[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: Soldering irons [was Re: gEDA-user: Free Dog meetings at MIT starting this September!]
On Aug 23, 2004, at 11:40 PM, Charles Lepple wrote:
Well...nobody comes to my lab to give sales pitches, but the details
ring true with what I see on the bench. I have an older, high-end
Weller iron (I don't recall the model number, the one with the digital
temp display) and putting it side-by-side with the Metcal I can say my
observed behavior matches that description.
The techical details sound right... or maybe someone gave the same
sales pitch at my lab :-)
Please remember that this is my understanding of what's going on in a
Metcal gained by lab heresay; I might always be confused about some
detail or another . . . .
A Metcal will give you the same amount of heat whether you are heating
a QFP lead or a wad of 12 gauge wires (unless you reach the wattage
limit for that particular tip). With a slightly less sophisticated
temperature-controlled iron, you may have to boost the temperature
setting slightly if there is a lot of thermal mass to whatever you are
Yes. The problem there, though, is that the thermal mass of whatever
you're soldering affects things much more with pretty much any other
make of iron. With the Weller irons, it seems they're depending on
having a larger thermal mass in the tip than what it's designed to
solder...because all that heat diffuses into what you're soldering, and
it takes so long for it to be replenished by the heating element.
The Metcal tips, on the other hand, seem to have very little thermal
mass...the heat being pumped into the joint being soldered was
generated pretty much "on demand".
It's interesting to strap a Type K thermocouple to the tip of an iron
and run it into a chart recorder while you're soldering. If you look
at the temperature profile of an older technology iron, you'll see the
temperature bouncing around quite a bit as you solder, and drop very
low when you solder something big. I tried this the first time I got
my Weller iron's tip *stuck* to the center conductor of an SO-239
connector...the tip temperature dropped below the melting point of the
solder and took a good twenty seconds to come back up so it could be
These crazy Metcal irons, however, just don't care. It's amazing
what they can do.
Dave McGuire "...it's a matter of how tightly
Cape Coral, FL you pull the zip-tie." -Nadine Miller