Hasselblad Film Back: Disassembly, Cleaning, Lubrication

Intro: Hasselblad Film Back: Disassembly, Cleaning, Lubrication

NOTE: This instructable describes the disassembly procedure for the older type C backs. However, with a few differences (such as positioning of screws etc) the same procedure also works for the newer A12 and A16 backs.


Some of my Hasselblad film backs don't like cold temperatures. They cause all sorts of problems, overlapping frames, locking up, etc. This is common due to old grease and lubricants gumming up inside, and fixed by cleaning and lubricating the internal film back mechanism. A standard service job, but quite expensive when done by a professional -- so this time I decided to try it myself.

I armed myself with my (expendable) old C16 film back, a service manual (found on Scribd, unfortunately for A12 & A16 backs only, but it still provided me with enough leads to do this on my older C16 back), a few tools... and a fair dose of patience.

Tools used:
Jeweler's screwdrivers
Pointy metal tweezers

Materials:
Cleaning:
Q-tips, degreaser, Isopropyl alcohol
Lubrication:
For the orthodox: Isoflex Topas L 32 (grease) and Isoflex PDP 48 (oil) -- as recommended by Hasselblad.
For the home tinkerer: use what you have, in my case lithium grease and sewing machine oil. It works.

Time needed: 1-4 h -- but add countless hours if you drop a screw or a spring on the floor...

DISCLAIMER: This worked for me, and it may or may not work for you. I am a tinkerer (if that), not a mechanic -- nor am I a Hasselblad expert. This is not the official Hasselblad procedure for this job, I worked this out for myself. If you decide to try it, great, but I will not be held liable. :)

STEP 1:

Start by peeling off the circular leather piece on the back's film advance wheel.

Unscrew the fastening screw that was hidden behind the leather. I used my pointy tweezers as a small spanner for this.

Remove the advance wheel -- you may need to pry it off, it can be a tight fit.


Peel off the leatherette on the sides to gain access to the fastening screws.
NOTE: On the newer A12 and A16 film backs, these screws are located under the leatherette on the side panels instead!


Although not strictly neccessary I decided to remove the leatherette altogether, so as to not have it flapping about during the rest of the procedure.

STEP 2: Remove Light Seal, Clips and Spring Rods

Before removing the back cover:

Remove the 9 screws surrounding the film opening. Note that one screw is longer than the others, it is marked blue in the image. Make note of its position.

With the screws removed, carefully lift off the "frame". Use the darkslide as an aid to loosening it if needed.

Under the "frame" you will see the light seal. Remove it. If yours looks worn and old, have a new one ready for the reassembly. Find new (3rd party) seals on eBay, or do as I do and make your own from old exposed film and thin self-adhesive foam, folded and cut to size using an old seal as a template.

Lift out the two black spring rods, and the metallic "clips" (note the position of these).

STEP 3: Remove Back Cover

Unscrew two screws (note: these are longer than the other three) on one side and three on the other side. Technically you don't need to do this in order to remove the gear cover. However, in order to actually get the gears out for cleaning it has to be done.

NOTE: Again, on A12 and A16 backs these screws are under the leatherette on the protective side panels.

STEP 4:

Remove the middle screw from the inside (marked red).

STEP 5:

Lift off the side panel.

Then remove the inner plate from the inside. (This is actually why you removed the side screws on the cover: the cover may need some prying out in order to get this plate out.)

STEP 6:

Unscrew the three screws holding the covering plate. The plate is a press fit, and may require a bit of persuasion to come off. Push down (using your screwdriver or similar) on the gear rods at point B, C and D, making sure they come loose. Especially at point A the fit is tight -- you will need to push down hard on the protruding axle as you pull on the plate.

STEP 7:

With the cover plate off, the first gear to come off is the big one (marked E). Everything is interlocked at this point, so you'll need to push the rod out in order to remove the gear (see next step).

STEP 8:

Working from the inside, push the rod for the big gear (marked E in previous image) out using a pointy object.

STEP 9:

With some careful wiggling, the gear should come out.

Try not to pop out the gear in the lower right (E), or you're in for a surprise: the cog is spring loaded underneath. Use a small screwdriver or similar to hold the spring in the gear as you slowly remove the gear. If you don't take great care when removing that gear (F in previous image), the spring will pop out with (SPROINGGG!) and tangle itself. It's no disaster if it does pop out, but it means you have to spend extra time and patience to untangle it and refit it into the gear. It's not difficult: place the spring "hook" into the slot (as seen above), and gently wind the sping back while turning the gear.

