The whole vexed question of lens screws

[Tom Caldwell]

I mean the little ones that get broken and lost, the FSU lenses in particular.

I have no real idea of how screws are actually made but I imagine modern screw production is carried out by automated machinery which in some way hreads what is basically wire then stamps a suitable head on it and cuts it automaticaly to size.

I have speculated that perhaps the screws of the early industry might even have been made on the bench using small machines and/or jigs - also from a base wire stock. With largely aluminium based body stock brass wire might have been hard enough an this is confirmed to a point by the readiness to break lugs and general rough manufactured look. I have noted though that most small screws are subject to magetic attraction in which case a brass source stock is ruled out.

I simply do not know and am guessing whilst asking for input from those better informed.

I have romanced about small individual bench jigs, but this is only romance and it would be interesting to hear from someone who actually knows just how these small screws were physically made. For small batches of on-demand production these jigs (if they ever existed) could have a steady demand from lens repair amateurs such as myself, or replicas of them could be made from working designs.

Being able to make my own in a small scale on demand would be wonderful.

A matchbox full of these screws would keep a whole lot of amateur repairers happy for quite some time. Although literally millions of lenses were made in the FSU which is testified by the pricing of and numbers still available today the old unused screw stocks if they ever existed as such would have been recycled as scrap metal long ago. My fertile imagination sees the entire industry stock of left over screws in the bottom of a single single dumpster heading for the metal refinery.

Somewhere there might even be a hidden cache of screws now worth much more than their weight in gold.

--
Tom Caldwell

 

[mapgraphs]

I mean the little ones that get broken and lost, the FSU lenses in particular.

...

Somewhere there might even be a hidden cache of screws now worth much more than their weight in gold.

 

[Trad59]

I've not delved into the Russian lineup, but have opened up a few Contax lenses and found the screws in there to be pretty well made. Old camera bodies that go for a dime are obviously a pretty good source of screws, generally hundreds of them in a body, so one or more of them are bound to fit your needs. Don't know where that dumpster might be, but spectacle and watch screws are also in the ballpark re diameter/pitch/thread form. You can buy batches (generally a box of 1000 !) of fine /micro screws on eBay, these again are mostly for specs or watches. Just think of what you could do with a a thousand screws...it's kind of like buying a box of hundreds of screws for around the home, when all you need is that one...

back to part of your question, this short article provides a concise overview of fine screw manufacture

How screw is made - material, manufacture, making, history, used, parts, procedure, machine, History

What I keep my eyes out for are the aperture balls and springs...

 

[Trad59]

Might be preaching to the converted, and perhaps even less relevant to FSU lenses, but one of best purchases I made was in a couple of JIS (Japanese Industry Standard) screwdrivers, they're available online; vessel, moody and cool tools and others supply these. They come in very fine tips, 1, 0, 00 and 000.

Eg in Contax, and I assume Nikon, possibly Pentax lenses a quality JIS screwdriver is possibly going to save having to replace a chewed up screw because it's head has been mangled. JIS screws look much like a Phillips (some call this the cross head) screw, JIS always fit Phillip fasteners, but JIS screws will/may be damaged by a Phillips screwdriver if it is tight. JIS screw heads are sometimes identifiable by a single raised dot to one side of the cross slot.

 

[Tom Caldwell]

Firstly, I have trawled the internet - the hardware store and wholesaler's packets of screws are not overly helpful, nor are those from watchmakers and reading glass screws are more specialised and even more limited for camera use. The act is that in lenses almost every screw is different and quite often specialised and not interchangeable. There are not "hundreds" of screws in any lens but maybe twenty a most - a good few of these are either holding the body or end on to the lens structure. Others are stop screws or other screws with special shapes. Even with the same manufacturer I doubt if more than a few screw types are interchangeable between lenses.

A packet of assorted hobby micro screws will more than likely turn up 1% of that which might be useful in a lens.

I am not an expert lens repairer but I am well past the beginner stage and have worked on quite a few lenses in the last five years or so.

