Choosing a soldering station

[KJ6EAD]

I kind of like the "fun" look. Even if work is boring, tools don't have to look that way Besides, the 888 is more compact than the 936.

They make the FX-888 in three other colors including black but those colors aren't available in the U.S.

Hakko discriminates color on the basis of nationality.

https://www.hakko.com/english/products/hakko_fx888.html

 

[RichTheDude]

Still using a Weller TCP here (temperature set by the bit and a magnet on the end of it).

Have some Antex's at work (SD50) but changing the bits is a bit of chore on those compared to the weller or the iron you have brought - looks indentical type of bit changing process.

I love the Weller TCP's build quality but it would be neat to have control of the temperature.

 

[Reloadron]

So would the thermocouple seen in the photo I attached in my last post be considered large or small? I don't have any frame of reference.

Back there I mentioned thermocouple using AWG 30 gauge TC wire. AWG 30 has a wire diameter of .010 inch or .254 mm so from what I see the pictured TC is too big. Also, this is not quite an exacting science. The goal is not a calibration to within fractional parts of a degree. Today was busy so I never got a tip brazed but will have some images later I hope. Now it is about time to get out of here. Gawd, I love Mondays.

Ron

 

[timelessbeing]

this is not quite an exacting science. The goal is not a calibration to within fractional parts of a degree.

So should still be able to get within a few degrees by putting that thermocouple in a blob of solder big enough to envelope it or what?

 

[Reloadron]

So should still be able to get within a few degrees by putting that thermocouple in a blob of solder big enough to envelope it or what?

Yes, pretty much so. What they generally shoot for is a tip temperature that is +/- 10 degrees F of set point. So if I set my unit for let's say 500 F anywhere between 490 and 510 is fine. Granted the TC being used and the system used to measure likely aren't calibrated but it isn't like we are trying to meet some ISO standard for aerospace or nuclear engineering. Place the tip on the TC and try adding a little solder, the solder only being there as a thermal mass and to allow some thermal conductivity. Is that the preferred method? Hell no but for what we are doing it is good enough.

Soldering is a skill. The more someone does it the better they become at it. When you have done it long enough believe me you know if the heat is good. You can tell by the flow of the solder. You just develop a knack for it.

Always remember when working with small components, "the bigger the blob, the better the job".

Maybe later I'll get some images posted.

Ron

 

[saturation]

An an option is stock some eutectic lead free solder, for example Sn96.3Cu0.7 has a melting point of exactly 227C so you can check if the lower range of your iron's knob is pointing to that portion of the scale; once that is set, the whole scale is calibrated. You can then not worry about the thermocouple and the technique of measurement. I'm not sure how much more accurate it is over the recommended thermocouple method, but it is easier and it will definitely point your scale to the ball park area. It needn't be ISO, military or aerospace quality, but methinks good enough for home labs so we know that the 350C mark is right.

Note, eutectic leaded solder has melting points below 200C, it may not be high enough to register on many adjustable station scales, but the lead free is nearly all above 200C.

 

[saturation]

If the graphs are true, the FX 888 is an improved 936, faster heat cycle and more efficient tips in terms of heat conduction. BTW, many new efficient tips fit the 936 per the literature, so older 936 users can benefit from the upgrade.

I rushed out and bought a 936 as the FX888 was being introduced because I didn't want to lose getting one; I prefer my gear be stackable for storage. The cutie look is fine, but in addition you get the brass wool and rubber cleaner tip cleaner, which you pay extra for if you bought a 936.

They make the FX-888 in three other colors including black but those colors aren't available in the U.S.

Hakko discriminates color on the basis of nationality.

https://www.hakko.com/english/products/hakko_fx888.html

 

[saturation]

Yes, unfortunately, if you don't have the right size thermocouple or its worn, or has a thick oxide coat, it may repel the solder blob. The eutectic solder method is probably easier to implement beyond buying a Hakko 191 tip thermometer [ I see them on eBay for $15, delivered with 10 thermocouples.]

Also, using a thermocouple also depends on the size and shape of your tip. If its conical, or very small, it can be easy to tin but the blob could easily roll off and not really cover the sensor wires.

This is what I attempted to do using my DMM and temp probe. However the solder was repelled by the thermocouple, even with flux.I kind of like the "fun" look. Even if work is boring, tools don't have to looks that way Besides, the 888 is more compact than the 936.

