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The rail for Mamiya 645 Auto Bellows
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PostPosted: Sat Mar 11, 2023 7:31 pm    Post subject: The rail for Mamiya 645 Auto Bellows Reply with quote

I was not sure which forum section my question woud fit the best. So I am putting it in DIY, as the previous post here was just targetting the bellows topic.

I've got a perfectly crafted Mamiya 645 Auto Bellows which is well preserved but lacks the rail. The nice price was a good justification, even though as is the bellows could not work. I hoped the rail taken from Soligor Multiflex Autobellows (for 135mm cameras) could be a solution, but it does not fit.

So, need either to buy a spare rail (where, for which amount?) or to 3D print or to command it from a lathe expert. What is your experience with such issues, taking into account that MF bellows cost times higher than SF ones?

Maybe I should start from providing myself with precise measures, in order to search for an eventual substitute or to command one. Could someone of you, fellows, measure your M645 rail and tell the measures?



I thank you in advance.


PostPosted: Sat Mar 11, 2023 7:41 pm    Post subject: Reply with quote

A lot of these OEM bellows parts were supplied by third party manufacturers such as Novoflex, Unitor, etc. (e.g. the rails, actual bellows etc.)

There is a good chance that e.g. the rails of the Bronica bellows system for the ETR and SQ series will be good fit, if you can find a cheap broken one that is.


PostPosted: Sat Mar 11, 2023 7:58 pm    Post subject: Reply with quote

Thank you very much for your hint. I think I still need of some crucial measures, to be sure I am hunting for the correct spare part.

Maybe the fellows who experimented with the MF bellows in the previous thread could give the measures.


PostPosted: Sun Mar 12, 2023 3:32 pm    Post subject: Reply with quote

I took some measures of the internal dimensions of the bellows which are put on the rail and measured the rail of Soligor Multiflex Auto Bellows whose rail does not fit well Mamiya bellows, but has some similar parameters.

Here are the results. I'd really appreciate if those having Mamiya 645 bellows could confirm or correct them:

36mm - the rail slot width in its largest upper part, so the rail upper width must be 35mm (?), with rounded corners.
28mm - the rail slot narrower bottom part, so the rail must bebe 27.5mm (?).
200mm - the rail length (measured on Soligor auto bellows).
8.8mm - the rail slot depth, so the rail height must be 8.5mm (measured on Soligor auto bellows).
1.6mm - the ruling wheel upstands from the bellows mechanism surface.
7mm - the width of the guiding dented inlay in the rail (measured on Soligor auto bellows).
1mm (?) - the step of the ruling dented inlay in the rail grasped by the small dented wheel in the bellows (measured on Soligor auto bellows).
1mm - step down difference from the rail upper surface to the ruling dented insert in the rail (measured on Soligor auto bellows).
3mm - the total height of the ruling dented inlay in the rail (measured on Soligor auto bellows).
3mm - the height square bottom part of the rail (located below the trapezoid ruling part) (measured on Soligor auto bellows).


PostPosted: Sun Mar 12, 2023 4:42 pm    Post subject: Reply with quote

Those measurements are very close (i.e. I suspect identical) to the ones of my Bronica Auto bellows S rail, as well as those of my Minolta Bellows IV and Auto Bellows III.

The rails of my Minolta bellows (Auto bellows III, Bellows IV) look identical to the rails I saw in online images of the Mamiya 645 bellows, and they also have the same measurements as you mentioned.

The images I saw of the Soligor Multiflex Bellows suggest the Soligor rail has a metal rack (the thin toothed rail inlay), whereas the images I have seen of the Mamiya 645 bellows have a plastic (likely nylon) rack. Both the Bronica as well as the Minolta Bellows IV and Auto Bellows III have plastic racks. Otherwise the Soligor rail again looks the same, so maybe the issue is one of a metal vs a plastic rack?

In any case, used Minolta Bellows IV are not expensive, especially if the bellows itself is faulty, so may be worth a try. Sometimes you can find the Minolta bellows rail by itself.

The Contax bellows rails also look the same; as I said earlier, all these rails appear to come from the same (3rd party?) manufacturer, with only minor cosmetic differences, or a difference in the rack used (metal vs. nylon).

EDIT: re. the Soligor rails not fitting well; the clamps used in the bellows stands usually have four tiny slotted set-screws (two either side), by which the play/clamping friction can be adjusted; maybe they are set a bit tight on your bellows?


PostPosted: Sun Mar 12, 2023 6:15 pm    Post subject: Reply with quote

Thank you, Mark, for insisting on the idea of Soligor bellows! When I tried its rail first, I did not manage to put M645 bellows on and concluded a small but significant difference in dimensions. After your fresh comment I tried again, starting from the other side of M645 bellows, and it worked!

It took me more effort to put the second stand (with the tightening clamp relaxed, so I wonder the reason). But it worked anyway. Now I may try using both, separately for sure, on the same rail.



