Lens front element retaining ring stuck...help!

rrocco · Jan 14, 2012

Hi,
I'm trying to remove the front element of a lense with some haze below that element.
I'm using a spanner wrench, turning counterclockwise and its not budging.
It's a pretty nice lense without rust, corrosion or anything like that.
Took the front cell out of the lens barrel and heated the outer rim on top of a hot toaster, but did not help.
I'd greatly appreciate any suggestions to get this sucker loose.
Thanks.

Rob

Jon Shiu · Jan 14, 2012

Not knowing what type of lens it is, here are some tips: clamp the part down so it doesn't rotate. Then use some sort of wrench to hold the spanner to apply more force.

Jon

rrocco · Jan 14, 2012

Tried clamping it down in a vise and am using quite a bit of force on the spanner wrench. The notches for the spanner wrench on the retaining ring are a couple millimeters away from the front element, so I'm afraid if I slip I'll destroy the front element.

brucemuir · Jan 14, 2012

Are u sure there isn't a set screw (maybe under the focussing rubber)?

Can you identify the exact lens so someone can better help?

E. von Hoegh · Jan 14, 2012

rrocco said:
Tried clamping it down in a vise and am using quite a bit of force on the spanner wrench. The notches for the spanner wrench on the retaining ring are a couple millimeters away from the front element, so I'm afraid if I slip I'll destroy the front element.

You are squeezing the lens oval and jamming the retaining ring. Never put anything like this anywhwere near a vise, much less in it.

Try a tiny bit of penetrant on the ring.

rrocco · Jan 14, 2012

brucemuir said:
Are u sure there isn't a set screw (maybe under the focussing rubber)?

Can you identify the exact lens so someone can better help?

The lense is a Schneider componon s 80mm f4 enlarging lens.
I have the front cell removed from the lense assembly, so it appears to just be the retaining ring.
Thanks.

ic-racer · Jan 14, 2012

My recipe for stuck element retaining rings.

1) look for or suspect it was 'locked' with a drop of lacquer or some other substance. All the Fujinon LF lenses I have cleaned are locked with a drop of something dissolvable in acetone.

2) Heat is your friend. It expands both the barrel and the ring and loosens it up.

3) Use a "Jar opener" or rubber gloves for traction on the barrel.

rrocco · Jan 14, 2012

E. von Hoegh said:
You are squeezing the lens oval and jamming the retaining ring. Never put anything like this anywhwere near a vise, much less in it.

Try a tiny bit of penetrant on the ring.

I had the cell wrapped in a thick layer of gaffer tape and had it in the vise just tight enogh so it wouldn't rotate and I could use both of my hands.
The penetrant sounds like a good idea. Thanks.

E. von Hoegh · Jan 14, 2012

rrocco said:
I had the cell wrapped in a thick layer of gaffer tape and had it in the vise just tight enogh so it wouldn't rotate and I could use both of my hands.
The penetrant sounds like a good idea. Thanks.

If you are clamping it hard enough to prevent it rotating, you are squeezing it out of round. Tape makes no difference. You need to clamp it so it is held evenly around the cell, say in a collet on a lathe.

rrocco · Jan 14, 2012

A little bit of penetrant and extra heat got the job done!
Thank you all for your help.

Rob

Lens front element retaining ring stuck...help!

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