Note for reassembly later: (ADD PHOTO)
slide the spring loaded gear on to its washer (black disc thingy in the next photo). Use a gentle rocking motion when sliding it in place, all the way down. The washer has a small stop that the spring will catch once in place, allowing the spring to be tensioned. Once in place, tension the spring by rotating the gear (don't remember the direction, but it's obvious as the spring only tensions one way) and holding it in place while replacing the big gear (the one removed in previous image). There's probably too much tension and too little tension here, and I have no idea what Hasselblad recommends. I tensioned it something like 1.5 to 2 full turns, it worked for me. Too much tension and the nylon stopper will wear out. Too little tension and the big gear (that interconnects to the camera winding) will not spring back into its correct position.

STEP 10:

The big gear your removed in previous step is actually two gears sandwiched around two spring loaded stoppers (and a removable rod).

If you separate the gears (and you should if you intend to clean these parts), there's a trick to putting them back together later for reassembly: insert the rod into the lower (bigger) gear, and slide the top gear on to the rod. Then, using a thin screwdriver or similar through one of the holes of the top gear, slide the stoppers outward until the top gear clicks down into place.

Simple, but it took me a good while to figure out... Then again, on some backs these parts just click into place without effort. Your mileage may vary!

STEP 11:

Remove the frame counter plate, two screws. Make a note or a photo of the position of the counter plate, for reassebly later.

STEP 12:

The white L-shaped part is the infamous nylon stopper, that tends to get worn out in backs that have seen extensive use. It may need replacing, but spare parts are hard to source. It should be possible to replicate one by hand, if suitable material is found. The material looks and feels like HDPE plastic.

Then, basically remove everything else. :)
Uscrew and unhinge the linkage arms, springs, wiggle out gear cogs etc, it's a bit fiddly but pretty intuitive. See attached images.

STEP 13:

Stripped!

Yes, there are a couple more parts that could be removed, but I wouldn't bother. For cleaning purposes, this is where I would stop. 

Clean and lubricate:
Immerse all gears, springs, linkage arms etc in a degreaser, and let them sit for a good while. Rinse in isopropyl alcohol. Short of Isoflex Topas L 32 (grease) and Isoflex PDP 48 (oil) that Hasselblad recommend, I opted for what was available to me: lithium grease and plain sewing machine oil. I put a minute amount of grease on gear teeth, and sparingly applied oil to other moving parts and joints.

Reassembly is, I'm afraid, simply a reversal of disassembly. ;)

Comments

[rulnacco]

This is a very useful guide, and I used bits of it to help me refurbish a C12 back--I'd already done several A12s, and was familiar with those. However, there are a few things that I found the author could have expanded upon the necessity of, and if you do them as described (you don't have to in every case), you will create extra work for yourself. And there is one thing he neglected to warn against--which he may have been lucky not to have experienced himself.

Here are the things I would recommend be incorporated--and I would advise you to follow--if you use this guide:

(1) You do not have to take off the film advancement/winding wheel in order to access the gears for inspection. The hole in the cover plate itself is large enough you can take off the cover to examine the interior (to see if you actually *need* to do any cleaning/repair) without removing the film winding wheel. Now, if see you are going to have to do the rest of the procedure outlined, you *will* need to take off the film winding wheel then, as you have to do that in order to remove the bridge plate and get at the gears/springs/levers themselves in order to remove and clean them. But I wouldn't do that right away; I'd wait to see if I really was going to need to do some cleaning to the back before I did that bit.

(2) You probably do *not* have to remove the leatherette covering the entire shell of the back, or the screws underneath it, to remove the cover on the winding/frame counter side of the back (where the gears are). None of the five screws he mentions above actually hold the side cover on--it is held in place by some of the nine screws in the attachment/film frame plate, and the single screw inside the back that he indicates.

Taking off the leatherette is easy but involves a considerable amount of time and work to clean the old adhesive off and put it back in place, so don't do that unless you're actually replacing the leatherette with new. And pulling out the five screws holding the shell can lead to other complications, when you normally don't have to take them out at all. (He recommends that you take off the leatherette and the shell screws to make it easier to pry off the side cover if it's difficult to remove; that is true, but you *probably* won't have to do that. Using your fingernails, or a thin-bladed screwdriver, you *should* be able to pop off the side cover without going to all the extra work of removing the leatherette and the five screws.)

