New fnirsi sag-55 hot air gun - Page 1
Forum section: electronics / testgear

author: geonicz
author_rank: Contributor
timestamp: August 14, 2025, 04:20:16 pm
content: Going to review this unit in a couple of days. Received it a month ago from their official site and regret.Horrible temperature error, horrible support but I still hope to get my money back or at least make it work as a hairdrierIn a few days I'm going to disassemble it and show everything inside.Anyway, another unit from another company is in transit.To be continued...

author: csuhi17
author_rank: Frequent Contributor
timestamp: August 14, 2025, 05:28:22 pm
content: My statement may seem a bit rubbish, but I hope that only your copy was bad, and you manage to get a refund.A few days and the same Frinsi product I ordered will arrive at my door.I haven't found another cheap, single-use warmer with three memory slots.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: August 14, 2025, 05:43:49 pm
content: Quote from: csuhi17 on August 14, 2025, 05:28:22 pmThere is also this one..https://www.eevblog.com/forum/reviews/alientek-h550-programable-hot-air-gun/msg5906546/#msg5906546

author: csuhi17
author_rank: Frequent Contributor
timestamp: August 14, 2025, 07:20:10 pm
content: Quote from: DaneLaw on August 14, 2025, 05:43:49 pmBoth are 550W, the Alientek H550 is a bit more expensive.I might order some and keep the better one.It seems like I'd better look around at Alientek first if I need anything.Thanks.

author: geonicz
author_rank: Contributor
timestamp: August 15, 2025, 03:47:27 am
content: So do I: I've got several devices from Alientek with practically no complains.But fnirsi... The only thing they make is garbage in shiny boxes...I was unlucky to buy sag-55 just a couple of days before alientek released their hot air gun. Yep, I have to agree, I bought it because of 3 memories and portability(which is bad actually).

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 15, 2025, 04:38:41 am
content: They make a lot of garbage, it's true. However, some of the toys they make are okay. They're still toys, but if you keep your expectations low, they can be fun.

author: shabaz
author_rank: Frequent Contributor
timestamp: August 15, 2025, 05:19:48 am
content: This one actually looks like an acceptable product for the price.An honest reviewhereby someone I trust.

author: csuhi17
author_rank: Frequent Contributor
timestamp: August 15, 2025, 06:19:03 am
content: "I can't comment on reliability (it's only been out of the box for couple of hours) but the first impressions of performance are very good."Because of this I can't take it that seriously, this is just an unboxing, where it was tested with a SOT23 transistor. My older Yihua 8509 mini device can also solder it.I can only take the longer comments like "I've been using it for weeks and the price-performance ratio is good but it's not the best for larger ICs, don't even try GPU ICs with it, etc." as credible.

author: shabaz
author_rank: Frequent Contributor
timestamp: August 15, 2025, 09:48:04 am
content: He wrote it when he received it, armchair critic. It's a new product, I can't see how you can expect much more?. And it's a bit more detail than the OP's "horrible support" or "horrible temperature error", the latter which we can already see wasn't the case for the reviewer. Same with OP's comment on another thread about a FNIRSI power supply where others have created reviews that don't align with his experience at all.You yourself are trailblazing by purchasing this product so soon after launch, before there are many reviews written. You could have chosen to wait. I hope you write a comprehensive review after some months of trying it?I'm sure people will report over time if there are issues.

author: geonicz
author_rank: Contributor
timestamp: August 15, 2025, 01:12:44 pm
content: I'm going to compare these two. Sorry for yihua8858. It looks ugly and used too much. Tape around the body doesn't make it shine, but anyway, it works and I'll have to use it some time. And there're some things that make it a much better choice. F.ex. temperature accuracy, air flow, power, handle weight and ergonomics, and price for the last.

author: geonicz
author_rank: Contributor
timestamp: August 24, 2025, 05:26:35 am
content: I've already received another hot air gun. Yihua 8858 IV. Looks good enough. Cheaper than sag-55 twice, works(at least:), works better than sag-55. Quiet in comparison.I already got 3 hot air guns, one more on its way to me. Thanks to fnirsi(hate them!) for this hot air gun's garden.

