Hasselblad Back (pre-A12) Repair

Hello.

My Magazine 12 developed a problem where the backwards turn of the winder was not resetting the film counter. I thought this might be a useful starter project for a clean and lube. It has turned into a bigger project.

Problem 1: a seized/stripped screw on the outer shell. With hindsight, I might have been able to release the inner plate with a but of bending of the outer shell, but that might have made things worse. Anyway, I've drilled the screw and now need to find somewhere with a precision drill press to drill out what remains of the screw and retap the hole. I'm in Melbourne, Australia. Does anyone know who might do this sort of work? I expect that I'll have to put in a slightly larger screw.


Problem 2: After removing the outer shell to reveal a whole bunch of black dust fell out. There's far too much of it to be just accumulated gunk, so I'm guessing that is the remains of some light sealing material. There is a strip of light seal in the service diagram for the A12 which looks much the same shape as the dark slide light seal foam, except without the backing. Any suggestions of what to use?




...and this is before I've even got the actual problem. A Quick Look at the gears and everything is there, so I'm, hoping that a clean and lube might actually fix it - it's all pretty old and gunky in there.

Thanks

Warm regards, Geoff

Geoff Bartlett said:

A Quick Look at the gears and everything is there, so I'm, hoping that a clean and lube might actually fix it - it's all pretty old and gunky in there.

Click to expand...

It probably will. Go easy on the lubrication. It's too easy to put too much. I cleaned one of mine and used less than a drop of oil to lubricate and it works fine, now (had the same problem).

Problem 1: you can take a small drill bit and in essence hollow out the existing headless screw. Looks like you have a nice center divot. Use a bit about 2/3rd diameter of the screw? Then collapse the outer 'tube' that remains inward and pull/push it out of the way. Or you might even be able to take a small screwdriver, jam it into the hollow, and back the screw out.

You might need to go to wider diameter bits. Although this isn't 'best practice,' screw threads do have a little excess material and will work fine in most case if your drill bit reduces them slightly. And you don't need absolutely perfect threads at all points in all directions. A little nick here, reduction there... This isn't a life or death assembly (oh geez, did I just way that to a Hasselblad guy?? my apologies. yes your camera is amazing!!! A little light duty thread lock might help reduce any anxiety if you have gone into the threads themselves a bit.

Problem 1: drill a small diameter pilot hole and use an easy out to remove the screw. An easy out is a conical left hand threaded tool designed for exactly this type of problem.

I've had some success with removing screws as small as ~1 mm with screw extractors, similar to types used for wristwatch repair. But if it's fused into place due to corrosion, you might wind up having the drill it out as best you can. The steel used for these tools is hard and fairly brittle, but I can generally get a few uses out of them before they become toothless. I chuck these into a pin vise.

Older Hasselblad backs have a plastic bumper which serves as the counter's zero-stop, but over time, the tip can break off, resulting in the counter resetting to some random, unhelpful position. Replacements can be home-made. I've had success using polyethylene scrap from a milk or juice container.

Don_ih said:

It probably will. Go easy on the lubrication. It's too easy to put too much. I cleaned one of mine and used less than a drop of oil to lubricate and it works fine, now (had the same problem).

Click to expand...

Thanks. Good to know

And I thought the hard party of this job was going to be dealing with the gears.

Dan Daniel said:

Problem 1: you can take a small drill bit and in essence hollow out the existing headless screw. Looks like you have a nice center divot. Use a bit about 2/3rd diameter of the screw? Then collapse the outer 'tube' that remains inward and pull/push it out of the way. Or you might even be able to take a small screwdriver, jam it into the hollow, and back the screw out.

Click to expand...

I have ordered a couple of 1mm left-hand drill bits and am hoping to back it out with those. Finding EZ-Outs for M1.6 screws is not easy.

Dan Daniel said:

You might need to go to wider diameter bits. Although this isn't 'best practice,' screw threads do have a little excess material and will work fine in most case if your drill bit reduces them slightly. And you don't need absolutely perfect threads at all points in all directions.

Click to expand...

Worst case it to drill out to 2mm and retap, but I'm hoping to keep it as original as possible, because....

Dan Daniel said:

(oh geez, did I just way that to a Hasselblad guy?? my apologies. yes your camera is amazing!!!

Click to expand...

At last, someone who understands!

It's not a high load or high vibration joint. I have wondered how important that screw really is, but Hasselblad put one there, so best that one stays there.

Thanks for your suggestions - it gives me hope.

4season said:

I've had some success with removing screws as small as ~1 mm with screw extractors, similar to types used for wristwatch repair. But if it's fused into place due to corrosion, you might wind up having the drill it out as best you can. The steel used for these tools is hard and fairly brittle, but I can generally get a few uses out of them before they become toothless. I chuck these into a pin vise.

Older Hasselblad backs have a plastic bumper which serves as the counter's zero-stop, but over time, the tip can break off, resulting in the counter resetting to some random, unhelpful position. Replacements can be home-made. I've had success using polyethylene scrap from a milk or juice container.

View attachment 406165

Click to expand...

Thanks for the link. I spent last night trying to find extractors for m1.6 screws. If a 1mm left-hand bit doesn't work (easier to source) these should do the job if I gan get them to grip.

I had a play with the gearing and got the counter to reset. While waiting for a drill bit to arrive I'll service the gears, reassemble, and test.

I'm hoping that I can resurrect the back - there a few enough of these older ones working now.

Sirius Glass said:

Problem 1: drill a small diameter pilot hole and use an easy out to remove the screw. An easy out is a conical left hand threaded tool designed for exactly this type of problem.

Click to expand...

Thanks Sirius. Easy-out brand doesn't go quite that small - not that I could find. I'll try a 1mm left-hand drill bit first.