In Step 8, he shows that you have to push the pin holding the double gear in place out from inside the back. If you do that, you *do* have to take out the screws holding the shell in place, as there is a plate inside the back you have to remove in order to get at that pin. But I've never found it necessary to do so--just take off the top gear of the two gears, and there should be enough of the pin showing that you can grip it and pull it out with your fingers (wiggling the bottom gear which is still on the pin helps) or you can do so carefully with needle-nosed pliers. *If* you can do that, you can avoid the hassle of removing the shell screws and the plate inside the back.

(3) Please follow his advice not to let the gear he indicates spin out of control, which could cause the spring inside--as he graphically describes--to pop out and maybe fly across the room. But if that does happen, this spring is relatively easy to replace inside the gear.

However, be very, very cautious about taking the frame counter wheel off, and *don't* do it unless absolutely necessary. Underneath the plate with the frame numbers is another, similar spring--but unlike the first spring, the one under the film counter plate is the spring *from hell*. Mine popped out, right in my face. And it took me literally *hours* (and lots of yelling and cussing) before I finally came up with a technique to wind the damned thing back inside the gear properly--and get it to *stay there* while I was trying to put everything back and re-tension it. It was actually pretty simple, once I discovered, *through painful trial and error and many explosions of the spring back out of the gear, including multiple instances of it flying across the room or winding itself upon itself like spaghetti* a reliable and fairly rapid (if careful) method to wind it back in and secure it. Spare yourself this torture.

(The spring I am talking about is shown in Step 12, the middle photo on the right. Hasselblad completely changed the spring in the A12 backs possibly I think because they are such a pain in the butt to assemble on the C12 backs.)

If you *don't* have to pull out the frame counter wheel--and, really, you shouldn't have to do much/any cleaning there, and only a little lubrication--do not do it. If you do pull it out, you'll have to re-tension it, and that's when you may have to take off the frame counter plate in order to get the spring through the slot in the axle that secures it (see 4 below). And doing so potentially opens a portal to the nether regions--you have been warned.

(4) Speaking of the frame counter wheel, be careful of the phrase in this post to just use oil to get it to spring back properly. As I mentioned above, if you've taken it out for cleaning or any other reason, you have to re-tension that evil spring inside it--if you just stick it back on, it won't pop back correctly. (The author does mention this in the caption to a photo if you click on it, but doesn't give much detail about how to do it.) If you are lucky, you can do that without taking off the frame counter plate, and potentially releasing that spring.

If you just slide it on (more about how to do it properly in a moment), and you turn it to the maximum it will rotate--there is a stop that prevents it from rotating further--then it will only spring back weakly. What you have to do is slip the whole wheel back on partway, making sure the spring engages with the slot on the axle but keeping the counter wheel above the stop, and then give it a full turn to wind the spring a bit. Now push it on all the way (you may have to turn it back and forth a little until you find the orientation where it will slide on completely), and you should see that it springs back enthusiastically afterward.

The difficult bit is this: if you look into the hole in the center of the counter wheel, you will hopefully see a bit of the spring sticking across the hole. That bit has to fit into a very narrow slot cut into the axle, which holds that end in place so it will take tension. If you can see it, and you have some long, thin tweezers, you can probably insert the spring into the slot while putting the counter wheel back on. If that part of the spring slides up into the wheel when you're doing so, so that you can't see it anymore (which is what happened to me), then you will need to take the frame counter plate off to get it into the slot--that's where you're going to run into the problems I dealt with.

In that case, as I mentioned above, you have to wind the spring back into the gear that lies under the frame number plate, very carefully--so that it doesn't pop back out, mine *really* wanted to do that *constantly*--and then insert it partway onto the axle, making sure the spring goes into the slot, Then before trying to push it on any further, *carefully* put the frame counter plate back on and screw it in place--that will keep the spring in place as you tension it, and then push it back on all the way. When you're putting the frame number plate back onto the gear, make sure you put it on the right way around--if you look at the small teeth on the bottom of the gear itself, you'll see they don't go all the way around, there is a gap. The 4 on the frame counter plate lines up roughly with the center of that gap.

Be careful when screwing in the two screws that hold the frame number plate on. You should be able to see where in the slot they should go, as there will be marks from their original installation. They need to be in securely, so the plate doesn't move around, but don't put them in *too* tightly, or their edges will try to go through and under the slot. And don't screw one in all the way before inserting the other--that will cause problems with the second screw. Put them both in, just enough so they don't fall out, and alternate tightening the two screws so that the frame counter plate stays level and you should be able to gently snug them up well without putting one entirely through the slot, which is not good.

