What in the world is this guy doing to his leaf springs?

MarkBC

MarkBC

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What is going on over in Nepal? Question 1 is why would you only replace the main spring and not the others? And question 2 is, it looks like he is able to bang them back into curvature with a hammer, so does that mean saggy springs can be brought back to life? Does this mean my old springs may have hope for a life beyond lawn decorations and scrap metal?

 
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Seth S

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You can have old springs re-arched. Basically you are bending and setting the spring steel to a new arched shape through some combination of cold working and possibly a heat treatment. Technically banging with a hammer is a form of cold working.
 
MarkBC

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He has a bunch of interesting how to videos. They do things a little differently over there. Some nice 60 porn too.

 
OSS

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When spring shops re-arch leaf springs in the USA, they use fire and heat it up until it gets orange. Obviously they don’t have that capability in that shop in Nepal
 
ace10

ace10

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....Question 1 is why would you only replace the main spring and not the others? ...[/MEDIA]

GDP per capita of Nepal = $1155 USD

GDP per capital of Canada $43240 USD
GDP per capita of USA = $63545 USD

Simple economic realities dictate that there is a massive chasm between our standards and their standards.
 
MarkBC

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Actually he has another video on a quick fix to weld the broken spring back together so it looks like he was just replacing that broken one. Interesting though how you can take the spring assembly apart and rejuvenate.
 
adamsfly

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I've never had springs come off or apart that easily. must be all that mud, Lol.
 
GeologistFelix

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Leaf springs are made of 5160, which sword nerds have been cold-working, grinding, and sometimes hot-forging into blades since they've been showing up in junkyards. From what I know about heat-treating 5160, it actually isn't probably all that difficult to 'properly' hot re-arch. What you need is about $500-600 in materials to build an electric kiln/forge that's big enough, and then probably a small feed trough full of used motor oil to quench it. 5160 is happiest right at its Curie Point, which the temperature when it stops being magnetic, but you could just look up the temp in C or F and set your thermostat to that and trust the machine, no magnet test. Then you just have to temper in your heat treat oven, again, for a few hours at something like 300-400 F (but you could look it up) to draw it back from fully hard (heh) and get stress concentrations to resolve while the metal is hotter and less brittle.

Obviously, you also need to wail on it with a hammer at some point, and good luck with that. I wouldn't trust my own blacksmithing skills, as more of an armchair enthusiast (so far!).

Worth it? I don't think so, personally, but I'd love to watch somebody go through all of this to re-arch their own springs in their garage if their video skills are up to snuff.
 
ferg

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Can't believe you guys didn't know this stuff. Or how easy it is to do. I don't own any automotive style power/air tools. Did all my work on my 40, mini, jeeps and work for others all with hand tools from a Craftsman 240 piece tool set. Just takes a litter longer.

Do any of you do your own work?
 
MarkBC

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What I don't quite understand is, isn't the constant flexing under use a form of cold working?
 
g-man

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I didn't think he was "re-arching" the springs. Just conforming the old one to the new one. Notice he beats on the old one and the new one and continues to line them up.
 
Seth S

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Can't believe you guys didn't know this stuff. Or how easy it is to do. I don't own any automotive style power/air tools. Did all my work on my 40, mini, jeeps and work for others all with hand tools from a Craftsman 240 piece tool set. Just takes a litter longer.

Do any of you do your own work?
Sometimes I have to put the lid on my coffee because Starbucks is busy. This counts right?
 
Seth S

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What I don't quite understand is, isn't the constant flexing under use a form of cold working?

1635947013317


Below is a generic stress vs strain curve for a generic material. A very common material test is a tensile test where a dog bone shaped piece of material is loaded into a special machine and then both ends are pulled until the part breaks into 2 pieces. The machine measures the amount of force applied to the part and it very precisely measures the deformation....essentially it measures the length of the part for the given force being applied.

here is a good video showing a tensile test:



In this graph:
1 to 2 is the elastic range - Basically how much a material will change shape and return to its original position without any internal impact to structure.
2 is your yield strength (the point that defines where you change from elastic to plastic deformation)
2 to 3 is your plastic deformation region
3 is your ultimate strength
3 to 5 is where you see necking in a tensile test....large changes to the shape followed by rapid failure.

Spring steel is desirable because it has a large elastic zone before reaching its yield point but generally at a cost of having a much shorter plastic deformation zone and often little or no warning to failure once the ultimate strength is reached. I'm sure someone else will comment and maybe explain better.

In layman's terms cold working basically makes a material stiffer at the cost of becoming more brittle.


1635948836750





1635947307205
 
Seth S

Seth S

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Can't believe you guys didn't know this stuff. Or how easy it is to do. I don't own any automotive style power/air tools. Did all my work on my 40, mini, jeeps and work for others all with hand tools from a Craftsman 240 piece tool set. Just takes a litter longer.

Do any of you do your own work?

A friend of mine comes from an incredibly creative family and one of his projects he made a crank handle gearbox for his engine stand. I believe he bought the gears themselves but he made his own crank handle, he made a wax core and his own sand mold. He made a small kiln and used pieces of aluminum from an old gearbox case...melted said aluminum down, poured into his mold, and cast his own drive box. then assembled everything....the final unit looked great and works very well. In standard form we all told him it was an incredible job while simultaneously telling him we hate him at the same time :rofl:
 
Seth S

Seth S

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What I don't quite understand is, isn't the constant flexing under use a form of cold working?

One additional point....Springs work in their elastic range and using them isn't a form of cold working. However a combination of use, hot, cold, wet, dry, salt, oil grime etc all likely contribute to material fatigue which slowly impacts the springiness of the springs themselves and results in sag. Fatigue as I recall is essentially the development if micro-cracks inside the structure of the material.
 

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