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Metcal - GT120 Soldering System with Heater Cartridge

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wickated:

--- Quote from: thm_w on June 12, 2021, 10:43:50 pm ---Feeding in faster could cause the tip temp to reduce more and control loop would pump more power in, giving an advantage.
In terms of overshoot, you can see from JBC's own 2009 measurements they can have significant ~20C overshoot. Ersa and weller are much worse (at least the models tested here). Metcal has no overshoot.
If you are doing mil-spec level soldering, sure you would care a lot.
If you are hobbyist, soldering big copper areas, most won't care about 20C of overshoot if it means the iron performs better.

--- End quote ---
to eliminate human error u should joint coin pretinned with known amount of solder instead of tinning it for first time.

dropping temp would not only say to pid to pump up power but also lead to slight overshoot. for example - highend jbc stations do profiled joint solder. cpu detects temp drop speed and suggests how big area is and give as much power as needed to make good solder joint. real tip temp would even be much hugher than set temp. this works better than standard pid which actually drop power when tip temp is near set instead of giving some more.
inductive metcall actually dont need this due to lack of feedback loop and pid, but metcall instead use extremely high temp tips - 400c is like standard. this often make them look much better. and metcall tips dont burn as fast as resistive tips, so 400c inductive tips wears like 350 resistive  one.

Shock:
My point was the importance of how mass comes into play, look at the size of the GT120 tip it's huge. The MX5200 appears to do a better job with far less mass. This test doesn't highlight the potential shortcomings (well aside from the T12 isn't so great).

It's why I think profiling the tips with temp measurement externally helps. The two most important things are temp and staying within target range. Mass (as I eluded to in my last post with the hot poker analogy) can be used as a crutch when soldering just a single target, it has a larger initial stored energy.

So recovery speed on successive joints as shown in the JBC charts will uncover shortfalls that make it hard to hide with mass. Since the GT120 seems slower than the MX5200 to heat up there evidence already it's power to mass is lower.

wickated:

--- Quote from: Shock on June 13, 2021, 01:30:19 am ---Since the GT120 seems slower than the MX5200 to heat up there evidence already it's power to mass is lower.

--- End quote ---
trick is not just power to mass, but power to temp delta. the less your temp drops, the more heat goes through. for example if i set 300c and just try to melt solid ton of copper, tip willl drain only 50 watt, but if i set 350c, power will rise to 70w. big tip internal mass means problems with heat transfer from heater to end, cuz you use copper tip material and drain surface you try to solder is copper too(so there always will be temp delta on tip end to heater core) . so fast feedback loop is better than huge mass - metcal has lower temp drop on tip end, its very little, but it makes sense.

SteveyG:

--- Quote from: Shock on June 12, 2021, 07:33:00 am ---You need to eliminate human error when testing I think. On the Metcal MX5200 your feed rate was slower so the mean external tip temp was higher.

--- End quote ---

Not sure how you've come to that conclusion or whether we're talking about different things - The feed rate was as fast as possible. The irons with the slower feed rate were not melting the solder as quickly, but the MX5200 certainly didn't have the slowest feed rate. In the earlier video the criticism was that the faster feed rates were of benefit to the heating of the coin.  :-//

It's not a scientific test of course, and real-world soldering is rarely so demanding.

thm_w:
New white paper on the GT90 and GT120.
Would be nice if they tested against the older stations, but, its against some "unnamed" competitors.

The test setup they used isn't terribly complicated. They use large chunks of copper, and wait until the temperature reaches a setpoint:


They say "tip or cartridge" but they obviously are using their own cartridge design to get the best performance.





The unnamed competitors, my guess in brackets:
- A) 90W tip style (Weller WTP90) Weller WT1010
- B) 75W cartridge style (Hakko FX951)
- C) 150W tip style (Ersa i-con 1) Weller WT1010H
- D) 140W cartridge style (Hakko FM-2030)


If the 140W is the JBC, then it may not be capable of 140W, in one of SDG's videos he said it limited the output to 90W. You probably have to use T470 to get the full 140W. Sadly JBC does not make this clear in their documentation, that I can find, they just say "140W peak" for the base unit.

edit: the 140W could be a Hakko too, didn't realize they had a 140W handle.

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