Watchmaking: Machining a 0.6 mm Screw [video]
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Screw making was automated by 1871. Here's an early automatic screw machine.[1] The video says 60,000 screws a day, but that must have been the whole shop, not one machine. You can see that the cycle time is about 10 seconds per screw. Who needs computers? We program with cams! Complex cam-programmed industrial machines were what made manufactured parts cheap.
Here's synchronized thread rolling using a CNC lathe.[2] That's a more modern one-off approach. Thread rolling squeezes the threads into the screw, rather than cutting out metal. Rolled small screws are stronger than cut screws. Needs a specialized tool.
That's not the full speed modern production process. This is.[3] A relatively simple machine turns out small screws at about one every 250ms. Over 100,000 screws per shift. This screw rolling machine can go down to 0.6mm, so it can do the job in the original video.
Here's a larger, slower, bolt rolling machine, so you can see the process.[4] It's very simple. A round piece of metal is rolled between two file-grooved die plates, and the threads are pushed into the metal.
This is why screws are cheap.
[1] https://www.youtube.com/watch?v=YCmnUP5gx78
[2] https://www.youtube.com/watch?v=-eWghSLN3ng
Also a dumb question, is there a way to identify the exact size of a driver that was meant to turn a particular screw? For example, you can use various sizes of Philips to turn a philips screw. Some might be slightly too small and others might be slightly too big and while the screw turns it may be damaging the screw even though it is not apparently visible at the moment. This also goes back to my original question about quality. I find a lot of screws seem to be really soft metal. Is this a quality issue or is that by design? Wish there was some central resource I could learn all about screws from instead of having to scrounge random forums.
A typical screw or bolt needs three to five threads to reach maximum strength, if you just screw a screw into a plate or sheet of wood for three to five threads you should be able to torque it down to under it's sheer strength (which for almost all fastener dimensions and materials is specified). If it breaks then you can consider the whole batch faulty.
The easiest way to ensure that you get good quality is to go for the premium brands of fasteners, it won't be cheap but at least your stuff won't fall apart when you need it most. Avoid retail outlets, buy where the professionals buy.
For your question about screwdriver fit, unfortunately that ends up being a judgement call. Be forewarned that for 'phillips' there are identical looking JIS screws [0], it takes a bit of experience to identify what driver to use. Some basic guidelines are, to use the biggest driver that will still bottom out at the tip in the screw, and if the product is of Japanese origin to use JIS drivers. It's very hard to measure, but with experience it isn't hard to tell what but a screw uses. Fit a good quality driver into the screw, and visually check if the flutes of the driver engage all the way to the end of the screen's flutes. Note that you need to use a good screwdriver here, I've seen the cheap screwdrivers ground at 15 degrees off of the correct angle.
And if you want all the specs on a particular screw, picking up an older copy of Machinery's Handbook will give you more detail than you were aware existed.
Although from your question, it seems like you are working with poor quality screwdrivers. Cheap screwdrivers make any screw feel like garbage and strip out stuff, it's worth it to invest in good ones. Surprisingly, harbor freight [1] has a set that I own and I would recommend over my Wera drivers, they are not bad at all. If you want to buy once and be done, Snap-On makes by far the best set [2],although keep on mind that $200 price tag will also need to be supplemented with another $50 Phillips #3 driver.
Or, if you don't need to access screws down deep wells of plastic and can use them, the Bosch replacement bits for impact drivers commonly available at hardware stores are fairly decent, although they aren't as good as the Harbor Freight Icon set linked as the cheaper option. This is one thing where quality costs, and you need to determine if you want/need that quality. But if every screw is feeling soft and stripping, it is almost certainly your drivers.
[0] https://www.amazon.com/Hozan-JIS-4-JIS-Screwdriver-3rd/dp/B0... (I don't have experience with this particular set, I have a Vessel set that is OK but not good}
[1] https://www.harborfreight.com/professional-mechanics-screwdr...
[2] https://shop.snapon.com/product/Instinct-Soft-Handle/8-pc-In...
> I have no way of gauging the overall quality of screws
For machine screws/bolts, grade should be stamped on the bolt, https://www.aftfasteners.com/grades-of-bolts-bolt-grade-mark...
Monster Bolts in Florida sells small quantities of quality screws/bolts, with accurate metal-grade metadata and fair prices, https://monsterbolts.com
> Is there a way to identify the exact size of a driver that was meant to turn a particular screw?
PicQuic in Canada sells handles with an extensive range of 1/4" driver bits that also work in power tools, see eBay and http://picquic.ca/bits-and-accessories/
> Wish there was some central resource I could learn all about screws from instead of having to scrounge random forums
And the importance of that is hard to overstate. Originally fasteners were the product of blacksmiths, and blacksmiths tended to be the best paid people in a village after the bankers. It wasn't rare to see 'hardware' (nails, screws and other useful bits of metal) be painstakingly recovered and recycled and you could find items such as nails and screws in inheritances because of their value.
Without modern cheap fasteners our society would quite literally fall apart.
We are completely spoiled by modern materials science, I'm typing this out resting my elbow on a workbench that would have been worth a literal kings ransom 500 years ago, and now having a 4x8' bench of 5/16" plate steel isn't an insane thing to own. 500 years ago, this bench would equal the yearly iron output of a normal European country, with a price tag to boot. And automated manufacture of fasteners makes the modern world run, even with a lathe making a single screw takes me at least 5 minutes assuming everything is already set up. Forging a nail? Here [2] is a modern blacksmith taking ~2 minutes and 3 heats to forge a simple nail. Having exposure to blacksmithing, I'm always shocked at how cheap modern fasteners are.
