[rollei_list] Re: New List Member & Focus "Glide Pieces"
- From: John Wild <JWild@xxxxxxxxxxxxxxxxxxxxxx>
- To: "rollei_list@xxxxxxxxxxxxx" <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 17 Oct 2013 17:08:12 +0100
Bret,
I did receive your original email a few weeks ago but because I am no
expert, I thought I would leave any suggestions to others better qualified.
It 'looks as if, for some reason, others did not receive it, so I will throw
in my two-penne'th.
I disassembled an Automat a couple of months ago, and I did notice on the
focus linkages that there was a cylindrical friction pad either side.
Because they were covered in grease, I did not look further intending to
clean them up on reassembly (not happened yet!); I seem to remember they
were kept under pressure against the cam by a spring...
My guess is that they are there to remove any slackness that will be present
when racking the focus knob backwards and forwards, so the response seems
instantaneous rather than there being a little backlash.
You say that they are fibre. My guess is that being fibre, they will hold a
lubricant - carbon dust or similar - and also will be a sacrificial material
so the brass does not wear. There would not have been the same variety of
engineering plastics available at the time so this probably would have been
the most suitable material. Mylar may have been used.
I guess that nylon would be a possible substitute material but I would
personally use "Delrin" (or acetyl) rod being easier to machine and not so
'abrasive' as nylon, because you can machine it to a very fine finish. I
find that Nylon is more pliable and tends to 'tear' rather than to cut
smoothly, leaving a rougher surface than with Delrin. Delrin may not have
the longevity of nylon though. PTFE would also be an excellent bearing
material...
I hope this may be of assistance. I would think that genuine replacement
pads would be hard to find now unless they are still used by DHW in current
TLR cameras - they may have a modern alternative; probably worth an email...
John
On 17/10/2013 09:12, "Brett Rogers" <rogersbretta@xxxxxxxxxxx> wrote:
> "Greetings List Members, I have recently worked out how to join and post to
> the
> list after perusing the archives over a couple of years in search of Rollei
> repair lore. I am the owner of several Rolleicords and Rolleiflexes based in
> Australia. I've mostly been using my 2.8C Xenotar lately but have loved using
> my Rolleicord V & Va models and have several projects awaiting my time,
> including a 2.8D Xenotar and Rolleicord Va and V.
>
> I'd appreciate some input please, on the topic of what the Rollei Repair
> Manual
> refers to as "glide pieces". AKA as the fibre cam followers that are located
> between the focus cams and the U bracket supporting the lens carrier. Ie.
> those
> pads at the front side of the focus cams.
>
> I should add, at this point, that I've been successful in persuading several
> Rolleicords back to life as regular users with great results on film over
> several years. The last one I tackled was a Rolleicord Vb with wear in the
> focus system, that required resetting of the parallelism between the film
> rails
> and the lens board. I found this to be a fiddly exercise, and had to fabricate
> a number of shims to achieve correct alignment, but got it right in the end (a
> measured 0.03mm across the corners, within the factory spec of 0.05mm). So I
> am
> not a total newbie when it comes to Rollei repairs, but like all of us, am
> always learning, or trying to.
>
> Back to those pesky glide pieces. Those who have performed their own repairs
> will be aware that these are
> often found in worn condition depending on how much use and care an
> example has had. It seems, from my observations of various Rolleis, that
> procuring good used pairs of these from a donor camera is problematic
> because they're often in less than ideal condition for re-use. Have
> members been able to procure new replacements of these crucial parts used in a
> number of the later Rolleicord and Rolleiflex models?
>
> I have enormous respect for the quality of Franke & Heideckes design and
> manufacturing skills, so I do not wish to second guess or to improve on their
> designs. However, in the absence of good used glide pieces to replace worn
> originals, I find myself wondering if other materials may be substituted
> successfully in place of the original parts, in order to keep these cameras
> working well into the future. I've been considering fabricating replacement
> glide pieces from, for instance, nylon, as a substitute for fibre. Do any of
> you have any experience trying this?
>
> Secondly, I've found the differences and similarities between the Rolleicord
> and Rolleiflex focus mechanisms interesting and have a question about this.
> When I corrected the focus alignment of the Rolleicord Vb, one of the issues
> was some wear in the focus rails. The consequence of this was that the first
> initial movement of the focus knob would not to translate to immediate
> extension of the lens board. A small amount of side thrust (Ie. up and down
> motion as viewed from the side of the camera body) would be induced by the
> sliding motion of the cams across the "glide pieces"), which had to be
> absorbed
> before the lenses would extend to sub-infinity focus settings. I'm sure many
> of
> us are familiar with the "rocking" action from the top and bottom of the lens
> carrier, that this wear will encourage.
>
> I found correcting the side play between the lens carrier and the rails of the
> Vb quite straightforward. The Rolleicords (at least the later ones) feature a
> simple wedge adjuster on either side, below the rail. I was able to quite
> satisfactorily correct the clearance to the necessary minimum by using the
> position of the wedges to eliminate excess play. However the Rolleiflex does
> not, as far as I can see, have a similar adjuster. Whilst the two guide posts
> fitted to the Rolleiflex would appear to offer superior axial alignment across
> the full focus range of the lenses compared to the Rolleicord mechanism,
> excessive clearance between the focus rails, the lens carriage and the camera
> body still work against immediate, simultaneous travel of each side of the
> carriage, when the focus knob is actuated. So adjustment is still necessary.
> Presumably replacement of worn focus rails would be one solution; once again,
> the issue of procuring usable replacement parts arises. The play is, as seems
> often to be the case, most evident at and just off the infinity position, and
> is less apparent at closer focus distances. It's likely that the deft use of a
> small hammer and punch to the rearward part of the rails would have the
> desired
> result of eliminating said excess clearance. However if there is a better,
> factory sanctioned method of adjusting this wear, I would be pleased to know
> what that is.
>
> I should add the current repair patient is a Type one Tele Rolleiflex, and
> that, doubtless, the strain of transporting those two 135mm lenses has
> aggravated the wear typically suffered by 80mm or 75mm Rolleiflex models.
> Replacement of the glide pieces is not optional as the wind side (why is it
> *always* the wind side?) one has collapsed. The focus side of the lens carrier
> would therefore"lead" the wind side by at least a millimetre off of infinity,
> so it simply has to be dealt with.
>
> If no sensible alternative solutions are suggested, I'll likely fabricate some
> new glide pieces out of a substitute material and see how that goes, but all
> input gratefully received. My apologies for such a lengthy first post.
> Best,
> Brett Rogers"
> -----------------------------------------
>
>
> The silence has been deafening. Was it something I said? Or some other faux
> pa?
>
> I had thought the members of this list included members willing and able to
> conduct some repairs themeselves. Richard Knoppow and Todd Belcher are a
> couple who come to mind. I would have regarded my original post as "on topic"
> so the absence of replies puzzles me. Or does nobody have any words of wisdom
> to proffer? ---
> Rollei List
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