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Repair and Restoration Pentax 67
Posted By: Aristote, 03-19-2020, 03:12 PM

Hello !

Happy owner of a Pentax 67 from 1989, I wanted to perpetuate this fabulous system by buying a second case. However, to my dismay, I noticed the frightening increase in its rating, a consequence of the fashion effects and Youtube videos of Hipsters lend to all possible promotions to get views.

A solution then came to my mind, buy a defective case and refurbish it. We do it well with vintage cars, so why not with the boxes?

Current technological and production means allow us to design replacement parts at a relatively democratic cost. however, keep in mind that the more the base is damaged, the more difficult the restoration will be. For ease and saving time, we will leave on a drinking basis. I will detail the process, prices, tips and other information in order to have a complete resource that can be used by everyone. You have to keep in mind that all the will in the world does not replace the training in automobile mechanics that I acquired as a teenager. Do not venture into this kind of operation if you do not have a minimum of experience in the matter.

Here's the beast:

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A 1989 Pentax with a decent cosmetic condition, the shutter seems to be blocked. The whole thing came back to me at 80 euros. Before starting the operation, it is preferable to draw up specifications with a specific objective to achieve. My first idea was to redo a complete painting of the chassis, it will be justified or not according to the state of the painting. The brass upper parts are not subject to corrosion, but the steel elements like the rear door yes. Therefore, it would probably be a good thing to redo a complete body. A Hammeritte type lacquer with baking seems to me a good starting choice, however I must inquire about the resistance of the product.

I based myself on the work of Oriu, an incredible French forumer who repaired his Pentax too. Without him, I would not have started this journey.

---------- Post added 03-19-20 at 03:28 PM ----------

Well, I had already prepared the tools:

- Tweezers with magnifying glass for small assembly parts.
- A set of gauges to calibrate the spacings.
- A caliper for measurements to the tenth of a millimeter.
- A micrometer for measurements to the hundredth of a millimeter.
- Precision screwdrivers.
- Trichlorethylene.
- WD40 (penetrating and protective for electrical contacts).
- A syringe loaded with lithium grease.
- A syringe loaded with synthetic engine oil.
- Disposable nitrile gloves.
- Various consumables.
The service manual not to be silly and go blind:
https://www.manualslib.com/manual/99867 ... x-6x7.html

I recommend consulting the manual before each disassembly step in order to have a mental diagram and know which direction to go. I will reference the pages during the steps so that you have a precise view of the operations, these will be highlighted in red in the parentheses.

The service manual tells us that I need more specific tools (page 108), I will manufacture them according to the disassembly, because I need to visualize and measure the spacings for machining ( Caliper and hard tweezers can make the job too).

First, we will prepare the disassembly of the screws by pouring a drop of WD40 on each. To facilitate its application, we will incorporate the WD40 in a pipette bottle, the dosage will be more precise with no risk of splashing. The WD40 is a powerful penetrating oil with great infiltration power. In fact, over time, the screw threads oxidize when you never disassemble them and it becomes difficult to extract them without ruining the screw head. I recommend waiting 30 minutes for the product to take effect.

Once the time has elapsed, I begin removing the barrel of speeds, the view counter, the cocking lever, the upper covers and the ornamental plastics (these are brittle and I do not exclude 3D printing with acetone smoothing).

A part was broken in the mechansim. I guess that he felt, the piece had traveling in the mechanism and bending the shutter gears.







I started my journey of chassis / cage decoupling, but not obvious at all! As specified in the service manual, the coupling elements of the arming mechanism must first be removed from the cage. I started with what seemed to me the simplest, point 2 which includes the elements C8 and C9. Once the two screws removed (one long and one short), it is necessary in addition to that to extract the circlip LW24 which holds the control rod of the mechanism, otherwise the extraction is almost impossible. To do this, a flat screwdriver and patience, because it is badly placed and the place is cramped. Furthermore, once deposited, it is housed in the mechanism…





We then go to the mechanism which does not really reassure me and which I left fallow ... First C27 with its two screws. The C25 shouldn't be a problem. On the other hand, I am less sure for C23. Indeed, its retaining screw has an ugly head and requires specific tools



---------- Post added 03-19-20 at 03:31 PM ----------

We move forward !

The box is detached from the cage and I will be able to try to understand where the curtain is blocked. New on this model compared to the old one, we notice that the ribbons of the curtain are now in fabrics and no longer in plastic. One of them has slightly derailed from the roller and I wonder if the tension is correct, because it is against, but moves easily. Precision for the head of screw C23,





I had to remove it delicately with a pliers with fine nozzle, because, I did not succeed in machining a satisfactory tool. However, the tightening torque is not high, everything went well with a little patience and a lot of WD40 it came easily. You will still need a correct tool for reassembly. Case to follow !