 

[saturation]

All the quality soldering standards, set temps pretty much to ~ 350C or lower [ +/- margin for variation within the standards, but definitely not about 400C]. Thus, the fixed temp camp lead by Metcal argue what's to adjust? There are temp scales for different needs, ~ 300C for SMT sized parts, and ~ 400C for large wires or connectors, but none in between. The induction type heat used in Metcal tips are very consistent and constantly adjusts power output to maintain tip temp regardless of the tip load, such as small solder points to points in large ground planes. There is no calibration for such soldering stations. The temp sensor, heater and tip are one piece. Other technologies work differently, but are built around the philosophy of fixed temps.

OTAH, the adjustable camp uses cheaper low tech separate heater units and tips, both of which wear unevenly with use; thus the need to recalibrate. It may be worn to the point the temp provided at the tip is off but the tip is still usable. There is also no sensor on the tip, its on the heater or the tip body, and the scale and adjustment assumes the calibrated heat output of the station is fully and evenly transmitted to the tip. So the adjustment is really there to extend the life of a workable tip, foremost, than to adjust heat for soldering purposes. This is typified by the Hakko 936 or the Weller WES51.

There are also stations that are both adjustable and have direct tip temperature feedback and such stations are not calibrated either, and cost more than the Hakko 936.

Both the adjustable have locks to fix the station temps, so the user cannot adjust them which I presume are used in commercial production soldering situations, to emulate what the Metcal folks do.

So who is right? I don't know. But for home lab needs, the Hakko 936 types are the cheapest stations to meet soldering standards, so it provides both the ability to give the lowest heat to solder and maintain tip life, while being the lowest cost. We know for certain were the floor is in terms of modern soldering irons for best outcome, but the ceiling and benefits of moving up depends on what you are willing to spend for a need. For example, the costly stations don't require calibration, so it saves the owner/user the hassle, this can be large if you have many stations and find out the calibration is off when product defects starting popping up or the ISO inspector finds out and cites you; or if you solder a huge volume the difference is tip life between a Metcal and a Hakko 936 may start to become economically feasable.

Still using a Weller TCP here (temperature set by the bit and a magnet on the end of it).

Have some Antex's at work (SD50) but changing the bits is a bit of chore on those compared to the weller or the iron you have brought - looks indentical type of bit changing process. I love the Weller TCP's build quality but it would be neat to have control of the temperature.

 

[saturation]

The idea is that the drastic cooling of a hot tip caused by a water cooled sponge can cause microfractures in the tip; recall that the iron coating on a copper tip is relatively thin. If fractures make its way down to the copper, the flux + heat with start to eat the copper up, and thus, reduce the life of your tip. If you have a tip that is eroded more on the inside on the tip than the outside, chances are it had such a microfracture. It may not happen when the tip is new, and the iron coat is at its thickest, but will matter more when its more worn. Also, build up of contaminants on the sponge, if not the water you use, can retain the flux elements that will continue to wear the tip.

Hakko introduced the brass wool cleaner which obviates this problem. Also heat resistant rubber does the same, and both are provided with the FX 888 station as alternative cleaning methods and many newer solder stations, such as by Weller.

If you have such available already, avoid using the sponge. There has never been a formal study to compare sponge vs wool, but if you have the wool, what's there to lose? It cost about the same.

Note, its brass or bronze, not steel as sold by some cheap Hakko copies. The Hakko original is brass because its softer than the iron coat of the tip, and will not scratch it [unless you abuse it!] the Hakko wool is also coated with rosin. You can of course, make your own as brass wool is sold in hardware stores, just find a way to coat it with rosin.

I would really like to do some reading on this.

I do use the wet sponge method using my cheap $50 Weller but it seems as if the tip is bending a bit over 2 years of use and I don't apply any pressure at all!

 

[timelessbeing]

An an option is stock some eutectic lead free solder, for example Sn96.3Cu0.7 has a melting point of exactly 227C

OK, correct me if I'm wrong, but if you set your iron to 228, the solder won't melt. Or even 250. 300 yes but it will take some time. The higher the temp, the quicker it melts. Also, 0.6mm solder will take less time to melt than 1.5mm.

 

[saturation]

Your suspicion is right for soldering parts.

But, the short story is, I've tested it in the past, 0.5mm wire will melt quickly at the right temp.

Thicker wire depends on how the extra wire mass heat sinks the tip energy, and what the ambient room temp is. It will be off a few degrees, but it too will certainly melt but not as quickly, at least for typical solder wire. I think I've used up to 1mm.

The heated area is fairly small on a solder tip, and a reason for the higher setting on your station is because heat conductive material heat sinks the tip temp and 'steals' the energy away, so the tip is kept higher to compensate for the anticipate loss from heat sinking. But if the solder is placed directly on the tip, there is little heat sinking effect, except for the size of the solder wire itself. In this Hakko fx888 ad, the drop shown is typical, about 100C.



