Air compressor for Metcal MX 5251 - Page 1
Forum section: electronics / general

author: mblinov
author_rank: Contributor
timestamp: October 11, 2022, 04:37:35 pm
content: Hi all,I've been looking at upgrading my soldering tools, and rather liked the Metcal MX 5251. Mainly because my current iron is rubbish, but I'd also quite like to have a desoldering gun.The only issue is, the MX 5251 only provides the power, not the vacuum, which must be provided separately.Does anyone have any experience with external vacuum pumps specifically for this purpose that they could recommend? Or would it be better to instead invest into a self-contained desoldering gun + pump alongside the soldering station?

author: mblinov
author_rank: Contributor
timestamp: October 11, 2022, 09:19:22 pm
content: Oh dear, I appear to be an idiot: The Metcal requires an *air compressor*, not a vacuum pump, and uses the "Venturi effect" to generate suction at the nozzle.I have edited the title to reflect this discovery...

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2022, 10:26:38 pm
content: I would not get one of those for home or small lab use, it sounds like something aimed for production line work. Even if the compressor is remote, a venturi vacuum pump is noisy and it will not be very portable. A unit with a self contained motor driven pump is much more practical for most applications.

author: macboy
author_rank: Super Contributor
timestamp: October 13, 2022, 06:24:12 pm
content: I completely diagree with james_s.I have a Metcal MX-DS1 desoldering gun, and it is amazing. The vacuum is powerful, instantaneous (no vacuum motor to spin up), and very quiet. It heats up very quickly (<1 minute), it virtually never clogs, and clears the solder the first time almost every time. I use a "whisper" quiet compressor, which isn't really whisper quiet, but it is not too bad. It's only a few meters away from the bench, but is not more noisy when running than a bench-top vacuum pump for a conventional desoldering gun. But it only runs occasionally, because the air usage for desoldering is quite small. The sound from the gun itself is much less obtrusive than a vacuum pump.An airbrush compressor may be up to the job. They are usually smaller and quieter.

author: mblinov
author_rank: Contributor
timestamp: October 13, 2022, 06:53:09 pm
content: Thanks for your comments guys, if anything I'm more concerned with the myriad of air compressors to chose from, than with the performance of the Metcal equipment itself.Quote from: macboy on October 13, 2022, 06:24:12 pmCould you please share more details about your compressor setup? What pressure do you feed into the gun? I'm also worried about reservoir size.I'm looking at stuff likeBambi PT5(60dB, 4L, max 115 psi), or theSuper Silent 20-A(30dB, 1.8L, max 85 psi), but I really feel out of my depth. The MX-DS1 (which is what the MX-5251 kit comes with) apparently requires 80 psi, but I'm left wondering if the 2L reservoir (on the SS 20-A) will be enough to not trigger the compressor to refill every other THT desolder. I don't want to be waiting around for the thing to fill before taking out another capacitor, or a through-hole PCIe slot with a billion legs.The Bambi is 4L, higher PSI, plus its oil-less which sounds like less hassle (no filters or oil-changes to muck about with), but its a bit louder. But then theres aMakita MAC210Qwhich looks very sturdy (9L, 135psi), and theHyundai HY5508, which is by far the cheapest (presumably because its "direct drive", of which my understanding is that you can't regulate the pressure coming out of the reservoir).There's plenty of videos and forums talking about air compressors in the context of air brushes and nail guns, but unfortunately very little about using them with desoldering guns. SDG Electronics did a video (link below) reviewing the MX-DS1 unit, who uses the SIL-AIR 30/6, but it doesn't look to be very easily available in the UK.P.S. Is there a way to format URL links so that the video doesn't get embedded into the forum post, like below?

author: macboy
author_rank: Super Contributor
timestamp: October 14, 2022, 12:58:10 pm
content: My compressor is a local store brand one which is no longer sold. It is specified around 60 dB noise, has a ~4 gal (~15 l) tank, cuts in at 95 PSI, and out at 125 PSI, and can maintain 2.4 CFM at 90 PSI (much more than needed for this). It is a small compressor, having a carry handle and no wheels. With the MX-DS1 desoldering tool, my compressor will cycle once per approx 20 holes, and it easily keeps up with continuous desoldering.I keep the compressor in my basement, permanently powered and connected to air lines going to my bench and garage. I have a shut-off and regulator/filter at each point of use. I used 1/2-inch PEX plastic water pipe to distribute the air. PEX is relatively safe compared to other plastic pipes like PVC, because while PVC pipe could shatter if it fails, sending shrapnel flying, the PEX would only split open. No shrapnel. At the ends, PEX to NPT (National Pipe Thread) adapters convert to the usual 1/4" NPT fittings typically used for air (at least on this side of the pond). It took some effort to find all the very slow leaks, but once resolved, the compressor now runs a top-up cycle for a few seconds only once per 1 or 2 weeks. For me, the convenience of always having air ready to fill tires, blast dust, or desolder is worth the effort and a little extra wear on the compressor.