author: BillyO
author_rank: Super Contributor
timestamp: August 29, 2025, 08:19:17 pm
content: Quote from: geonicz on August 14, 2025, 04:20:16 pmJust received mine. Temperature error: set to 300C - measures 298.3C.Does not seem like such a Horrible temperature error to me.

author: geonicz
author_rank: Contributor
timestamp: August 30, 2025, 08:41:03 am
content: Interesting. How do you measure the temperature?And one more important question: do you have temperature fluctuations? As I see you put sensor on it and hold it still(I suppose). Do you have a drift of 40-60*C in a minute or so?It's something really strange and what I can't explain right now.At this time I've got 4 units from two different companies of 3 different models. 2 working fine, 2 faulty fnirsi.And this is really strange, as I've got problems with fnirsi only.They managed to send me a replacement(2 months passed, >20 messages, fed up). With a bit less error, but still it's there. Less horrible, but still there and still horribleI've got 4 guns to compare, a bunch of thermocouples, thermal sensors, noise measurement devices but now I'm so fed up with this crap that I'm not sure I'll manage to do this work now ( I'd rather throw it into a wastebin than even hear about it.I haven't decided what to do, but I'd never recommend anyone this company. Heap of shit.

author: csuhi17
author_rank: Frequent Contributor
timestamp: August 30, 2025, 11:32:35 am
content: I got the Alientek but with a small error, it doesn't want to start heating and it stops working.The seller has already sent the replacement part.I tested the Fnirsi with my Uni-t thermometer, type K and the small end, 1 cm from the end and without a nozzle.At 300 celsius it ran up fast to 277 degrees when starting, then dropped back to 220 degrees. It also held with a +- 10 degree difference. At a fan setting of 10.When I set the fan to 20, I didn't experience a significant change in the temperature, it went up to 225 on average and kept the +- 10 degree difference.When set to 450 degrees with a 20 fan, it went up to 320 degrees, the difference was also +- 10 degrees.When I turned the fan down to 10, the temperature went up to 360 degrees, but here the difference increased to +- 15 degrees.It keeps the temperature well, if someone has a bigger difference than this, there is a high chance that there may be a bug in it.When soldering PCBs, the temperatures are of course different, higher, just like with a larger surface area thermometer head!I've soldered a few things with it and it works well.It is louder than the Alientek, but I think it is tolerable.The grid at the end is much thicker on the Fnrisi, meaning the holes are smaller. It is about half the size of the Alientek.I think it can be used well with a nozzle larger than 6mm, but it does not pump enough air for the smaller one, I think it is worse to use with the smaller nozzle, at least compared to the yihua 8509.This is my 4th usable Fnirsi product and only 9 have ended up in the trash. The ratio has improved.

author: BillyO
author_rank: Super Contributor
timestamp: August 30, 2025, 02:04:45 pm
content: Quote from: geonicz on August 30, 2025, 08:41:03 amYou can see in the picture how I measured the temperature. Placed the unit as shown in the stand, put the PT100 probe on the opening as shown, tuned it on and waited until the temperature stabilized. Yes there are temperature fluctuations. It initially went as high as 303, came back down to 296 then went back up to 298 and varies maybe a degree either side of that. No 40-60 degree drift.Quote from: csuhi17 on August 30, 2025, 11:32:35 amYou need to measure the temperature as close the unit as possible. It would be best to measure it inside. Not 1 or 2 cm away. It cannot determine the temperature 1 or 2 cm away, it can only measure and respond to the temperature internally. When the air exits, there will be turbulence and mixing with the ambient air, which of course is a lot cooler. This will cause fluctuations and teh temperature will be lower than internally.To both of you...You do realize that it can be adjusted, don't you? I did not have to adjust mine as it seems to work just fine out of the box. Also, what did you do to eliminate air currents and turbulence? How did you control the experiment? What was the ambient air temperature?

author: BillyO
author_rank: Super Contributor
timestamp: August 30, 2025, 02:40:02 pm
content: Here I'm using a different meter and using a thermocouple rather than the platinum thermistor. I take measurements at 0 cm, and approximately 1 cm, 2 cm, 4 cm and 6 cm.