---------- Post added 03-19-20 at 03:35 PM ----------

As we can see in the photo, the pinion axis has completely deflected backwards! Which explains why the cam was twisted ... The solenoid doesn't seem to release the cam either, I think at least. I have to study how it works to understand its logic ...
As with the impossible, no one is required, I will dismantle everything and straighten the axis and we will see then! I would have preferred a badly positioned but good spring…



I left the cage for the end and decided to devote myself to the mechanism of the body. Indeed, it had a problem and comparing it with my functional box, I found that the winding mechanism was stopped ... No choice but to dismantle everything, we will take the opportunity to clean all the gears and lubricate all with mineral engine oil and lithium bearing grease. The latter does not disintegrate and resists high pressures, moreover it is sticky and allows the parts to be kept in their locations.

https://nsa40.casimages.com/img/2020/02/15/200215063424356470.jpg

I had a problem with the disassembly of the C73 screw which serves as an axis and support for the O-C34 plate because of a recurring problem, the inability to machine a special screwdriver. Good old method of pliers, screwdrivers and WD40 with caution, of course. Although it is still drinkable, I think I would find out to possibly redo one with a milling turner in pattern making ... To see if the game is worth the effort. Ah yes ! In my runaway, I dismantled everything without taking the time to note the locations and functions of the mechanism. So I'm going to put it all together with the exploded view and common sense. The reassembly will take time, I think ... There is a foam to replace which takes care of the maintenance of one of the springs on the chassis, it is visible on this photo.





---------- Post added 03-19-20 at 03:38 PM ----------

First level raised with difficulties adjusting the cams. Indeed, the springs between the supports and the cams (1 and 2) must be perfectly adjusted under penalty of having trouble tightening. To be more explicit, they do not adjust on the axis, but on the cam and loosen when moving.

You have to arm yourself with a lot of patience, skill, and a little luck to properly position the springs ... I ch ** ma ra ***! But it's done! Finally I hope it is mounted correctly, we will see when the mechanism is reassembled.

If I understood correctly, when we close the back, a protrusion pushes the cam 2 which in turn connects the worm of the view counter to the notched wheel of the upper part (0-C34). However, I can not grasp the logic of the cam 1 and the rewinder locker which is housed at point Z. I also still have a little trouble on the connection point 3, its positioning makes me perplexed …

I will also look for a method to correctly align the star wheel of the 0-C34 axis with the lower cams.



---------- Post added 03-19-20 at 03:41 PM ----------

We had seen that the pinion axis was deviated from its axis because of a possible fall or forcing of the mechanism (I don't always know not). In both cases, it was not won ...

I carefully dismantle the screw that fixes the group of toothed wheels in order to extract the pinions one by one. Without adequate tools, I use the same method, screwdriver and flick counterclockwise, the tightening torques are very low and therefore the screw comes easily. And there I see that the axis is badly bent.
Luckily, brass is easy to work with and the straightening method is simple, a small pliers with insulation around the teeth so as not to damage the axis. The brass is soft and the thread fragile. We will also remember to put the screw back on the net so as not to damage it during the folding phases. We grasp the axis and we proceed by blow, millimeter so as not to risk breaking the part. We especially take our time in this kind of operation.

For the anecdote, I remember one of our school visits during my mechanical years at Herstal Group where a barrel straightener officiated, he had the particularity to do it with the naked eye without measuring instrument, it was fascinating and it inspired me to do the same with this beautiful Pentax 67!
Here is the straightened axis:



I apologize for the round trips on the different parts of the box, but I like to roam in the landscape and follow a precise frame quickly bores me ... See you soon !

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03-19-2020, 03:57 PM   #2
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It looks like an adventurous undertaking. I didn't realize there was so many gears, cams and linkages under the skin. The link to the manual is broken, btw.
03-19-2020, 03:59 PM - 2 Likes   #3
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Continuation of the operation on the cage.

After having straightened and cleaned the axis and the supports, I also made a small inspection tour and I noted that foams were present on the points in photo. In addition, I took the opportunity to clean, oil and grease the mirror mechanism which was relatively clean, but whose old greases had disintegrated over time. Classic cleaning with 70 ° alcohol and cotton swab on the shafts and cams. We will avoid touching the contact blades as Oriu told us, at the risk of distorting correct operation. Then, we will grease and oil the friction points with a micro brush and syringes loaded with consumable while following the instructions in the service manual. Pentax uses different types of grease for its maintenance.



