Repair filter threads on lens?

Called "thread reformer" Hint: look for page 330.

Regards,

Marv

Marv Soloff wrote:
You may want to try MSC

http://www.mscdirect.com/

They have an online catalog and (if you ask them) catalog on CD. Prices
are high but not unreasonable, shipping is excellent. They have a low
price sister company called ENCO -sometimes the same items are featured
in both places. You'll have to look.

Regards,

Marv

Winfried Buechsenschuetz wrote:

SNIP


Mechanists have a special tool for manually re-shaping threads, it is
called 'thread chaser'. I have access to such a tool but could not
find any source to buy it yet. Filter threads are metric and have
0.75mm pitch in most cases (0.5mm below roughly 40mm diameter),


Winfried

"David Littlewood" wrote in message
...

I believe camera lens filter threads are all 0.75mm pitch; certainly the
27mm filter thread on my Coolpix is - I cut a thread on a microscope
eyepiece last year to fit on it.

Don't I wish that were true. It just puzzles the heck out of my why B&W has
only the _wrong_ thread pitch for _one_ particular filter I need for the
Blad.

Industry in the UK is almost entirely metric.

Really? They finally got it right? In 72 or 73 when the world was metric,
and a lot of British iron was Witless (Wentworth, whatever), Triumph
Motorcycle went to _American_ thread sizes. What was that all about? OT?
You betcha!

I agree the USA is still mostly in the dark ages. The chemical engineers
there still use the Fahrenheit/Rankine temperature scale, for goodness
sake!

And a different operating definition of mass! Well, for many purposes. And
we wonder why they missed Mars.

In article ,
David Littlewood wrote:

I agree the USA is still mostly in the dark ages. The chemical engineers
there still use the Fahrenheit/Rankine temperature scale, for goodness
sake!

I was a lab technician in the USA from 1962 to 2000 and no technician,
engineer or chemist used Fahrenheit. As a matter of fact Fahrenheit
thermometers were not even stocked in our storeroom.

Our machinists were, however still using inches and their fractions and
decimals when I retired.
--
Charlie Dilks
Newark, DE USA

"Charlie Dilks" wrote in message
...
In article ,
David Littlewood wrote:

I agree the USA is still mostly in the dark ages. The chemical engineers
there still use the Fahrenheit/Rankine temperature scale, for goodness
sake!

I was a lab technician in the USA from 1962 to 2000 and no technician,
engineer or chemist used Fahrenheit. As a matter of fact Fahrenheit
thermometers were not even stocked in our storeroom.

Our machinists were, however still using inches and their fractions and
decimals when I retired.
--
The reason for this is that large metal working machines like lathes and
milling machines are very expensive, and they last virtually forever....So
if they are calibrated in inches, the operators just have to live with that.
At the lab where I worked, the machine shop took pride in their ability to
turn out items regardless of the dimension system used in the
specifications.
Another way to "fix" the bent filter ring is to buy a step-up ring that
goes from a millimeter or two smaller than your bent ring back to the bent
ring's original size, and then cement it in place permanently to the end of
your lens. I don't think this is the best solution....Only a different
solution.....

In article , Charlie Dilks
writes
In article ,
David Littlewood wrote:

I agree the USA is still mostly in the dark ages. The chemical engineers
there still use the Fahrenheit/Rankine temperature scale, for goodness
sake!

I was a lab technician in the USA from 1962 to 2000 and no technician,
engineer or chemist used Fahrenheit. As a matter of fact Fahrenheit
thermometers were not even stocked in our storeroom.

Well, true, but this is different. When I was a chemist (back in the
early 70s) all chemistry, even in the USA, was done using
Celsius/Kelvins. I was referring to chemical *engineering", which is a
completely different discipline (whose practitioners do almost no
chemistry at all). Of numerous chemical engineering books I bought
and/or looked at last year, *all* the US-sourced ones still used
Fahrenheit/Rankine temperatures.

Our machinists were, however still using inches and their fractions and
decimals when I retired.

--
David Littlewood

In article ,
David Littlewood wrote:

I believe camera lens filter threads are all 0.75mm pitch;

No. Depending on the size filters lenses have 0.5, 0.75, 1.0 and 1.5
pitch threads.

Heliopan has brass mounts on their filters up to 135mm diameter and many
sizes may have more then one pitch size. That is where the E and ES
designation on German filters comes from. One is for fine and the other
stands for coarse pitch threads.

--
To reply no_ HPMarketing Corp.

lib wrote:

I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the
front edge and has left the lens housing at that point slightly " out of
round " and unable to accept the filter. What is the process to repair
this problem? Thanx

Obtain a piece of hardwood, harder than oak but workable. It should be at
least a half inch thick and at least six inches across. Stand the lens on
the surface of the wood such that you can reach close to 180 degrees of
undamaged edge. Turn the lens so that the undamaged arc is square with an
edge of the wood, and carefully trace the perimeter of the lens with a
sharp pencil.

Now trim the wood so that the arc is bisected leaving the minor arc (less
than 180 degrees) on the work piece. With a jig-saw, cut the arc line.
You should now have the work piece with a semicircle removed, into which
the edge of the lens will fit somewhat snugly, not tightly. The removed
piece is retained as the 'hammer' to be used with this wooden 'anvil'.

