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Author Topic: why do soldering irons go hotter at the tip, than the shaft?  (Read 5938 times)

paul.fr

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why is that?


 

Offline lightarrow

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #1 on: 06/10/2007 07:54:27 »
why is that?
My knowledge of english language is limited. What do you mean exactly with "irons", "shaft" and how exactly do you sold them?
 

paul.fr

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #2 on: 06/10/2007 08:13:06 »
why is that?
My knowledge of english language is limited. What do you mean exactly with "irons", "shaft" and how exactly do you sold them?

This is a link to a nice picture of a soldering iron:
http://microtorches.ayay.com/Soldering%20Iron%20solder.jpg

without meaning to sound rude, the shaft would be the...ermm..the tip is at the end of the shaft. Imagine a pencil, the bit you hold is the shaft and the part you write with is the tip. Hope that explains it well enough.
 

Offline lightarrow

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #3 on: 06/10/2007 13:43:33 »
why is that?
My knowledge of english language is limited. What do you mean exactly with "irons", "shaft" and how exactly do you sold them?

This is a link to a nice picture of a soldering iron:
http://microtorches.ayay.com/Soldering%20Iron%20solder.jpg

without meaning to sound rude, the shaft would be the...ermm..the tip is at the end of the shaft. Imagine a pencil, the bit you hold is the shaft and the part you write with is the tip. Hope that explains it well enough.
Ah, ok, with "soldering irons" you intended the name of the instrument, not the action of soldering "irons" :)
Forgive me, I didn't know that's the name of that device.

However it depends on how the instrument (also called welder) works. I assume you talk about the electric one. The electric resistance, covered with electrically insulated material, is inside the tip; furthermore, the metallic part which connects the tip to the shaft (= handle) is made of non very thermical conductive material. For this reason the metallic part inside the shaft (usually made of plastic) doesn't reach high temperatures (which would melt the shaft and burn your hand).
 

lyner

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #4 on: 06/10/2007 22:53:04 »
Some soldering irons manage to get the tip hotter than the shaft because the shaft may be a bit insulated or even made of shiny  stainless steel.   The main reason that the tip will melt the solder easier is because it is either copper or it is plated with a metal that amalgamates easily with the solder and 'wets' easily (the solder in contact, initially, melts) and then there is a good thermal contact which aids more heat flow just where you want it.
The shaft soon gets oxidised and will just not show any interest in the solder at all. It can still burn your hand badly!
The word 'welder' would usually be reserved for an instrument  using aflame or electric arc to melt the metals to be joined. Soldering would normally involve a low melting point alloy which sticks to each side and then solidifies.  Brazing is a form of high temperature soldering. Soldering / brazing  will produce not as strong a joint  as welding, usually.
English is a barmy language, isn't it?
(What's 'barmy' in Italian?)
 

Offline eric l

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #5 on: 07/10/2007 10:10:51 »
English is a barmy language, isn't it?
(What's 'barmy' in Italian?)
It's so barmy that the spelling control does not recognize it and that I, too had to look up that word in the dictionary to make sure (allthough I was not too far off deriving it from the context)
 

Offline lightarrow

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #6 on: 07/10/2007 11:06:29 »
Some soldering irons manage to get the tip hotter than the shaft because the shaft may be a bit insulated or even made of shiny  stainless steel.   The main reason that the tip will melt the solder easier is because it is either copper or it is plated with a metal that amalgamates easily with the solder and 'wets' easily (the solder in contact, initially, melts) and then there is a good thermal contact which aids more heat flow just where you want it.
The shaft soon gets oxidised and will just not show any interest in the solder at all. It can still burn your hand badly!
The word 'welder' would usually be reserved for an instrument  using aflame or electric arc to melt the metals to be joined. Soldering would normally involve a low melting point alloy which sticks to each side and then solidifies.  Brazing is a form of high temperature soldering. Soldering / brazing  will produce not as strong a joint  as welding, usually.
English is a barmy language, isn't it?
(What's 'barmy' in Italian?)

Thank you very much for this technical english lesson  :)

With "barmy" I found different meanings. You mean "foamy" or "that became bigger with time" ? (I also found a third meaning, that is, "not very intelligent", but I assume you didn't refer to it).
In the first case, in italian is schiumoso; in the second case is lievitante.
Bye.
Alberto.
« Last Edit: 07/10/2007 11:10:43 by lightarrow »
 

Offline techmind

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #7 on: 07/10/2007 12:34:36 »
Why do soldering irons go hotter at the tip, than the shaft?
why is that?
I'm not being facetious, but what makes you think irons are hotter at the tip than the shaft?