During the calibration of the shutter, I noticed that the locking lever was not in contact with the pinion of the first curtain, so I had to straighten the axis again to make it coincide. To be more precise in the operation, I measured the spacings with a set of gauges.

The first measurements gave:

0.60 mm => 1st curtain
0.30 mm => 2nd curtain

Which is a huge difference for such small parts. Lest the game worsen over time, I continued the recovery by going in small strokes on a dozen interventions (you have to go smoothly, it's brass).

The final measurement:

0.40 mm => 1st curtain
0.30 mm => 2nd curtain

We are in something more acceptable now.



The curtain was too far of the edge on the point 2. If the curtain is too far, when you cocking the shutter, the gear can't take the shaft correctly and problem coming.

We are moving slowly, but surely!

I repositioned the upper plate of the arming mechanism (0-C34) successfully, I think, the rest will wait while waiting to reassemble the cage on the chassis. Indeed, it will be easier to couple it this way.



I also started the repair of the prism coupling chain with the housing. As we can see, the spring is completely destroyed by inappropriate tension. Following an aberrant fragility of the original coupling chain, I decided to replace it with a 0.25mm diameter nylon thread. If you need to do this, I recommend replacing the chain completely with this type of wire. It is much more resistant and stable in drive pulleys. However, the spring is so destroyed that it releases the wire each time it is mounted. I will come back to this at the end of the process so I have just changed the foams for now.




There is a problem with the frame counter dial. I dismantle the part to see the problem inside. The spring was gone on the wheel, so I re mount it, but when I turned the wheel, the spring was destroying :/





I was lucky cause Remy on the Forum sent me new spring of Kiev 88 and VHS player ! Thanx so much again <3

After reassembling the mechanism, I encounter the same problem as at the beginning.

The mechanism arms the shutter and the mirror, moves the film to the first view, stabilizes it, the shutter exposes the view. Then, the successive armings only arm the mirror and the shutter, but the film does not advance further, it remains on the first view counter does not advance further.

Observed facts:

- The view counter does not reset when I open the door. I must remove the O-C33 plate and therefore the O-C24 cam so that it returns to its starting position ( fig 1 ).

- On my functional unit, I note that when I rotate the winding pin C48 in the loading direction, a rattling occurs by the jump of the pinions C43 and C44 ( fig 2 ). Clicking that there is no faulty case.

- The friction spring in C118 ( fig 3 ) seems to no longer play its role. When I removed the film, it comes easily in the blocking direction by pulling it. I had inspected it briefly before reassembly and it seemed to work at the beginning ...

I suspect the friction spring, but why does it cause the film on the first view if it is broken ?



My mistake !

It was indeed the friction spring located between the winding lug and the transmission gear. It allows the good winding of the film by forcing the direction of it in one direction only. We see on the video that the film no longer advances if we maintain a slight pressure at its base.


Re re re re complete disassembly of the mechanism, but not going any further this time. I had to put down the first plate which contains the spring, but the screw which holds the assembly is very soft and did not hold the shock. I'm going to have to work on a way to extract it, I will run a new one later. First bath in WD-40 to facilitate the process, then I will think about the best way to extract this spring dirt C118 with a special tool.



After 48 hours of WD40 bath, it remains tough this little screw! I was surprised by the amount of dirt that bleed from the cavity, probably a mixture of grease dust ... We can see the state of the WD40 on the attached image.

Disassembly was done with a rectified screwdriver and a caliper whose chevron spouts adapt perfectly to the gear. Unfortunately, without success : cry:

It will leave for 48 hours more in the pool, it will give me time to machine a more precise tool to avoid the nonsense that could occur, the caliper is quite large and does not allow maneuverability optimum. This small room makes me particularly anxious ... The composition of the tray does not reassure me at all ... To be continued !



Not without difficulty, I finally dismantled the group. The thread is reversed and the thread lock was present which did not facilitate its removal. I had to rectify and enlarge the impression of the screw head. The tightening torque was really strong and the screw material quite soft, which does not help of course.

The spring appears to be in good condition. The only explanation would be that a fatty substance accumulates in the cavity and interferes with friction. I cleaned everything with a fine brass brush followed by a Trichlorethylene bath. I noticed a lot of dross coming out of this small group, it was quite impressive ... If the problem persists, I do not see where the failure could come from ... Cross my fingers !



To be continued...

---------- Post added 03-19-20 at 04:00 PM ----------

Hi Tuco !

