lever needs to be removed. Once the screws are loose , the blades are no longer held in place and they will fall out (yellow arrow).

 
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ic-racer

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Afrer separating the halves, the shutter blades are free. For re-assembly, the blades need to be transferred over to the other side.

If you need to service the aperture blades, now they can be reached. However, re-assembly of the aperture is very tedious, so don't remove anything on the back plate unless you are committed to totally re-assembling the aperture mechanism.
 
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ic-racer

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To make sure the blades move freely, the sector ring and retainer should be removed and cleaned. To do that remove the five screws shown:

 
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ic-racer

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After cleaning, and when replacing the sector ring, the two springs need to straddle the tab as shown:

 
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ic-racer

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Also, clean the channel in which the sector wheel spins:

 
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ic-racer

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Reassembly can be made easier by removing the three assemblies shown. Because the manual shutter lever (preview lever) and the red indicator flag both need to fit through slots in the body while it is upside down as the two halves are being re-assembled:

 
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ic-racer

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Remove these levers, keeping in mind the re-assembly order as follows:

 
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ic-racer

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We needed to get the springs on these shafts out of the way, otherwise it is very difficult to get it back together:

 
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ic-racer

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I held the shutter-cocked flag in place with some tape:

 
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The whole assembly is turned up side down and the blades (which have been cleaned and dried) re-assembled on their pins:

 
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ic-racer

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When putting the halves together, don't tip it because the shutter blades will fall out of position. The picture is upside down to show how it will look. During assembly, the red flag needs to peek through the slot (red arrow) and the un attached preview lever (not shown) needs to pass through its slot (blue arrow).

When the two halves are solidly together, the whole assembly can then be turned over.
 
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ic-racer

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Reassemble the levers and springs in reverse order. Make sure the springs are back in place (green arrows).
Also note the relationship between the internal and external release levers (orange arrow).

Bottom picture shows grease (green) and oil (orange) points. Basically, grease on metal to metal contact and oil on rotating parts and shafts.
Of course no lubrication on the shutter blades or the sector wheel.
 
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ic-racer

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All back together:
 
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Initial speeds:

1 sec = 1.65
1/2 = 1.0
1/4 = 1/2
1/8 = 1/4.1
1/15 = 1/7.6
1/30 = 1/12
1/60 = 1/28
1/125 = 1/40

Final speeds. Still a little slow at the top end, but much better than before.

1 sec = 1.23 +0.3
1/2 = 1/1.7 +0.3
1/4 = 1/3.2 +0.3
1/8 = 1/7.4 +0.3
1/15 = 1/13 +0.2
1/30 = 1/28 +0.1
1/60 = 1/45 +0.4
1/125= 1/90 +0.5
 
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koraks said:
Excellent, thanks for posting this! Might come in handy one day, although I hope it's a long time off, yet...
Click to expand...

I got this shutter in 2008, so I got many years from it and hope for many more.
 

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Great presentation. I have several lenses in Compur Electronic 3 shutters, they are relatively simple in that they have 1 mechanical speed, the fastest, that is controlled by resistors/capacitors for slower speeds. Looks like the service required is similar to the Copal 3 but without the mechanical control of speeds. Have you "serviced" a Compur Electronic shutter in sizes 1 or 3?
 
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