I'd like to build a desoldering station. Conventionally this is done with a soldering iron and a vacuum source. In the best units the tip of the iron is hollow and the vacuum draws through it. But I don't want to purchase a vacuum pump for the same reason that I don't want to purchase a commercial soldering station: cost. I have a compressor. Since there are COTS desoldering stations that work from a compressed air supply it's possible, using the Venturi effect, I believe. Are there any on-line tutorials for creating a vacuum from an air source?
I wouldn't think they could even sell you the housing and handle for that.
Speak "I went to open the refrigerator this morning and the handle fell off the door...When I grab my briefcase the handle tore loose...Now I'm afraid to go take a leak."
||I'd like to build a desoldering station. Conventionally this is done with a ||soldering iron and a vacuum source. In the best units the tip of the iron ||is hollow and the vacuum draws through it. But I don't want to purchase a ||vacuum pump for the same reason that I don't want to purchase a commercial ||soldering station: cost. I have a compressor. Since there are COTS ||desoldering stations that work from a compressed air supply it's possible, ||using the Venturi effect, I believe. Are there any on-line tutorials for ||creating a vacuum from an air source?
You can buy a air-driven venturi vac pump from Harbor Freight for $10 on sale. It works fine, but it's noisy. Texas Parts Guy
Is there some reason why you don't just buy a Solder Sucker? This is a hand held plastic device which you c*ck. You then apply soldering iron, poke the teflon tip of the solder sucker into the melt and press the trigger. It produces a short, sharp suction that is very effective.
Looks like the Single Stage AV Series Pump is what you're looking for. A friend of mine purchased the AVR093H (High vacuum level) while attending the Bell Composite school, and said it works like a champ. They sell for $21, and air consumption rates are about a quarter of the Harbor Freight unit. They also make a Low and Medium Vacuum Level version.
So -- make your own. It's not rocket science. Do you have a lathe? The basics are:
+-----------------------------------------------+ | | |_______________ ________________| \ / Air \____________/ Air In Out ____________ / || \ _______________/ || \________________ | / \ | | | | | +--------------------- ----------------------+ Vacuum port
I'll leave it to you to select the proper threads for the various fittings, and the size to suit. I would probably start with a 1" diameter piece of bar stock, and use a pretty small pipe thread for the vacuum port. If you need a larger port, increase the size of the stock to make sufficient room for the threads.
It would benefit from a smoother curve at the start of the restriction and at the exit from it, but this should be sufficient to give you some vacuum. It will be noisy, so run the air-out away from you with another hose.
The basic principle is air in with large diameter, reduced diameter where the vacuum port is, and then back to large diameter.
Material ideally should be bronze or stainless steel, but brass or aluminum would work for a shorter time, or even plain steel, as long as your air supply is nicely dried.
For a desoldering iron application, I think you'll end up wanting something more effective than a Harbor Freight generator (not that I've tried them, but I've used numerous different brands of commercial desoldering stations).
The Air-Vac desoldering iron venturi generator is very effective for two reasons.. it's designed very well (and provides instantaneous vacuum at the tip), and because it's located on the handpiece (being closer to the tip). The older irons are often on eBay and sometimes don't even get any bids. These desoldering tools are the style with the glass collection chamber above/alongside the heater-tip assy.
Many other systems use an electric pump with a reciprocating diaphram and rubber-like reed valves. The glass collection chamber is inside the handpiece (which is more compact), and the handpiece has a long piece of flexible tubing between the handpiece and pump. This introduces a little delay in the vacuum, but they work fairly well. The electric pump is typically a 12V, 1 to 2 amp PM DC motor (about 2" x 3") that's run intermittently with 24V. The pump diaphram is about 1-1/4" diameter with about a 1/8" stroke.
Nearly all of the heater-tip assemblies of the more recent models are low voltage heaters.. typically 24V. For a scratch-built improvised design, you wouldn't need closed loop temperature control, but a temperature adjustment will be a good idea (triac or variac), so you can turn the temp down for more delicate, easily damaged circuit board work. For circuit board work, you'll definitely want the tip to be earth grounded. The Pace heaters are short, and aren't as versatile as the longer heaters are.
The glass vial is a nice sight glass feature, but a metal tubing chamber works just as well. Silicone rubber seals are usually used at the ends of the chamber.
