Rolleicord V Viewfinder screws - what size?

[runswithsizzers]

I just ordered a Rick Oleson screen for my Rolleicord V. I've already had the viewfinder off to clean the mirror -- easy enough, just four small screws. I didn't have any problems, but I'm afraid I'm going to loose one of those little screws. (Someone has already lost one and replaced it with a different style head.)

Does anyone know for sure what size these four viewfinder screws are?

While I had it apart, I tried to measure one of the original 3 screws. Measuring across the tops of the threads, I think the outside diameter is about 2.7-2.8mm. And using a metric screw pitch gauge, the thread spacing looks like about 0.5mm. But the screws are short, only 4mm, so it's hard to really see what's going on with the pitch.

Looking at charts of standard metric screws, it seems like my measured diameter is a little bit too large for a M2.5-0.45 and a little bit too small for a M3-0.50.

When I was in the bicycle business (decades ago), I used to be confident measuring down to about 0.2mm. But my old Eldi vernier calipers may be worn, and I know my eyesight is not as good as it used to be, so maybe I just can't measure anymore? Or is it possible Rollei used something other than a standard metric size?

 

[Dan Daniel]

I get ~1.65 x 0.50 mm. I see that ~1.65 a lot. I assume that's a nominal 1.7

I don't know enough about small machine screws, assorted thread standards, etc. to say if this is typical for metric threads. Rollei used assorted diameters and threading for similar purposes. Often an assembly seems to have varied diameters and threading simply to make it so that only one type of screw would work in one type of place. Considering how many camera they were making I expect they could get whatever they want made up.

If all you need is a replacement screw, drop me a DM with your address and I can send you one or two.

 

[runswithsizzers]

@Dan Daniel, Thanks for your reply. But we must be measuring different screws? I could easily be off by a few tenths of a millimeter, but surely not by a whole millimeter!

 

[BMbikerider]

The back of my laptop is held in place by a number of small screws some as short as 2mm and others about 7mm. After removing the back to replace a cooling fan replacing a cooling fan I was short of 3 so I went to a computer repairers (NOT Curry's) and asked if they had anything similar. The owner had quick look in a box of odds and ends and produced what I needed. Nor did he want paying!

The thread of the screw may be the main problem, but at least they should be metric which is a good start If they don't have any at least they should be able to accurately state the size and thread pitch.

Failing that how about a camera repairer.

What have you got to loose?

 

[Ian C]

Screws are generally slightly smaller in diameter than the nominal size to provide assembly clearance. The diameters also vary from one maker to another and can vary slightly from one production run to another depending on the dies and their condition (new or worn through use) used to form the screws.

They are generally formed from annealed metal (relatively soft for easy forming). Then they are heat treated for strength and hardness and then tempered to remove brittleness (that would make them prone to breakage) leaving them tough and strong. These heat treatments can shrink the diameter somewhat, but doesn’t interfere with their function.

Here are some small metric screw dimensions in the following link.

https://www.accu.co.uk/p/117-iso-metric-thread-dimensions

Note that M1.7 is not shown. Mamiya cameras use M1.7 x 0.35 mm screws for at least some parts. This size is often omitted from metric screw dimension tables.

Here is an example.

https://www.mcmaster.com/products/screws/thread-size~m1-7/

Of course, your screw measures 2.8 mm diameter. So, the screw might be a nominal M3. If so, the pitch is most likely 0.50 mm.

Here is a tolerance table for metric screws. It shows limits of 2.98 mm – 2.87 mm for an M3 screw.

https://fullerfasteners.com/tech/thread-tolerances-for-screws-and-nuts/

A safe and easy way to test this is to buy an M3 x 0.5 mm screw at your local hardware and test it in the thread. If it fits properly, then you know you’ve identified the nominal size and pitch. My local hardware store carries M3 x 0.5 screws. You should be able to find one without difficulty.

 

[runswithsizzers]

@Ian C, thanks for your reply. Yes, I have spent quite a bit of time looking at charts like the ones shown on the links you provided. And those specifications are the source of my concern.

As you say, a M3 screw should have a major diameter in the range of 2.98-2.87mm. And according to the same chart, an M2.5 screw should be in the range of 2.48-2.38mm. Yet my measurement of my screw is about 2.7-2.8mm -- falling into neither range. The charts for metric screws I have seen do not show anything in between M2.5 and M3.

So either my measurement is off by at least 0.07mm (quite possible), or Rollei is using something other than a standard metric screw size. If accurate, my measurements are a better fit to the specifications of an American machine screw size #4-48, but I assume it would be unlikely for Rollei to use such a screw. (#4 od = 0.1120 inch = 2.84mm); 48 tpi = metric pitch of 0.53mm)

But you are so right to suggest it is time to get empirical, and see what actually fits. Presently, 5 inches of fresh snow is keeping my MINI Cooper off the roads, but when the snow melts a little, I will go see what kind of metric screws are stocked at my local hardware store. Thanks again!

 

[Kodachromeguy]

Another (unlikely?) option: could they be Whitworth threading? After all, the Leitz LTM is 39mm × 26 turns per inch.

 

[Pieter12]

You might try contacting a technician who services Rolleiflex TLRs. Like Harry Fleenor, Dave Feely, Jimmy Koh.

 

[Laurent]

@Ian C, thanks for your reply. Yes, I have spent quite a bit of time looking at charts like the ones shown on the links you provided. And those specifications are the source of my concern.