Mount this work piece on a board, such that the lens can be fitted squarely
into the anvil and the entire thread surface is supported by the wooden
'anvil'. You'll have to cobble some dependable support for the lens body,
of course, and it's good to do this so when the lens is positioned, you'll
not have to worry about the lens moving in the jig.

Next, try the fit of the 'hammer' piece inside the filter thread.
Obviously, cover the front element of the lens, or you can wrap the
'hammer' with velvet or other protective cloth. Fiddle with this until you
are satisfied that it'll do the job without your having to tend to it. If
the 'hammer' doesn't fit inside the filter thread, sand it down until it
does, paying attention that the center of the arc isn't malformed. The
setup will require that the 'hammer' piece will be affixed (taped?) in
place.

Obtain a dowel, preferably hardwood, that is somewhat less in thickness than
the 'hammer' and 'anvil'. It should be probably six inches in length.

The setup will be with the lens placed in the jig so that the damaged part
of the thread is at the bottom. Secure the lens. Place the inner 'hammer'
wooden half-round such that it rests on the damaged part. Place the dowel
on the 'hammer', so that it is vertical, that the end that rests on the
'hammer' is as close as possible to a vertical alignment as possible. Now
you are ready to work.

With a small hammer or mallet, tap on the upper end of the dowel. You'll be
holding the dowel in place with your free hand, so that it doesn't move or
slip. DO NOT USE FORCE!!! Many light taps will do the job and it'll take
a little while. If you set this up so that you can see the damaged edge
between the 'hammer' and 'anvil', you'll be able to assess your progress.
Don't get impatient and hit it harder if you see little result, just stay
with the task.

When you are done, the damage should be remedied, such that a filter will
mount easily.

The jig and the 'hammer', with the dowel, is now ready to fix any dent in a
62 mm filter thread, and will serve as many of these as you're likely to
see, I think.

Re filters: There is a product used by tire sellers to lubricate the lug
threads of automobile wheels so that lug nuts will be easily removeable
without the tendency to loosen. It's an aluminum colored paste. It works
great on filters. But here's the caveat. It's rather difficult not to get
too much on the threads.

What you do is to touch the paste with the end of your finger. Wipe off the
paste until there is only a dull film on your finger-tip. Apply this to
the outer threads of the filter. If you do this right, it will be
difficult to discern the color of the film on the threads, but there will
be enough to keep them lubricated, such that they'll not be likely to jam.

HTH

Bill Tallman

In article 0teXb.174834$U%5.821111@attbi_s03,
"William Graham" wrote:

The reason for this is that large metal working machines like lathes and
milling machines are very expensive, and they last virtually forever....So
if they are calibrated in inches, the operators just have to live with that.
At the lab where I worked, the machine shop took pride in their ability to
turn out items regardless of the dimension system used in the
specifications.

I know their problem. I was just mentioning it since when we in the US
had our "official metric mandate" in the '70s or whenever I bought a
metric micrometer and dial caliper to use in the lab. I never did get to
use them.

I know you didn't infer it, but I was in =no= way demeaning machinists.
The ones I dealt with performed magic.
As an example, I once needed a stainless steel bar made to fit into a
slot in a piece of stainless steel that had already been cut. It was
around an inch wide, 3/4 inch thick and 20 inches long. Instead of me
tearing the apparatus apart and bringing the piece with the slot up to
the shop the guy I was working with he thought he would be able to make
the piece from his meticulous measurements.

After the temperature of the piece equilibrated it slowly slipped into
the slot as the air was displaced. It fit almost as well as the plunger
in a glass syringe. Just as it was supposed to.
--
Charlie Dilks
Newark, DE USA

"jjs" wrote in message ...
"David Littlewood" wrote in message
...

I believe camera lens filter threads are all 0.75mm pitch; certainly the
27mm filter thread on my Coolpix is - I cut a thread on a microscope
eyepiece last year to fit on it.

Don't I wish that were true. It just puzzles the heck out of my why B&W has
only the _wrong_ thread pitch for _one_ particular filter I need for the
Blad.

Maybe it's a Series xx filter thread. I am not sure about the pitch
but the diameter of the Series xx filter thread is not metric.

And a different operating definition of mass! Well, for many purposes. And
we wonder why they missed Mars.

Well, recently they hit it quite exactly... better than the Europeans.
That failed mission was due to some confusion about distances which
were partly defined in km and partly in ft by the NASA.

Winfried

"William Graham" wrote in message news:0teXb.174834$U%5.821111@attbi_s03...
--
The reason for this is that large metal working machines like lathes and
milling machines are very expensive, and they last virtually forever....So
if they are calibrated in inches, the operators just have to live with that.
At the lab where I worked, the machine shop took pride in their ability to
turn out items regardless of the dimension system used in the
specifications.

I am not sure about that. Most, if not all, machines can be equipped
with electronic measuring systems, we have some 20+ years old milling
machines with such equipment, and you just press a button to switch
from inches to mm. There are some companies specialised in equipping
old machines with modern measuring systems and sometimes they can even
convert them to automatic operation by adding motor drives where you
once had to turn manually.

It may be different for cutting threads. In these cases, the pitch of
the spindle and/or the number of teeth on some gears are important,
and they can't be changed easily. However, with most lathes
manufactured in Germany it is no big problem to convert them to
cutting inch-dimension threads.

Threads for tubing (water, gas and air tubes and their fittings) are
still in inch dimensions even in Germany, and I have severe doubts
whether this will ever change.

Winfried