Tair 3 (Grand Prix Brussels 1958) dismantling guides ?

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

Hello.

I've got this lens. The general cleaning/dismantling guides are available for later and photosniper models, which look like to have different construction. Anyone have experience with disassembly of this particular type? I want to get acces to helicoid, to clean and re-lube. It is very stiff currently.

BurstMox · Expire: 2016-08-02

I think Tair-3A is a bit more close to yours than photosniper, at least, focus and diaph rings are positionned quite the same. So it may help you : http://fotki.yandex.ru/users/foto-tair-3a/album/89802/

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

Checked the origin to that photos. It says that disassembly is not possible unless the special wrench is manufactured (shown on photo).

marcusBMG · Joined: 07 Dec 2012 Posts: 1298 Location: Conwy N Wales

Did you get any further with your Tair, CuriousOne?

I also have a tair 3A, I posted a thread on pentax forums detailing how far I got

http://www.pentaxforums.com/forums/120-general-technical-troubleshooting/247215-tair-300a-refurb-got-far-pics-help.html

I did establish that the sticky focus on mine is not a gooey helicoid but the felt that seals the space between the barrels.

I would like to know what needs to be unscrewed with the custom wrench - it looks like a tool that can be improvised.

Gamera · Joined: 16 Feb 2014 Posts: 86 Location: Scandinavia

I've done it partially with an early Grand Prix... lens, 002XXX.

Here's a short description of the process.

You need a screwdriver which is an exact match to those extremely tiny screws locking the parts together. If the profile of the screwdriver's tip is wedge shaped, forget it. You need one which reaches the bottom of the slot on the screw.
Also, a lupe or a binocular scope with sufficient working distance is strongly recommended.

You can do without step 1, but removing the glass elements makes later working with the helicoid much easier and lighter.

Step 1.

Clean the slots of the three screws holding the glass assembly. One is located between infinity and M, one closer to four and the last one between seven and eight. Under the scope, try to release the screws. Screwdriver should be strictly vertical according to the screw. Be gentle and take care not to bend the soft metal flanges, or break them. If You are handy and lucky the screws start to move. Loosen them just about two turns (or take them off now if that's Your style). You can now unscrew the glass assembly. It has normal threading. It may be a bit tight to start. The thread is long, once You have the glass assembly off, put it in some safe place and screw back in the three locking screws for a while.

Step 2.

Between the tripod mount and the remaining knurled ring is another set of three tiny screws. These should be also cleaned and gently opened about two turns, preferably under scope. The sleeve with the knurled ring has also a normal threading and You can now turn it loose, it won't come off completely. At this point You can tighten the locking screws a bit if You haven't taken them off. Setting the helicoid to close focus and moving the loose sleeve around gives partial access to the helicoid. Not perfect but likely enough to do cleaning and lubing.

Step 3.

The markings of the locking screws are visible on the threadings on the barrel. Choose one of each sets and mark the spot somehow on visible surface. When screwing the sleeve and glass assembly back, it is possible to tighten them a bit over the original spot. With the markings You can find the original positions. The rest is obvious, just remember to loosen the locking screws a bit before screwing the sleeve and the glass assembly back on.

If this is not enough, I guess You have to remove the tripod mount. There's probably some more locking screws beneath, but I haven't gone that far.

Lloydy · Expire: 2022-01-01

Some of the pictures are still in this topic.

http://forum.manualfocus.org/viewtopic.php?id=3880

and as Marcus has said, the felt dust seal is the biggest cause of focus stiffness. I've soaked the felt in silicon oil - it's better, but still not as free as I'd like.

philslizzy · Joined: 07 Aug 2012 Posts: 4749 Location: Cheshire, England

any luck?

marcusBMG · Joined: 07 Dec 2012 Posts: 1298 Location: Conwy N Wales

(belatedly catching up with this thread thanks for responses)
Thanks for detail Gamera I think your directions match my account here.

I had actually already found that thread Lloydy, and I think it is misleading. The pics posted showing the interior of the mount end show yellow notched parts at the bottom. I am pretty sure that these are not to unscrew the assembly but are the helicoid guide rails. One of the notched rings lower down IMO is what needs to be unscrewed ...

At the mo the tair is in the projects box awaiting the manufacture of a custom spanner. Thought the silicon suggestion is worth a try thanks for that. actually I suspect s/o has previously tried a bit too much wd40 Sad

Ramon · Joined: 01 May 2007 Posts: 71 Location: Kent, UK

Marcus, check your thread in the Pentax forum because I have just replied to that one.