The reason for molten solder on the tip when using a thermocouple is to disperse the heat evenly on the wires, and increase the contact surface area. Both wires of the thermocouple have to heated 'evenly' as best possible.

In the prior posts I wrote that 350C as an almost 'universal' setting for adjustable iron temp, if you don't want to tweak it for different conditions, it will work regardless of the tip geometry, from tiny cones, to the largest chisel available for that iron, and used for most size pads. But in reality you need more energy for small tips and less for larger tips, smaller tip have less contact area to inject heat as a larger tip, so you could reduce the temp for larger tips, say to 300C for leaded solder, and thus optimize tip life and still have the right heat for soldering. For lead free you may have to adjust this up to 330C depending on how much heat is actually sunk by the PCB tracing and components.

OK, correct me if I'm wrong, but if you set your iron to 228, the solder won't melt. Or even 250. 300 yes but it will take some time. The higher the temp, the quicker it melts. Also, 0.6mm solder will take less time to melt than 1.5mm.

 

[Mr RB]

The idea is that the drastic cooling of a hot tip caused by a water cooled sponge can cause microfractures in the tip; recall that the iron coating on a copper tip is relatively thin. If fractures make its way down to the copper, the flux + heat with start to eat the copper up, and thus, reduce the life of your tip. If you have a tip that is eroded more on the inside on the tip than the outside, chances are it had such a microfracture. It may not happen when the tip is new, and the iron coat is at its thickest, but will matter more when its more worn. Also, build up of contaminants on the sponge, if not the water you use, can retain the flux elements that will continue to wear the tip.
...

Yep, and not just the chance of fracturing but the metal fatigue makes the tip frosty and less able to be wetted, than a good polished tip.

I've been using the "aerated solder blob" technique (which to my knowlege I invented) since the late 1980's when wet sponge was actually considered to be the "proper" way to clean a tip.

I have tried the brass scourers but they are not even close to the solder blob technique for ability to polish the tip. Also the brass usually comes with a lubricant (to keep it shiny) which contaminates the tip and interferes with wetting.

 

[saturation]

Nice, can you share this solder blob technique?

What looks like lubricant in Hakko wool is rosin and it does make it easier to solder and clean. It could be different in other wools used like Weller or clones. The Hakko wool is only $4 and I've only replaced it once in 10 years.

In the end, the sponge is not evil, but its old technology, you can do better if you have newer methods. For least stressful cleaning, use distilled water to insure chlorine and salts don't accelerate tip wear and if the water isn't room temperature already, warm it up to reduce thermal shock.

If you don't solder often the effect of the sponge on tip life may not be as significant compared to using too high heat routinely. Wear rates are increased an added > 30-50% with lead free solder, so temp control is a bigger issue over the sponge, but every little bit helps.

.

Yep, and not just the chance of fracturing but the metal fatigue makes the tip frosty and less able to be wetted, than a good polished tip.

I've been using the "aerated solder blob" technique (which to my knowlege I invented) since the late 1980's when wet sponge was actually considered to be the "proper" way to clean a tip.

I have tried the brass scourers but they are not even close to the solder blob technique for ability to polish the tip. Also the brass usually comes with a lubricant (to keep it shiny) which contaminates the tip and interferes with wetting.

 

[timelessbeing]

Also the brass usually comes with a lubricant (to keep it shiny) which contaminates the tip and interferes with wetting.

I actually find quite the opposite. The brass curls are excellent for cleaning the tip and keeping it wetted. Maybe you got a bad one?

 

[Russ Hensel]

Why worry about the calibration, find the dial setting that works well in each situation and then use it over and over.

 

[timelessbeing]

Because I want the numbers on my dial to reflect actual temperature. The cheap iron I replaced "worked" too but it's not ideal.

 

[Lake9398]

I too have a FX888 and I've found the temperature to be pretty close to what I measured, just a few degrees off but that really won't matter.

 

[timelessbeing]

How did you measure yours, Lake?

 

[saturation]

To optimize life of the tip and your soldered parts, keep tip below 400C; to do this you need to know where 400C truly is on the dial. You can dial down and up as you'd like thereafter, preferably as low from 400C as you can while still getting good joints. Although this URL is a bit self-promoting, the idea is well accepted.

**broken link removed**

If you need to go above 400C and that is known correct temp, its probable the tip is worn [ look inside the tip if it looks good outside] which then conducts heat poorly and should be replaced before it destroys the heater unit or the handset, or its too small for the job and you need a larger tip and pumping up the temp just wears down the small tip unnecessarily.

Why worry about the calibration, find the dial setting that works well in each situation and then use it over and over.