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Machine or Hand Made?

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A friend brought a very old bolt and nut to me and challenged me to make one like it, because he thinks it is hand made.  I think it's machine made, therefore I didn't accept the challenge (I couldn't make one like it on my best day, anyway!)  What do you think?

 

Bolt and Nut 5.jpg

Bolt and Nut 4.jpg

Bolt and Nut 2.jpg

Bolt and Nut 1.jpg

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I would say handmade. The imperfect dome on the bolt and the tail on the square nut are what make me say so- its done by a professional, no doubt.. 

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I've made bolts and nuts before. It's not hard, but there is absolutely zero profit in it unless you are doing something quite weird.

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Machine or handmade, is probably not the right proposition. Older machine replaced the hand of the operator only in that they made things quicker, but a bolt of that nature if made by hand or by an old machine would look almost identical since both would use a jig to make the bolt and the nut and the thread was cut the same way in both cases. If you spent the time to make a jig or rather jigs, you could make the bolt and nut very easy in a few hammer strokes. 

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Sure looks like "mass produced" hardware to me.

The wooden "sweeps" on early Combines were attached with Carriage Bolts and "Knock Off" Nuts just like that.

.

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The underside of the head looked like it showed a swage line to me and so was probably made in a machine.

The other piece, ?

One problem with factory vs hand forged is that old factories may have employed hundreds of smiths hand forging stuff all day long, 6 days a week.

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Both--it doesn't have to be one or the other.  Early bolt making...and even some current bolt making...includes hand work and machine work.  For instance, the nut was probably machine cut but the tail hand refined and curled.

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1 hour ago, Kozzy said:

Both--it doesn't have to be one or the other.  Early bolt making...and even some current bolt making...includes hand work and machine work.  For instance, the nut was probably machine cut but the tail hand refined and curled.

That being said how does one tell? Sure some things appear hand forged but how does anyone know if the screw threads were cut by machine or hand done with a tap and die set?

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Threads on bolts, even long ago, were almost always rolled rather than cut.  One sign of rolled threads can be (not is) that the threaded portion looks a bit squeezed down in diameter from the shank portion.  Sometimes hard to see on something rusted.  Might be easier to comprehend if you understand the process--here's a video of an old school flat die thread rolling machine:

They use rotary rolling these days in general because it's a faster process and easier to automate.  Easy to find those videos.

On that nut, there is a 99% chance that it's been effectively hand tapped due to the odd shape, even if there was power to the tap involved.  

Old school continuous nut tappers used a special "hook tap".  The untapped nuts are fed continuously through a rotating tube to the cutting end of the tap, and ejected from the hook end of the tap.  The hook keeps the tap from spinning under the rotating force of the spinning nuts.  Can't find a video but here's a pic of one style of hook tap.  Many have a full 180 degree hook.  

tap_10-11.jpg

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Hand cut threads are made to fit each other, ie bolt and nut, and fit no other. This is why Whitworth attempted to standardise everything which was such a good idea everyone else jumped on the band wagon and unstandardised it all....!!!!! ;)

 

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Moxon mentioned in Mechanicks Exercises, pub 1703, that every blacksmith should have and use a screw plate

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19 hours ago, George Geist said:

That being said how does one tell? Sure some things appear hand forged but how does anyone know if the screw threads were cut by machine or hand done with a tap and die set?

While there are no guarantees, ... the end of the Carriage Bolt appears to be heavily chamfered.

This is indicative of a blank that was prepared to receive "cut" threads.

Because they are cut right up to the square section, I'd further speculate that, for practical reasons, this was done with a one piece "hand" die, rather than a Chaser Head.

 

On a rolled thread, the end of the bolt does not require a taper to "start" the die, and most commonly, tends to displace material at the end of the thread, resulting in a more "flattened", ( or slightly "cupped" ) bolt end.

.

 

 

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On 2017-02-09 at 11:31 PM, Kozzy said:

They use rotary rolling these days in general because it's a faster process and easier to automate.  Easy to find those videos.

 

Another good reason is that a rolled thread is stronger than a cut one

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1 hour ago, gote said:

Another good reason is that a rolled thread is stronger than a cut one

I can see how this might be the case with wrought iron (given its fibrous structure),  but is it actually true with steel?  I suppose one might make an argument that rolling work-hardens the steel, but wouldn't that effect be eliminated by any subsequent heat-treatment? 

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6 hours ago, JHCC said:

I can see how this might be the case with wrought iron (given its fibrous structure),  but is it actually true with steel?  I suppose one might make an argument that rolling work-hardens the steel, but wouldn't that effect be eliminated by any subsequent heat-treatment? 

No it would be because the rolled thread have more of a radius in the bottom while the cut thread presents a sharp notch which is a stress riser or the point at which a crack can begin also known as the notch effect.

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Rolled threads form the grain structure to the shape of the thread, whereas cutting them cuts across the grain structure.  Rolling is a cold forging process, resulting in a stronger thread. Cut threads can also have a root radius, it all depends on the tool, and the thread call out on the print. 

We did rolled threads on the CNC machines at the shop I worked at.

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On ‎2‎/‎11‎/‎2017 at 6:46 AM, JHCC said:

I can see how this might be the case with wrought iron (given its fibrous structure),  but is it actually true with steel?  I suppose one might make an argument that rolling work-hardens the steel, but wouldn't that effect be eliminated by any subsequent heat-treatment? 

Get yourself a nuts and bolt handbook from one of the more reliable suppliers. At least here in Sweden they supply all info about how and why and what. For free. I could also say that my professor taught me that when studying fasteners.

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Thanks for all of the input!  I returned the nut and bolt to my friend this morning, and he was impressed with the information y'all provided.  Maybe I'm off the hook for making one now.

 

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