Nikon F3: Disassembly of the mechanical release/exposure lock switch (plastic version)

Andreas Thaler · Dec 15, 2024

Since I'm removing this switch as a spare part for a colleague, here's the process.

Interestingly, I couldn't find any information about this in the Nikon F3 service manual.

This is the first version of the button made of plastic, see below in the thread the note from @Mamiya_Repair:

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All information provided without guarantee and use at your own risk.

forest bagger · Dec 15, 2024

The knob for exposure lock is known for getting lost due to wearing of the plastic shaft.

John Salim · Dec 15, 2024

My exposure lock knob fell out last year and would like to replace it.
If I can find one, does it literally just push back in ?

John S

Andreas Thaler · Dec 15, 2024

forest bagger said:
The knob for exposure lock is known for getting lost due to wearing of the plastic shaft.

On my F3 the shaft is made of metal, only the button is made of plastic.

Andreas Thaler · Dec 15, 2024

John Salim said:
My exposure lock knob fell out last year and would like to replace it.
If I can find one, does it literally just push back in ?

John S

Yes, the button should just be plugged in. At the bottom it activates a switch for storing the measured values.

If you are interested, I can show you the structure on the back of the front panel.

forest bagger · Dec 15, 2024

Andreas Thaler said:
On my F3 the shaft is made of metal, only the button is made of plastic.

I don't belive that, Andreas - or is your F3 a Press model?
The problem with the shaft of the knob is, that it has a bulge near the inner end which rubs off after decades of use.
As the bulge shall prevent the knob from falling out these knobs get lost some times...

Andreas Thaler · Dec 15, 2024

forest bagger said:
I don't belive that, Andreas - or is your F3 a Press model?
The problem with the shaft of the knob is, that it has a bulge near the inner end which rubs off after decades of use.
As the bulge shall prevent the knob from falling out these knobs get lost some times...

I'm not sure what material it is, I'd have to scratch it with a scalpel, but I don't want to do that.

MattKing · Dec 15, 2024

Andreas Thaler said:
I'm not sure what material it is, I'd have to scratch it with a scalpel, but I don't want to do that.

How does the shaft respond to a magnet?

Andreas Thaler · Dec 15, 2024

MattKing said:
How does the shaft respond to a magnet?

Negative, but it could also be a non-magnetic metal.

I think it doesn't matter, anyway it seems to be rare as a spare part, as the parts supply for the F3 is generally poor.

Andreas Thaler · Dec 15, 2024

forest bagger said:
The problem with the shaft of the knob is, that it has a bulge near the inner end which rubs off after decades of use.
As the bulge shall prevent the knob from falling out these knobs get lost some times...

Then it will actually be plastic that wears down through use.

Mamiya_Repair · Dec 15, 2024

First production Nikon F3 models used a plastic knob and shaft. As mentioned, the plastic wears away and the button no longer is held in place so it falls out and often gets lost. Nikon changed the exposure lock button to all metal at some point and it is held in with a clip from the back so it does not fall out. To remove the later model metal exposure lock buttons, the front plate of the camera needs to be removed.

forest bagger · Dec 15, 2024

Andreas Thaler said:
Then it will actually be plastic that wears down through use.

Exactly, Andreas.
I fixed this problem by adding a very tiny drop of one-second-glue on the bulge and grind down the newly build bulge a bit.

Andreas Thaler · Dec 16, 2024

Thanks everyone for the information!

Andreas Thaler · Dec 16, 2024

Mamiya_Repair said:
First production Nikon F3 models used a plastic knob and shaft. As mentioned, the plastic wears away and the button no longer is held in place so it falls out and often gets lost. Nikon changed the exposure lock button to all metal at some point and it is held in with a clip from the back so it does not fall out. To remove the later model metal exposure lock buttons, the front plate of the camera needs to be removed.

I have added a reference to the plastic version of the button to the thread title and my first posting.

MFstooges · Dec 16, 2024

I'm curious to know how much will it cost to turn this small part on a lathe by a machinist

John Salim · Dec 16, 2024

Andreas Thaler said:
Yes, the button should just be plugged in. At the bottom it activates a switch for storing the measured values.

If you are interested, I can show you the structure on the back of the front panel.

Yes please Andreas, I'd like to see that if it's not too much trouble - thank you.

John S

Andreas Thaler · Dec 16, 2024

John Salim said:
Yes please Andreas, I'd like to see that if it's not too much trouble - thank you.

John S

Front panel, front view, mechanical release/exposure lock switch removed.

Front panel, rear view, in the middle - under the transparent plastic cover - the release magnet.

This plate (red arrow) moves backwards when the button for storing the measured values is pressed. It rotates to the right when the mechanical shutter release is turned. In doing so, the plate contacts the shutter switch (green arrow) above.

The complex shutter switch from below.

Information about the shutter switch in the service manual for the F3.

delahp · Tuesday at 11:32 AM

Hi Andreas,

thank you for sharing, would you have more pictures of the button (top, bottom and front view) of the button please? I am trying to 3d print a new button but I need the dimensions. could you also describe the shape and position of the bulge? is it a bulge on the shaft that holds the button or is there a bulb at the end of the shaft.

thanks,
Pierre

John Salim · Tuesday at 3:33 PM

Thanks very much for sharing those pictures Andreas. I find the whole F3 mechanism so fascinating !

John S

Andreas Thaler · Wednesday at 12:34 AM

delahp said:
Hi Andreas,

thank you for sharing, would you have more pictures of the button (top, bottom and front view) of the button please? I am trying to 3d print a new button but I need the dimensions. could you also describe the shape and position of the bulge? is it a bulge on the shaft that holds the button or is there a bulb at the end of the shaft.

thanks,
Pierre

I'll take a few more photos and get back to you soon.

Andreas Thaler · Wednesday at 12:35 AM

John Salim said:
Thanks very much for sharing those pictures Andreas. I find the whole F3 mechanism so fascinating !

John S

You are welcome!

Yes, everything is still solidly designed and resilient.

Nikon F3: Disassembly of the mechanical release/exposure lock switch (plastic version)

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