Another feature you might want to include would be the versatility to enable you to use hot air coming out of the tip for surface mount components or some other non-contact application (such as heat shrink tubing). You'll probably want to implement a needle valve similar to a CFH gage, since the air flow needs to be low to maintain heat.
Fitting numerous features into a handpiece are a bit complicated, but you can use a foot switch to energize the solenoid for the air source (that way, the iron heat is replenished/saturated when the vacuum is off), or on/off for an electric pump.
For solder/flux vapor filters you can use a variety of materials, but you should avoid steel wool if you're doing circuit board repairs.. a single strand of wool can be hard to find if the circuit doesn't work (I found that out many years ago). I've used roll-type bandage gauze for filters.. it's a convenient size to roll up into the pellet shape.
Good ideas from "Wild Bill." I'd add the following -- I'm thinking about doing this myself, perhaps this winter.
I think I'd want a vacuum reservoir. I don't think it would take much, maybe an old 14 -oz propane cylinder or two, or perhaps a piece of 4" ABS pipe with caps. Scrounge or contrive a simple vacuum-actuated switch: maybe a diaphragm and a microswitch. Find some cheap surplus solenoid valves. They show up at my surplus store every now and then for a couple of bucks each. I'd valve the air to the venturi, but the line from vacuum tank to venturi would also have to be valved. Then a third valve would pulse vacuum to the sucker with a finger-operated or foot-operated switch. The "sucker" might just be a bit of small-diameter stainless or teflon tubing. I think I'd keep the sucking and heating functions separate: melt the solder with a temperature-controlled soldering station I already have.
I've found that fluxed copper braid (Solda-Wick) works pretty well with surfacemount stuff, but sucking out the bulk of the solder first would speed that up some.
BTW, that HF vacuum venturi is dirt simple (I've taken one apart) , but for $9.95 it's hardly worth bothering to make one. They claim a pretty good vacuum, something like 27 or 28". I don't have a gage suitable for testing to verify or refute that claim. It is definitely noisy, but so are inexpensive electric diaphragm pumps that produce significantly less vacuum. With a good vacuum you'll have more delta P (maybe 13 PSI) so I think we'll get more volume and velocity thru a given vacuum nozzle, hence more vigorous soldersucking.
The problems with the pushbutton soldersuckers like Solda-pult are: the nozzles are kinda bulky, they "kick" when released which sometimes jerks the nozzle away from the site to be sucked, , and you only get a pulse of vacuum that doesn't always do the job.
Keep us (or at least me) posted >For a desoldering iron application, I think you'll end up wanting something
I really like the idea of a vacuum reservoir because it can also serve as a "sucked solder catcher". Using something like an empty propane cylender would probably take at least a half a lifetime to fill up (and I hope I don't have that much longer to go ;->).
The solder solidifies rather fast when you remove the heat source - the solder catch bottle or chamber needs to be on (or inside) the desoldering sucker iron handle itself, or within about 6" of the nozzle. Molten solder won't stay molten for travel through 3' of hose and a solenoid valve to get to the propane cylinder vacuum reservoir.
If you try that, you'll only end up with a hose plugged with a big gob of teardrop shaped solder globs....
Yep, there are several other fine points, or details to designing such a system from scratch. If the solder cools too quickly (from the heater temp being too low, low thermal mass, or drawing too much air thru the heater), the solder will solidify in the passage and cause blockages. Clearing blockages is more troublesome than using solder wick.
The hot solder should be captured as soon after the heater as possible. A solder trap in the collector chamber will prevent the solder from clogging the filter. The trap can be a wavy aluminum strip or a spring coil, so that the molten solder hits it and solidifies on it instead of hitting the filter and clogging it. The filter captures the finer solder and flux vapors, preventing them from reaching the tubing and pump.
The most economical tips are the 1" long 1/8" diameter plated copper tips (such as Plato 20-0110). The heater assembly could be adapted to hold these plain tips with a stainless steel set screw. Tips that are threaded or plated steel will be much more expensive, and really aren't more cost effective.
I've used solder irons with solder suckers and lots of squeeze bulb-type desoldering irons, but there's nothing easier to use than a properly operating desoldering station. It's good to have wick handy sometimes, and it works even better when you put a little (just a little) liquid rosin flux on it.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.