A common electric soldering iron comprises a plastic handle, a thin tubular metal shaft within which is a coiled heating element. The "bit" (that's what it's called - the assembly which includes the tip you actually solder with) then fits snugly onto the shaft containing the heating element - and often has a springy clip around it to help ensure good thermal contact.

Since the source of the heat is the element within the shaft, the tip cannot be hotter than the shaft.

In answer to my initial rhetorical question, I suggest that perhaps the "evidence" you have it that the solder only really melts on the very tip of the iron. This effect is caused not by the lack of temperature elsewhere, but that the solder will not "wet" the heavily-oxidised shank of the iron. If it can't wet it, then the thermal conductivity to the solder will be poor and you won't get it to melt.

As an aside, on the first occasion you ever use a new soldering iron (or soldering-iron bit) you are advised to continuously attempt to feed solder onto the bit as the iron heats for the first time. This is important to "tin" (coat with solder) the bit before it oxidises (things oxidise very much quicker when hot). If you fail to do this, you'll find the solder doesn't want to stick to the bit, and will form a bead, and the iron generally won't do its job very well. If you have an iron with this problem then you need to clean the tip using a mild abrasive (although the bit is made of copper they are often iron-plated, and you don't want to wear through the iron-plating -- don't use a file!). Then, as the iron heats up for the first time after cleaning, keep "scratching" the solder against the tip until it melts and coats the tip.
« Last Edit: 07/10/2007 12:39:45 by techmind »
 

Offline lightarrow

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #8 on: 07/10/2007 14:08:22 »
Why do soldering irons go hotter at the tip, than the shaft?
why is that?
I'm not being facetious, but what makes you think irons are hotter at the tip than the shaft?

A common electric soldering iron comprises a plastic handle, a thin tubular metal shaft within which is a coiled heating element.
Yes, but in that kind the heating element is near the tip, not near the handle. The low thermal conductivity of the (usually) stainless-steel shaft reduces the temperature of the shaft near the handle.
 

lyner

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #9 on: 07/10/2007 22:22:04 »
Barm, in English, is a word for the frothy surface of a liquid  (beer)which is fermenting. But, colloquially, barmy means daft, dumb, mentally unbalanced - the result of consuming alcohol, perhaps.  I think your third meaning was nearer what I was getting at, Lightarrow.
English constantly mixes it Nouns and Verbs- , using gerunds a lot. So  a walking stick does not walk - "I saw a man eating fish in a restaurant" does not mean there was a shark in there.

btw, where does your name 'lightarrow' come from - or is this too personal information?
Sophiecentaur refers to my aged Yacht - a Westerly Centaur, name of Sophie.
Cheers
Andrew
 

Offline lightarrow

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #10 on: 08/10/2007 15:44:37 »
Barm, in English, is a word for the frothy surface of a liquid  (beer)which is fermenting. But, colloquially, barmy means daft, dumb, mentally unbalanced - the result of consuming alcohol, perhaps.  I think your third meaning was nearer what I was getting at, Lightarrow.
English constantly mixes it Nouns and Verbs- , using gerunds a lot. So  a walking stick does not walk - "I saw a man eating fish in a restaurant" does not mean there was a shark in there.

btw, where does your name 'lightarrow' come from - or is this too personal information?
Sophiecentaur refers to my aged Yacht - a Westerly Centaur, name of Sophie.
Cheers
Andrew
(I thought you were a lady! [:I])
English language is very interesting, thank you for the informations.
"Lightarrow" comes from the fact someone, one day, told me that the purpose of my life is to show to the others the path to light. Never started, however.  :)
 

lyner

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #11 on: 08/10/2007 16:36:50 »
You're not doing badly as an arrow of educational light!
You have put a lot of people straight on several occasions.
I do have a profile - that tells people my gender.
Funny but you are not the first person on this forum with a Scientific mind to have made the same assumption.
 

Offline lightarrow

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #12 on: 08/10/2007 20:36:52 »
You're not doing badly as an arrow of educational light!
You have put a lot of people straight on several occasions.
I do have a profile - that tells people my gender.
Funny but you are not the first person on this forum with a Scientific mind to have made the same assumption.
Touchè!  :)
 

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why do soldering irons go hotter at the tip, than the shaft?
« Reply #12 on: 08/10/2007 20:36:52 »

 

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