Big soldering irons don't run hotter?

[Zak]

I had always lived in the belief that a 15W soldering iron ran cooler
than a 35W iron but recently I read something which said they both
run at the same temp.

Presumably the real difference is the speed at which the iron reheats
once the thermostat kicks in to say the iron is too cool.

I'm in the Uk and I currently use a 25W Antex. It seems to "run out
of heat" all too often when I am soldering undemanding things like a
fine wires to small tag.

If the temp is the same then would I be ok using something like a 35W
iron even for working on electronics components.

 

[Tim Williams]

I had always lived in the belief that a 15W soldering iron ran cooler
than a 35W iron but recently I read something which said they both
run at the same temp.

Depends on size. If you plug in two irons, 30 and 40W, both the same size,
the 40W iron is always going to run hotter. The $10 Radio Shack irons
available around local stores have basically only one difference and that's
the element and tip size. As such, the 40W runs a lot hotter, increasing
tip loss and risk of overheating things. On the other hand, it makes
quick(er) work of soldering heavy wire and desoldering most anything.

Those big 100-300W irons (often used for soldering sheetmetal) are well,
big. They don't need to vaporize the solder, just melt it. The rest of the
power is there to keep the thing at that temperature, and speed up heating
when you suck out heat with some work.

Soldering guns typically run a whole lot hotter, but only if you clamp it
down on max with nothing to melt. Best idea with these is to get good at
clicking the switch on and off to regulate temperature.

Tim

 

[repatch]

I had always lived in the belief that a 15W soldering iron ran cooler than
a 35W iron but recently I read something which said they both run at the
same temp.

Presumably the real difference is the speed at which the iron reheats once
the thermostat kicks in to say the iron is too cool.

I'm in the Uk and I currently use a 25W Antex. It seems to "run out of
heat" all too often when I am soldering undemanding things like a fine
wires to small tag.

If the temp is the same then would I be ok using something like a 35W iron
even for working on electronics components.

Actually it depends on what iron it is.

Temperature unregulated irons can vary greatly on the temperature they get
to. Wattage alone is not a good indicator of whether one iron will be
hotter then the other.

Temperature regulated irons hold the temp they are set to. In that case
the wattage will determine how MUCH heat can be applied to whatever is
being soldered. Generally the more material you are trying to heat, the
more powerful an iron you need.

In your case I would strongly recommend getting a temp regulated model.
The wattage you need will then depend on what you want to solder. From
your comment "soldering undemanding things like a fine wires to a small
tag" I'd say something in the 50-75W range will suit you perfectly
(overkill for the small tag, useful when soldering bigger things).

The best part about temp regulated irons is they won't heat small things
up to much, something a temp unregulated iron will do.

TTYL

 

[Charles Schuler]

I had always lived in the belief that a 15W soldering iron ran cooler
than a 35W iron but recently I read something which said they both
run at the same temp.

Presumably the real difference is the speed at which the iron reheats
once the thermostat kicks in to say the iron is too cool.

I'm in the Uk and I currently use a 25W Antex. It seems to "run out
of heat" all too often when I am soldering undemanding things like a
fine wires to small tag.

If the temp is the same then would I be ok using something like a 35W
iron even for working on electronics components.

Larger irons usually have a larger thermal mass and thus need more watts to
recover in a reasonable length of time. The larger thermal mass allows them
to handle larger jobs ... such as sheet metal or large wires and terminals.

Ideally, the unloaded temperature (not in contact with any work) should be
about the same regardless of the watts.

 

[Roger Hamlett]

I had always lived in the belief that a 15W soldering iron ran cooler
than a 35W iron but recently I read something which said they both
run at the same temp.

Presumably the real difference is the speed at which the iron reheats
once the thermostat kicks in to say the iron is too cool.

You are assuming the iron has a thermostat. Basic units don't. Just like a
basic electric 'bar' fire, they heat up and stabilise at the point where
the heat loss from the iron, matches the input power.

I'm in the Uk and I currently use a 25W Antex. It seems to "run out
of heat" all too often when I am soldering undemanding things like a
fine wires to small tag.

If you are doing a lot of joints in succession, with an unregulated iron,
then the tip will get cooler with each one. Also, you must be careful to
be using the right solder. The iron will have a 'design' temperature, and
some solders will require less heat than this, while others require more.