Therefore I am not looking for generalised place where to look for small screws in a sort of "lucky dip" but for specific screws that can be used on lenses - preferably old FSU lenses which are the ones that break.

Furthermore I was very interested in finding out how screws are made in general but even more interested in how the screws for 40-60 year old FSU lenses were made and on whether the machinery was large scale and/or whether if the screws were made on basic equipment if such equipment was known and if so what did it look like and is it a commercial proposition to acquire or build something similar. ie: specific usable information.

Few FSU screws, if any have other than slot heads. I use high quality screwdrivers but most of my "screw problems" have been created by others before me. The screws shown below are in relatively good condition. the one on the left shows its intact slot. Both show signs of some corrosion which made their removal somewhat difficult. They are a standard pointed end grub screw type flat slot driven. As grub screws are common it may be possible to obtain tiny allen key head versions. However it might be beyond an allen key ability to make.

What size they actually are is difficult to ascertain as the regular match head comparison signifies. Such tiny size makes them difficult to recognise as a screw with old eyes and I can only see them well enough to fit on to my smallest size screwdriver using a magnified head band.

Measuring even with vernier calipers is well nigh impossible.


Jupiter-8 aperture fixing grub screws with match head to show relative size - sorry for the fuzzy focus.

Four thread turns only before the slot.

I thought they would be too small to measure but I did get the verniers on one. Larger than they look - 1.2mm diameter and 1.5mm head to point.

--
Tom Caldwell

 

[Trad59]

Understood. Verniers and screw pitch gauges don't cut it with stuff this small. Perfect job if you have access to a metrology lab - optical microscopes, and or an optical projection comparator.

 

[Tom Caldwell]

Understood. Verniers and screw pitch gauges don't cut it with stuff this small. Perfect job if you have access to a metrology lab - optical microscopes, and or an optical projection comparator.

Yes well I hope I got it right, tweezers and a headband magnifier ... at least the headband made it easier to read the verniers - screw pitch? I thought it was pretty good just getting it between the vernier blades. It certainly looks smaller than the verniers told me, but I looked and I looked and it seemed to be sitting there clamped up correctly. Looks can be deceiving though.

 

[mirthseeker]

A micrometer is going to give you a far more accurate measurement of your grub screws.

A google search for "micro set screw" brought up this manufacturer , they offer free samples of flat slot micro set screws ;-).

Or try this company.

 

[Tom Caldwell]

A micrometer is going to give you a far more accurate measurement of your grub screws.

A google search for "micro set screw" brought up this manufacturer , they offer free samples of flat slot micro set screws ;-).

Thanks for your practical help, I have already found this company and they have advised that my sample screws are on the way. I am hoping that my measurement is correct - if not then it is going to be micrometer to the fore. If their price is reasonable I will stock up on screws that I often need.

It might be cheaper than buying "broken lenses" for parts and hoping that I can salvage a few screws from them. There is no guarantee that the salvaged screws will be useful in any case. I have decided that old lenses are not a good source of spare parts. They are usually in deep trouble anyway and it is doubtful that they will produce anything of value - then there is the price - broken lenses for parts can be almost as expensive as working ones.

My next and current project is on how to find supplies of the internal spacers that lenses use. It would be best to be able to make these on demand to size. I have one lens that came missing a spacer and others whose lack of proper focus makes me suspect that they also are missing spacers. Also from time to time I find that the lenses need spacer adjustment. This not only means spacer/shims of the correct internal/external dimension but also in various thicknesses.

So is it possible to regularise the size of the spacers to a few parts of varying thickness? Or is it going to be a case of punch your own from stock? Then appropriate size dies are needed. Thicker spacers might be cut from tube stock on a metal lathe provided tube of the correct dimensions can be found. But more probably the spacers are good candidates for printing on a 3D printer.

These are rhetorical "talking to myself" musings. I will work something out, but comments from others who have been down this track are welcome.

Or try this company.