(5) You may need to replace the nylon stopper, as mentioned--Hasselblad still sells replacement pieces, but there are sellers with 3D printed versions on eBay at reasonable prices that appear to be just as good. However, unless your back has been extremely hard used, you probably won't have to do that. My back showed lots of use by its cosmetics, and the lubricants were all gummed up. But the nylon stopper looked fine.

However, whenever you open up this back, it *is* a good idea to replace the light trap where the dark slide is inserted, as the author touched on. This can become worn/torn, or the foam can become too compressed to be effective in blocking light. Hasselblad generally recommends you replace these frequently, particularly if you leave the back stored with the dark slide in, which compresses the foam. Hasselblad also sells this part still, too--but there is a well-known seller on eBay who provides a suitable replacement part (and great directions) at a considerable savings. I have replaced the light traps in my backs, and for several customers of my local second-hand camera shop, with those products and they seem to work fine.

If you do shoot infrared film, I would recommend you get the genuine Hasselblad item; the eBay version and the author's home made version is made of only mylar or other plastic, whereas the official Hasselblad version also has a metallized foil strip attached, which *may* be there to block IR from entering through the slot for the dark slide; the mylar on the bootleg versions will block visible light, but I'm not 100% certain it's impervious to IR.

One final (at last) general note: When doing *any* of this, do it all completely over a table top. Preferably with a white towel/cloth or a green cutting matt that will catch and reveal any small black screws you've dropped. If you drop anything on the floor, particularly if you have carpet, finding it may be a nightmare. What I always do before working on cameras is to vacuum thoroughly the the area around my workspace, and completely empty the vacuum bag/debris chamber. Then if I do drop something on the carpet and can't find it, I can just run the vacuum cleaner over that area, and it should be pretty easy to find the bit in what's been sucked up (a magnet may help find tiny metal bits among dust, hair and dirt). The less junk that was there before starting, the easier it is to find. Trust me, this has saved my bacon *several* times and prevented some piece of gear from becoming useless because of a missing tiny screw or spring.

Otherwise, this is a very useful and accurate guide to servicing C12 backs--and much of it also applies to the more modern A12 backs. And it is much appreciated!

[RodrigoA160]

hello! how did you remove the magazine film crank at the beginning, just to expose the sprocket as seen on the first image? thank you in advance?

[Magastrom]

If you have a real crank you have the A12 back, this is for the older C backs. On the A's, you remove the crank itself by pushing the little pin out on one side, but I believe the crank assembly is secured into the cover from the inside. Good thing is you probably don't need to remove it as there is no center screw as on the C backs, meaning the cover should pull right off with crank and all once you've done the other steps.

Again: this instructable is for version C mags, some things such as the exact position of screws etc under the leatherette may differ in the A mags (my guess is it's about the same).

Hope that helps,

Magnus

[CristianH32]

Bravo, thanks for documenting this. I rebuilt my A12 magazine today!

[olaf.ttngr.3]

you are a god amongst men. thank you.

[amandaghassaei]

great photos and documentation! but what is a film back for?

[Magastrom]

Well, in 2012 I suppose that is a relevant question! :)

There are many reasons why one would still want to shoot film in the age of digital cameras, but I won't go into that here.

To answer your question: the classic Hasselblad film cameras are modular in construction: the camera body is the core module, to which one attaches a lens, a viewfinder, and a film back. The film back attaches to the back of the body (hence the term back) and holds the film. These film backs are generally the weak point of Hasselblads, but they're actually fundamentally sound, its just that they require expensive servicing once in a while to function well. This instructable aims to help Hasselblad owners do that themselves at literally no cost.

[sath02]

Well, in 2012 not so many people know what is the camera body of "Hasselbald" really look like without seeing the picture of it!
So seeing the picture of the film back installed on the camera would explain itself to non-Hasselbald owner nicely too.

[Phil B]

I once took apart a portion of a slightly less expensive film camera. I did get it back together again and saved myself a bundle of money. Plan B in the event I could not get it back together would have been to take the pieces to a local repair guy and say, "Yes, I took it apart. Now I am going to pay you to put it back together." If one is very careful, there are many things a handy owner can safely do to his camera equipment.