If the temp is the same then would I be ok using something like a 35W
iron even for working on electronics components.

Get the smallest shafted temperature controlled iron you can find. Two
basic designs, 'single temperature' units, like the Antex TCS50 (trimmable
with a screwdriver), or fully adjustable units, like the 660TC, with the
TC50.
Antex irons give better heat transfer to the joint (I also use a 100W
Weller TC iron, and the Antex 50W will out solder it on some jobs), than
many competing designs, and I like the weight.

Best Wishes

 

[William P.N. Smith]

I'm in the Uk and I currently use a 25W Antex. It seems to "run out
of heat" all too often when I am soldering undemanding things like a
fine wires to small tag.

Get a regulated one like a Weller WTCPN(?), and you can choose you tip
size for the job, and select temperature by swapping tips.

$45 on eBay.

 

[Palindr☻me]

I had always lived in the belief that a 15W soldering iron ran cooler
than a 35W iron but recently I read something which said they both
run at the same temp.

Presumably the real difference is the speed at which the iron reheats
once the thermostat kicks in to say the iron is too cool.

I'm in the Uk and I currently use a 25W Antex. It seems to "run out
of heat" all too often when I am soldering undemanding things like a
fine wires to small tag.

If the temp is the same then would I be ok using something like a 35W
iron even for working on electronics components.

As others have said, irons come as uncontrolled or temperature controlled.

The temperature of an uncontrolled iron is dependant on the wattage and
ambient conditions. Wave one around in the air and it will be
substantially cooler than if you put it in an insulated stand. One of my
irons is 250W, uncontrolled, and will soon start to glow red-hot, unless
in contact with a LOT of metlwork being soldered. Great if you are doing
plumbing - not so great for electronics work. The tip is about 1 1/2"
across. It dates back to the 1940s - they may not be avialble
anymore...I got given it by my great uncle, an RN submariner electrician
in WWII.

The temperature of the tip of a controlled iron in its stand should be
near enough the set temperature, irrespective of iron wattage. Once you
start using it, the tip temperature will fall. The key point is how much.

The end of a very long, thin, tip, in contact with a large chunk of
cold metal, will quickly fall in temperature and stay at that low
temperature. It is simply not possible to transfer enough heat down a
very long thin tip, irrespective of the wattage of the iron. So, if you
only use very long thin tips, practically any wattage of iron will do.
I have a very tiny 15W temperature controlled iron which is as
comfortable and easy to use as a 'scope probe. The element tube is about
1/8" in diameter and so is the thickest part of the tip.

However, if you have an iron with interchangeable tips and can use a
thick, short, tip, then the tip is capable of transferring much more
power - so you can make good use of a higher wattage iron. Hence my next
bigger iron up from the teeny one is a 40W. The element tube is about
1/4" in diameter and so is the thickest part of the tip. But the
business end varies from something about 1/16" across for one tip to
1/4" across for another.

I could do with something to fill the gap between the 40W and 250W - I
sometimes end up with an iron in each hand and feeding solder in from a
tube clenched between my teeth...

I reckon that it is the tip that makes the iron. My favourites are a
weller 40W that takes interchangeable tips, each tip with a preset
temperature. But there are places where those irons are simply too big
or too small.

I have a Maplin www.maplin.co.uk BP53H soldering station that I hate -
I can't get along with any of the tips. Unlike plain copper tips, you
can't just shape them the way you want. They also do a very cheap one
N78AR, which I haven't tried. It may be worth a look - it's a 50w
variable temperature adjustable model for <13GBP.

 

[Roy L. Fuchs]

Actually it depends on what iron it is.

Temperature unregulated irons can vary greatly on the temperature they get
to. Wattage alone is not a good indicator of whether one iron will be
hotter then the other.

Not true. An UNregulated Iron IS related to heat output by wattage.
Almost directly and proportionally.

So a 35W will be MUCH hotter, and almost always physically bigger than
a 15W. The 15W is akin to a bench assemblers model, and the 35W is
typically akin to someone doing stained glass that needs to dump a LOT
of heat into a connection or seam without dropping the iron temp much.

Temperature regulated irons hold the temp they are set to.

No... really? :-]

In that case
the wattage will determine how MUCH heat can be applied to whatever is
being soldered.