As you say, a M3 screw should have a major diameter in the range of 2.98-2.87mm. And according to the same chart, an M2.5 screw should be in the range of 2.48-2.38mm. Yet my measurement of my screw is about 2.7-2.8mm -- falling into neither range. The charts for metric screws I have seen do not show anything in between M2.5 and M3.

So either my measurement is off by at least 0.07mm (quite possible), or Rollei is using something other than a standard metric screw size. If accurate, my measurements are a better fit to the specifications of an American machine screw size #4-48, but I assume it would be unlikely for Rollei to use such a screw. (#4 od = 0.1120 inch = 2.84mm); 48 tpi = metric pitch of 0.53mm)

But you are so right to suggest it is time to get empirical, and see what actually fits. Presently, 5 inches of fresh snow is keeping my MINI Cooper off the roads, but when the snow melts a little, I will go see what kind of metric screws are stocked at my local hardware store. Thanks again!

I would second @Ian C suggestion for M3, as the pitch of 0.5 is spot on, and diameter very close to nominals for M3. Good luck in your search.

 

[Andreas Thaler]

Screws are generally slightly smaller in diameter than the nominal size to provide assembly clearance. The diameters also vary from one maker to another and can vary slightly from one production run to another depending on the dies used to form the screws.

They are generally formed from annealed metal (relatively soft for easy forming). Then they are heat treated for strength and hardness and then tempered to remove brittleness (l that would make them prone to breakage) leaving them tough, strong. These heat treatments can shrink the diameter somewhat, but doesn’t interfere with their function.

Here are some small metric screw dimensions in the following link.

https://www.accu.co.uk/p/117-iso-metric-thread-dimensions

Note that M1.7 is not shown. Mamiya cameras use M1.7 x 0.35 mm screws for at least some parts. This size is often omitted from metric screw dimension tables.

Here is an example.

https://www.mcmaster.com/products/screws/thread-size~m1-7/

Of course, your screw measures 2.8 mm diameter. So, the screw might be a nominal M3. If so, the pitch is most likely 0.50 mm.

Here is a tolerance table for metric screws. It shows limits of 2.98 mm – 2.87 mm for an M3 screw.

https://fullerfasteners.com/tech/thread-tolerances-for-screws-and-nuts/

A safe and easy way to test this is to buy an M3 x 0.5 mm screw at your local hardware and test it in the thread. If it fits properly, then you know you’ve identified the Momina size and pitch. My local hardware store carries M3 x 0.5 screws. You should be able to find one without difficulty.

Valuable information, thank you!

 

[Ian C]

Here is video showing the making of machine screws. Some grades might not require heat treating. It omits showing the subsequent heat-treating and tempering required of high-strength screws. Those that require great strength, must be heat treated and tempered.

 

[BrianShaw]

With 5 inches of snow and a MINI, another option might be worth considering… Amazon. They have lots of small screws and screw assortments at very reasonable prices. The selection tends to emphasize hex head but there are Phillips head available. Shipping cost is always a pain to pay but sometimes one needs to do what one needs to do.

What head style do you need?

Also, if one is a replacement, verify that it is the exact same size/pitch and remember which hole it comes out of just in case it may have altered the hole threads.

 

[runswithsizzers]

As I was laying awake in the middle of the night, I suddenly realized, "If that screw is 4mm long, there is no way it is 2.75mm in diameter! The proportions of width-to-length would be all wrong!"

So, my apologies to everyone, but especially to @Dan Daniel, who was quite right when he posted, "I get ~1.65 x 0.50 mm. I see that ~1.65 a lot. I assume that's a nominal 1.7." Lesson learned, when an expert speaks, pay attention!

For no good reason, I mistakenly wrote down my measurement as "2.7-2.8mm" -- but when I measured again today, my old Eldi Swiss-made vernier calipers clearly show, 1.7-1.75mm.

I was able to double check using another caliper. This one is not Swiss (Chinese), but it is new and has a dial which I read as 0.064-0.065 inch. When converted to metric that is, 1.63-1.65mm.

Looking at the last link provided by @Ian C, the major diameter of a M1.8 screw should measure within the range of 1.697-1.781mm. My Eldi measurement fits the range for M1.8, But my Chinese calipers suggest M1.7 (range: 1.596-1.681mm). A man who has two watches never knows the time.

But whether M1.7 or M1.8, most websites show the thread pitch for those sizes as either 0.2mm or 0.35mm. True, my thread pitch gauge is a cheap one, but I am pretty sure the pitch of my Rollei viewfinder screw is a lot closer to 0.50mm than it is to 0.35. And Dan Daniel says he measured 0.50mm, as well.

So far, I have not been able to find any online source who lists either M1.7 or M1.8 screws with a thread pitch of 0.50mm.

 

[Mamiya_Repair]

Yes, Dan Daniel has given the correct size, 1.7mm-0.50mm for the hood attaching screws, this is from my repair notes on the Rolleicord V. The 0.35mm spacing is much more common on this size screw that is why you are having a hard time finding the 0.50mm size which is a coarse thread. Unfortunately I don't have a source for the correct size as the usual suspects only seem to carry 0.35mm.

 

[Motopreserve]

I’ve done my share of searching for odd-ball metric here in the US, for rebuilding vintage motorcycles. It can be a serious drag.

I don’t own a Rollei, so I’m not sure what type of head you require. But this place has a decent assortment of metric screws in small sizes, at various pitch.

Metric Machine Screws