author: csuhi17
author_rank: Frequent Contributor
timestamp: August 30, 2025, 04:04:41 pm
content: The ambient temperature was 27.9-29.1 celsius whitout wind.I know that this was not a 100% controlled test, here I was only interested in whether if I "use" it, there is the 60 degree fluctuation that Geonicz wrote.I know that i can change the calibration.I tested is for 1h and it was fully stabil.By the way, the Alientek description says a few words about how to measure and what to look at and how to "calibrate?".There they put a larger diameter nozzle on it, on the side of which the probe is attached with Kapton tape, not in front of it in the airspace.

author: BillyO
author_rank: Super Contributor
timestamp: August 30, 2025, 04:20:47 pm
content: Like so?That should probably work too. It might be a tad cooler than the actual air and that hose clamp will add thermal mass and make it more stable, which I guess is a good thing for calibration purposes.

author: Fraser
author_rank: Super Contributor
timestamp: August 30, 2025, 05:15:11 pm
content: I also bought a SAG-55 as it was on a special offer when first released. For reasons unknown it took a long time to ship and I suspected some ‘teething troubles’ or production delays. After chasing FNISI for an update on dispatch, I was told that the unit had proved more popular than expected so production could not keep up with demand.My SAG-55 eventually arrived and it is performing well, given its fan size imposed limitations. My main hot air station is a JBC and that would be my choice for larger BGA IC’s, but the SAG-55 holds a decent temperature at its output (+/-10C) and desolders SMT components without drama. As has already been said by others I would not use the SAG-55 with small nozzles as the fan is not suited to pushing against such an air flow restriction. When looking at these hot air stations we need to consider the physics of the situation. A heater is pretty much a heater in terms of what it does, but the fan or pump assembly can vary greatly in hot air stations. In my experience I do not require a hurricane force air speed at the hot air stations nozzle, yet some stations use huge powerful blowers that promise such air speeds. My professional JBC hot air station uses a sensible range of air speeds and is most certainly not blasting components into space during reworkIf a PCB appears to need huge hot air volume then maybe a pre-heater is justified and that is the normal thought process for challenging PCB’s like those found in PC’s etc with large copper pours in the layers. The fans located in the handle of these cheap hot air stations are pretty low performance compared to expensive stations that use large snail shell fans, air turbines or diaphragm pumps. To create high air flow they either need to be large or very efficient small fan designs run at high speeds. I hoped that the FNIRSI SAG-55 would be like the technology used in Dyson vacuum cleaners (high speeds, high performance) but alas that is too much to expect for £50 including delivery to the UK from ChinaWe have to be realistic here at the price point. Yes the SAG-55 does work as a light duty hot air station and can desolder many sizes of SMT component, if you take your time, but it is nowhere near as good as my JBC and that is absolutely no surprise to me. £50 Vs >£1K …. Not really a fair comparison. Use common sense when selecting a hot air station. Just because it looks ‘sexy’ does not mean that it can do the job you expect of it and do be fair to the the hot air gun, if the PCB is basically acting like a giant heat sink, use a pre-heater !Having seen mention of GPU rework…. I would not use hot air for that anyway. I bought a Jovy LWIR rework station for those challenging situations involving very large BGA IC rework. As the old saying goes… use the correct tool for the job. You also tend to get what you pay for with tools and equipment. Buy cheap, get cheap. FNIRSI tries to produce products for the budget end of the market but sadly their products appear to be a sheep in wolf’s clothing and can have ‘issues’. When All is said and done, they are cheap kit and the issues with their products are well documented on this forum. The SAG-55 is an OK mini hot air station but it will not set the World on fire !I am just waiting for FNIRSI and other budget equipment manufacturers to claim amazing performance thanks to some new deep learning AI engine that makes up for all the other shortcomings in the piece of budget equipmentIf someone wants a decent hot air station, I would steer them away from units with a small fan in the handle and recommend one of the larger hot air stations that have a decent sized blower unit in the main station connected to the handpiece via hose. There are several excellent hot air stations that cost less than £300 that can cope with most hot air rework tasks.