They are usually limited by the tip shape and size. It is very hard
to fill a small, long, thin tip with enough heat to say... solder a
shield can seam onto a PCB. Place a larger tip in the same Iron
though, and input consumption will go up (and thus output) when trying
to do the same task.

Generally the more material you are trying to heat, the
more powerful an iron you need.

OR the larger thermal mass at the tip (read tip size).

In your case I would strongly recommend getting a temp regulated model.

For electronic PCB mixed technology assembly... definitely.

The wattage you need will then depend on what you want to solder. From
your comment "soldering undemanding things like a fine wires to a small
tag" I'd say something in the 50-75W range will suit you perfectly
(overkill for the small tag, useful when soldering bigger things).

50 to 75 Watts seems huge for PCB soldering irons. A regulated unit
may rate that on its consumption label, but the tool itself will never
use that much (short of huge desoldering tips being applied).

The best part about temp regulated irons is they won't heat small things
up to much, something a temp unregulated iron will do.

Again, that depends on the thermal mass (goes with physical mass) of
the tip itself. It gets pulse modulated (pumped) by the station.Once
up to temp, a large tip is quite capable of dumping a huge amount of
thermal energy into the work.

 

[David Peters]

I reckon that it is the tip that makes the iron. My favourites
are a weller 40W that takes interchangeable tips, each tip with
a preset temperature. But there are places where those irons
are simply too big or too small.

I have a Maplin www.maplin.co.uk BP53H soldering station that I
hate - I can't get along with any of the tips. Unlike plain
copper tips, you can't just shape them the way you want. They
also do a very cheap one N78AR, which I haven't tried. It may be
worth a look - it's a 50w variable temperature adjustable model
for <13GBP.

That Maplin soldering iron (ref N78AR) seems like rather a good
deal at 13 GBP.

However you say you are unhappy with your other Maplin iron so I
will ask if anyone has used one of these bargain temperature
controlled irons.

Maplin refers to it as an "LS20 Solder Station".
See http://tinyurl.com/lunbf for full details

 

[JANA]

The wattage rating would be more of the heating capacity. The larger the
wattage, the greater the mass that it can heat. Use a lower wattage for the
smaller jobs. Use a higher wattage for the larger type soldering jobs.

--

JANA
_____


I had always lived in the belief that a 15W soldering iron ran cooler
than a 35W iron but recently I read something which said they both
run at the same temp.

Presumably the real difference is the speed at which the iron reheats
once the thermostat kicks in to say the iron is too cool.

I'm in the Uk and I currently use a 25W Antex. It seems to "run out
of heat" all too often when I am soldering undemanding things like a
fine wires to small tag.

If the temp is the same then would I be ok using something like a 35W
iron even for working on electronics components.

 

[Dave D]

That Maplin soldering iron (ref N78AR) seems like rather a good
deal at 13 GBP.

However you say you are unhappy with your other Maplin iron so I
will ask if anyone has used one of these bargain temperature
controlled irons.

I have one, now non-working! I used it all of three times at 3/4 max setting
and it burned out. They are rubbish- they're not temperature controlled-
they're simply a tacky, clumsy, cumbersome mains iron hardwired into a
lightweight, cheap plastic dimmer box. There's no thermostat, you simply
have to whack up the 'dimmer' knob when the tip temperature drops, and the
iron seems very inefficient- more like a 30W than a 50W.

My advice to anyone wanting a temperature controlled iron is to look out for
proper temperature controlled irons on eBay, or better still a low voltage
soldering station like the Weller TCP series or Antex 660 with a TC50 iron.
They cost a lot more even secondhand, but they are immeasurably superior in
every way. I have both and can't fault them at all.

Dave

 

[Ed Bailen]

I think the OP was closer. The wattage rating is the ability to
recover once the heat has dropped. The heat capacity is a function of
the mass of the tip.

When soldering PL-259 connectors, or homw-made brass boxes, I use a
roofer's iron. The tip is a slug of copper about one inch in diameter
and over 3 inches long. It takes about 30 minutes to come up to
temperature, but anything you touch it to is instantly at soldering
temperature.