Here you are : ASAHI PENTAX 6X7 SERVICE MANUAL Pdf Download.

---------- Post added 03-19-20 at 04:08 PM ----------

So !

The spring of counter dial frame is repaired with new spring.


The Camera is repaired but not completly, the shutter work and the mirror too, but the transport film not. I'm gonna check this part with the friction spring.


Stay tuned !
03-19-2020, 10:07 PM   #4
mlt
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Awesome!!

03-20-2020, 03:59 AM   #5
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WOW!!
03-20-2020, 08:21 AM   #6
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Nice. Seeing that camera in hand makes one realize just how huge it is. That actually makes me want one more. I wonder if I could set one of my auto 110 cameras in the bayonet mount?
03-20-2020, 09:07 AM   #7
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Nice work.
03-20-2020, 09:21 AM   #8
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Thank you for your compliments!

He remains capricious ... But he returns from darkness so it's normal. Folded axis of curtains, detached spring, serviced and folded control cam, etc.

Lots of little things that make a big deal of trouble ! I'm not out of the tunnel yet...

This an exceptional camera ! I prefer it compared to the RZ which is also good, but its modularity which is a big quality becomes a big defect in my hands (slower loading of the film, bigger, different ergonomics). If I have the opportunity to find a third Pentax, I will take it without hesitation !

03-20-2020, 01:28 PM   #9
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Impressive! Looking forward to next part of the story (... and the camera lived happily ever after
03-20-2020, 02:33 PM   #10
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QuoteOriginally posted by pentageek Quote
Impressive! Looking forward to next part of the story (... and the camera lived happily ever after
I'll do whatever to keep him alive again !

I have two screws to machine before returning to the Pentax. I am trying to repair this camera without cannibalizing another Pentax 67. I assume that they are repairable and that putting them in the trash for donors is an aberration.

Therefore, it takes a little more logistical time. I am going to test painting, but with COVID19 the paint stores are closed.
03-24-2020, 03:32 AM   #11
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Thank you very much for your contribution! I linked this one to the broken Pentax 67 Repair (missing pictures), because the search still gives the other out more easily. I hope to see your 67 soon up and running again!
03-24-2020, 04:58 AM   #12
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Hi Wildmo !

Thanks so much for linking ! I hope so too ... With the Covid19, the process is a bit halted so ...

I resume the operation as soon as I can
03-29-2020, 01:36 PM   #13
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Well !

With containment the restoration is slower, but I finally wanted to try the paint and started sanding the plates below to redo a paint. The Rubicon is crossed. The upper ones are in good condition and I will not touch them. The former owner used to use a dedicated handle and caused friction damage.





In addition, I give you a little tip if your battery compartment is lower than the protective plate. Just place a shim and bend the leaf springs.



04-23-2020, 02:18 PM   #14
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A little new in the progression !

The original caches have lived a lot and are likely to spoil the paint job .... I therefore decided to design new protective caches for the Pentax 67. As you know, I decided to repaint the rear door rails and the brass soles. I will not touch the top covers because, as Oriu pointed out, they are in good cosmetic condition.

So I started modeling new caches which I will have 3D printed then smoothed with acetone in order to obtain the original gloss of the old polycarbonate sheets. I would have liked to machine them out of steel or aluminum, but the CNC costs in private are completely outrageous ! I could try to see if the digital milling machine is accessible at my old college. Whatever happens, 3D printing will remain the preferred solution.

I tried to reproduce the dimensions and dimensions of the right side cover as faithfully as possible (front view), there will surely be several tests to do and small corrections here and there, but the bulk of the bulk is done! I purposely excluded the holes for the flash connections for three reasons:

1) I never use flash.

2) The flash at 1/30 of the Pentax, hum hum ...

3) It looks prettier like that.

It should be noted that in the worst case, the holes may be machinable using a few drills ... We always keep an option.

The structure has been reinforced with an addition of material at the edges in order to increase the resistance of the cover and to leave a margin for drilling the fixing holes. I added two cavities of 5 mm in diameter so that the screws of the ratchet can accommodate without bulging the plastic.

Here are some illustrations while waiting for the modeling of the other parts:





I do not think to make the plate above the back which is in good condition. On the other hand, the lower cover would also need to be redone, but modeling it is sport ... Stay tuned !

PS : Example of final result 3D print smoothing

05-01-2020, 04:28 PM - 1 Like   #15
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I finally launched the modeling of the bottom plate, it wasn't easy on Autocad, but with some tutorials and a lot of patience everything is possible !

I will obviously make the files available for free download, but I must first check if the measures are well suited to the body.



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