[0]https://acoup.blog/tag/iron/ [1]https://kingdom-come-deliverance.fandom.com/wiki/Unexpected_... [2]https://m.youtube.com/watch?v=ZBfkmPt-WYw
Most of his work involves horses, which brings in good money but is a real risk for your back.
Farrier work is still needed, since factories can't stamp out horseshoes that exactly fit the horse's foot, so a blacksmith needs to custom match the shoe to the hoof.
I'm curious why you say it is a risk to your back? Farriers can definitely get injured, I know a few who have had broken ribs, but I've never heard of that having back issues. Is there a risk I'm not aware of?
Yes, as I wrote, my cousin is one of them.
When shoeing a horse you carry a good chunk of the weight of the horse, and that's before we get into the kind of contortions you have to go through to do a proper job mostly under a horse.
Pretty pleased with what o made: https://youtube.com/shorts/Ly4k-55902c?feature=share
Was this done in coal?
It was exhausting - towards the end I could barely lift the hammer.
I did it here - https://www.hotmetalworks.co.uk/
The museum it’s in is worth a visit as well - especially when they are running all the steam engines.
They offer a 4-year Bachelor of Arts degree with concentrations in blacksmithing, carpentry/timber framing, plastering, stone carving, and classical architecture. Many of them go on to start their own firms after graduation and gaining work experience.
If you want to learn more about blacksmithing, I would point you at the Artisan Blacksmith Association of North America at ABANA.org.
https://www.youtube.com/watch?v=H6Dnmd3lDzA&list=PLY67-4BrEa... << this is the lathe one
https://www.youtube.com/watch?v=FyuG-B95PQs&list=PLY67-4BrEa... is the one for the small vertical mill.
One question - why did watchmaking industry started/thrived in those rather remote places up in the mountains? I get that not everybody wanted/could be in Geneva, but remoteness helps little when doing business, apart from driving costs down. You need very specifically skilled people to get to those remote places. Some small village(s) say near Yverdon les Bains would make more sense to me, in the past and now too. On the way back saw new big glass&concrete building of Vacheron Constantin literally in the middle of nowhere, in between 2 forests and small road.
https://medium.com/watchmakers-ch/the-history-of-the-swiss-w...
I've really been interested in getting a jewelers lathe with a goal of making smaller parts and particularly screws. but it looks very expensive and intimidating. many thousands of dollars for a few pounds of 100 year old steel with a lot of very fussy and foreign looking tooling. I really love to fix things up and learn, but would love some advice about how to start.
anyone have a suggestion?
I know a fairly large number of hobby machinists and some of them are quite advanced in age. They still turn out quality work, doing stuff that they love. But you can tell that in some of these cases the writing is on the wall and they'll stretch it as long as they can.
Sherline lathes are very small, and I think its what clickspring runs.
Obviously 'big iron' is better. But even if you've got the space, you've got to choose between high prices and the risk and project of going second hand.
If you have the space and the budget, you probably want a TRAK toolroom lathe - they have a CNC controller with a simple conversational interface, but they're designed to be used as a mostly-manual lathe with canned cycles. Excellent machines from a supplier that really understands the needs of toolroom and job shop machinists.
If that's too big and/or too costly, you probably want a rebuilt Hardinge HLV-H. Yes, they are 50+ years old, but they're basically the perfect small lathe and they can still hold very tight tolerances if they're properly cared for. The HLV-H is still being cloned by a number of the higher-end Taiwanese manufacturers, for very good reason.
Failing that, try Precision Matthews. They sell basically the same import stuff as everyone else, but they have very good QC and aftersales support. Something like the PM-1236 is a massive step up in rigidity and quality compared to the <$2000 Chinese machines. Not perfect, but by far the best value if you want to buy a new machine.
That said, I've found that it's fine to turn down the stock on the lathe but using tiny dies, <1mm, on the machine is a pain (I have to relearn the 'feel' every time).
My solution is to clamp the die and use a pin chuck and do the operation by hand. This way, I've some tactile feedback and I don't wreck either the die or the work as often.
Of course, that's no solution if one needs hundreds of them.
Moreover, trying to figure out what the threads are is often pot luck (thread gauges down there are nigh on nonexistent-in my world anyway—and you need a microscope or thread viewing metrology stuff which I don't have). British instruments before, say, 40 years ago usually used BA (British Association), US—UNF and European and Japanese—ISO metric, but then there's also the pre-ISO metric to contend with on old stuff.
Surprisingly, when they're that small it often doesn't matter. Guesstimates combined with brute force and ignorance usually got the job done.
It's fair to say I'd rarely tackle anything below 0.8mm although I once filed a smaller one by hand. Fortunately, most of the time I scavenge screws from old instruments, clocks, watches and laptop PCs (these however are larger, usually between 1 and 3mm). I never throw away old stuff without disassembling it for the screws.
Nowadays, it's not a problem because it's easy to get packs of just about any size screws one wants, it wasn't so 40 or so years ago. Incidentally, my grandfather was a watchmaker and jeweler and my father a mechanical engineer so I saw watchmaker's lathes at a very young age.
BTW, my fulltime profession is moving electrons about (or trying to). They're somewhat smaller than those tiny screws so I can only guess where they are by proxy. ;-)
PS: I've just noticed an apostrophe typo in my post— 's instead of s', which I now can't correct. You see, one has to be an annoying persnickety bastard to muck around with this stuff.
https://community.carbide3d.com/t/watchmaking-on-the-nomad/4...
https://spectrum.ieee.org/ibm-goes-for-world-record-in-noise...
“Foundations of Mechanical Accuracy” Wayne R. Moore – 1970
Highly recommended.
It really is. I have some small experience with the industry, an acquaintance I didn't expect to have. The engineering that goes into metrology-grade measurement is incredible.