 

[distar97]

We've seen some good thoughts on soldering irons. I learned that
wattage is a unit of capacity. Temp is important but you also
need wattage to match the job. After all, the temperature of
the spark in your cars ignition is in the thousands but the
wattage is way too low to melt solder (in normal sizes)
Let me offer a simple analogy about wattage. If a common match will
raise a one inch strip of metal to a certain temperature, would it not
require 12 matches to raise a 12 inch strip of metal to the same temp,
placing one match at each inch of the strip.
Keep in mind the temperature of the matches are generally some
consistent number, so it is clearly the higher wattage of the 12
matches
as a whole that makes the difference between one match and 12.

More important than the physics of the issue, experience really
makes a difference. You'll find using a similar soldering station like
my old Weller WTCPN make a world of difference. It's undersized for big
jobs but perfect for circuit board work. The temp controlled tips
click on and off as necessary. For bigger work, I use a higher wattage
station not neccesarily a higher temp tip, all else being equal.

Dennis H.

 

[Tim Williams]

Let me offer a simple analogy about wattage. If a common match will
raise a one inch strip of metal to a certain temperature, would it not
require 12 matches to raise a 12 inch strip of metal to the same temp,
placing one match at each inch of the strip.

Not really, convection and geometry being what they are, it'll be hotter in
the center because the heat can't really "get out", while on the edges, the
heat just rolls up and away. But that's just being pedantic; ignoring such
effects, yes, you're absolutely right, power per area is temp, roughly
speaking.

More important than the physics of the issue, experience really
makes a difference. You'll find using a similar soldering station like
my old Weller WTCPN make a world of difference. It's undersized for big
jobs but perfect for circuit board work. The temp controlled tips
click on and off as necessary. For bigger work, I use a higher wattage
station not neccesarily a higher temp tip, all else being equal.

I should build an induction heated soldering iron. I've heard of Weller
irons that work like that. Mmmm, isolated tip. Tack on a thermocouple and
I've got it made.

Tim

 

[Roy L. Fuchs]

We've seen some good thoughts on soldering irons. I learned that
wattage is a unit of capacity. Temp is important but you also
need wattage to match the job.

Just to keep up at a given reasonable time rate actually. The at
rest temperature is one thing. The thermal mass (size) of the tip is
another. If it cannot maintain the "at rest temp" very well, then the
wattage used to heat it is not sufficient for the tip's mass or rate
of radiation (emissivity).

 

[ampdoc]

I've used Weller, and while they have a good product, I much prefer the
inexpensive Hakko unit, the 635. Adjustable temp, quick heat, and if well
cared for the tips last forever.

 

[Roy L. Fuchs]

I've used

USE your brain. LEARN to conform, and refrain from top posting in
Usenet.

http://en.wikipedia.org/wiki/Toppost

Your best bet is to get a REAL news client, and get rid of OutHouse
Express as your method of reading Usenet news articles.

 

[Zak]

I've used Weller, and while they have a good product, I much
prefer the inexpensive Hakko unit, the 635. Adjustable temp,
quick heat, and if well cared for the tips last forever.

Do you have a link for this product. I can't seem to locate it.

Is it available in the UK?

 

[Zak]

I have one, now non-working! I used it all of three times at 3/4
max setting and it burned out. They are rubbish- they're not
temperature controlled- they're simply a tacky, clumsy,
cumbersome mains iron hardwired into a lightweight, cheap
plastic dimmer box. There's no thermostat, you simply have to
whack up the 'dimmer' knob when the tip temperature drops, and
the iron seems very inefficient- more like a 30W than a 50W.

My advice to anyone wanting a temperature controlled iron is to
look out for proper temperature controlled irons on eBay, or
better still a low voltage soldering station like the Weller TCP
series or Antex 660 with a TC50 iron. They cost a lot more even
secondhand, but they are immeasurably superior in every way. I
have both and can't fault them at all.

Thnak you for the warning!

 

[Zak]

Get the smallest shafted temperature controlled iron you can
find. Two basic designs, 'single temperature' units, like the
Antex TCS50 (trimmable with a screwdriver), or fully adjustable
units, like the 660TC, with the TC50.
Antex irons give better heat transfer to the joint (I also use a
100W Weller TC iron, and the Antex 50W will out solder it on
some jobs), than many competing designs, and I like the weight.

This is the Weller page for the UK

http://www.cooperhandtools.com/europe/spare_parts/weller/index.htm

but which iron in the drop down box is the best value?