The full metal Soligor rail gives an additional weight to the whole construction which is not really welcome if taken outside. I wonder if a 3D printed plastic rail could be strudy enough for the purpose. Anyway, I have a good point to start with.


PostPosted: Sun Mar 12, 2023 7:36 pm    Post subject: Reply with quote

alex ph wrote:
Thank you, Mark, for insisting on the idea of Soligor bellows! When I tried its rail first, I did not manage to put M645 bellows on and concluded a small but significant difference in dimensions. After your fresh comment I tried again, starting from the other side of M645 bellows, and it worked!

It took me more effort to put the second stand (with the tightening clamp relaxed, so I wonder the reason). But it worked anyway. Now I may try using both, separately for sure, on the same rail.

The full metal Soligor rail gives an additional weight to the whole construction which is not really welcome if taken outside. I wonder if a 3D printed plastic rail could be strudy enough for the purpose. Anyway, I have a good point to start with.


Like 1

I doubt whether a plastic rail would be stiff enough, unless it were made using a glass filled polymer:

https://en.wikipedia.org/wiki/Glass-filled_polymer

Most quality plastic parts used in camera bodies and lenses are made using injection-moulded glass-filled polymers; glass-filled polycarbonate predominantly.

This should not be confused with resin bonded glass-fibre matting by the way, such as used in the hulls of boats etc.; that's something entirely different Wink


PostPosted: Sun Mar 12, 2023 7:43 pm    Post subject: Reply with quote

Happy Dog

Are glass-filled polycarbonates used in 3D printing? If yes, this could be an idea for the future.

For the moment, I looked through 3D printing services to discover that even a simple ABS M42 to Sony E adapter would cost, commanded individually, at least 15 euros Shocked. While you may get a metal one cheaper from China, and already finished (while you often need to file and polish 3D printed ones). Printing a rail with 100% filling might cost way more.


PostPosted: Sun Mar 12, 2023 8:33 pm    Post subject: Reply with quote

alex ph wrote:
Happy Dog

Are glass-filled polycarbonates used in 3D printing? If yes, this could be an idea for the future.

For the moment, I looked through 3D printing services to discover that even a simple ABS M42 to Sony E adapter would cost, commanded individually, at least 15 euros Shocked. While you may get a metal one cheaper from China, and already finished (while you often need to file and polish 3D printed ones). Printing a rail with 100% filling might cost way more.


Glass filled nylon for 3D printing is available. Filling is usually around the 30% level though, not 100% Wink
You often see it on the inside of an injection moulding, a type marking such as eg. "PA 66 GF30", which is polyamide 66 (a type of Nylon) with 30% glass fibre fill.


PostPosted: Sun Mar 12, 2023 9:45 pm    Post subject: Reply with quote

Good to know!

I must have misunderstood the concept of filling. I thought it deals with small cavities in the finished item. So if you make a rail with 30% filling, it would be lighter but also less strudy than a 100% one. This does not work like that?


PostPosted: Mon Mar 13, 2023 2:22 pm    Post subject: Reply with quote

alex ph wrote:
Good to know!

I must have misunderstood the concept of filling. I thought it deals with small cavities in the finished item. So if you make a rail with 30% filling, it would be lighter but also less strudy than a 100% one. This does not work like that?


No, glass filled polymer is a polymer (plastic) that has a certain amount of either powdered glass or very thin short (1-3mm long) glass fibres mixed in throughout. This is then molten and injection-moulded. The finished product is then mostly the polymer with an enormous number of thin short glass fibre strands randomly distributed within the polymer bulk. This gives it extra rigidity, strength, and surface hardness.

As I said, on the inside of the injection moulded part you can often see a polymer type marking with e.g. a "GF30" suffix that indicates a 30% glass fibre fill ratio.

You can also learn to recognise these plastics by their exterior appearance, and when you score the plastic with the tip of a sharp knife you can hear the different sound of the knife going over the glass particles or fibres as compared to a plastic that doesn't contain the glass filler.

Most plastic camera parts where dimensional stability matters are made with glass filled polymers; mostly glass filled polycarbonate. Glass-filled polycarbonate camera bodies are sometimes over-moulded over a metal mirror box core, e.g. the later Minolta X-series bodies.

https://www.directplastics.co.uk/news/learn-about-glass-filled-engineering-plastics

https://www.youtube.com/watch?v=8RkJHksEH54

https://www.youtube.com/watch?v=4YHe1csv2ag


PostPosted: Mon Mar 13, 2023 3:28 pm    Post subject: Reply with quote

Thank you for your precise explanation! The 30% filling with tiny glass sticks makes perfect sense.

I mixed it with the 3D printing parameter which varies from 30% to 100% of the material usage while printing. The higher the filling rate, the bolder the item is -> more plastic is used -> higher the price you pay.

The videos you provided is a nice introduction into the varierty fiber-glass applications. Like 1 small