Electric vaccum solder sucker?

Tonyr1084

Joined Sep 24, 2015
6,462
Anyone have an idea of how powerful a pump you would need?
Using a reservoir to accumulate total vacuum you can use just about any pump. Since I've never built one I really couldn't tell you how to go about it. However, modern cars have air pumps that pump air into the exhaust stream. I'm SURE they have an inlet side. However, I don't know how much amperage they would draw. Smaller cars should have smaller pumps. You'd have to do some modification work in order to get a usable device for the purpose, and it's also possible the pump would move enough volume so you wouldn't need a tank. Still, the idea of ramping up a vacuum versus the ready volume (or lack thereof) controlled through a valve should be the best solution, allowing you to heat the joint then to rapidly apply a suction, same as a spring loaded sucker.
 

jbeng

Joined Sep 10, 2006
82
I realize you're wanting to do all this yourself, but why re-invent the wheel?
Over the years, I've used the Pace MBT series systems and they work really well, especially if you keep them clean. "Pre-owned" units can be had rather cheaply these days on eBay & they have the pump and tip temperature controls built right in. Most even have multiple channels, allowing a vac tip and a solder pencil to be connected to the same power unit.
 

Tonyr1084

Joined Sep 24, 2015
6,462
The only issue I see is you might want it running most of the time but I guess you could have a foot switch to turn it on and off.
Problem with having it running all the time (during solder removal) is that the movement of air will strip away the heat and not allow the solder to come to molten temperatures. The sudden application of vacuum is typically what is needed. Hence the reason for a vacuum reservoir and a solenoid valve. Besides - having a reservoir tends to preclude sucking bits of solder into the pump.

In fact, I use a small tank and vacuum pump to change the oil in my lawn mower, edger and snow blower. Rather than lifting the machine up on a table to open a drain valve, sucking it out through the filler tube works pretty sweet. But in that case I don't need a sudden vacuum. A steady stream works well. Well, ALMOST "well". One problem I've encountered is that the pump can move air faster than the oil coming up the tube. When the machine empties and a sudden source of fresh air is available the sudden inrush of air tends to splash the oil into the pickup tube and oil down my pump. But oil is not harmful to a pump. Not like bits of solder would be.
 

shortbus

Joined Sep 30, 2009
8,971
In fact, I use a small tank and vacuum pump to change the oil in my lawn mower, edger and snow blower.
Only problem with that is unless the motor has an oil filter, you have to change oil when it's hot and soon after shutting it off. Or the bad stuff is just sitting in the nooks and crannies of the crankcase waiting to mix in with the fresh oil. :)
 

MisterBill2

Joined Jan 23, 2018
9,877
I think that the required vacuum is a lot more than you get from even a great shop vac.And the big thing is the velocity of the air carrying the solder away. The higher velocity demands greater force, in this case that means a greater vacuum.
 

Tonyr1084

Joined Sep 24, 2015
6,462
Only problem with that is unless the motor has an oil filter, you have to change oil when it's hot and soon after shutting it off. Or the bad stuff is just sitting in the nooks and crannies of the crankcase waiting to mix in with the fresh oil. :)
The same is true putting the machine up on the workbench and draining the oil out the bottom of the machine. And I've never been a big fan of changing hot oil. But even then the hot oil still hangs around.

With the fresh oil ever so slightly diluted with the older dirty stuff - the machines still seem to last a significant length of time. But if I really wanted to get rid of as much dirt and old oil as possible then I'd use some really cheap oil to be diluted with the old stuff, then change the oil again after just one running of the machine. In fact, years ago I did just that with my car. Was planning on selling it so I changed the oil and put cheap stuff in it and ran it for a day or two, then changed the oil again. Boy did things look good. The buyer (my older brother) thought I took excellent care of the car. Boy was THAT far from truth. Back when I was young I had no idea changing motor oil in a car was so important.

Back on topic now - and this has been said numerous times - you need a sudden strong pull of vacuum. Running a continuous draw of air will keep the tip cold and likely not let the solder melt. You need still air, plenty of heat and a sudden vacuum to draw out the molten solder. Then what little remains just needs to be fatigued from the sides and the device will come right out.
 

MisterBill2

Joined Jan 23, 2018
9,877
Both Tony and Short are right about stuff getting into the compressor. Thus the simple solution is to have an accumulator tank and a filter between the pump and the tank. The pump runs and pulls an adequate vacuum in the tank, and then switches off. Then the unsoldering begins, using a fast acting valve to switch on suction as needed. Then when the vacuum reaches the smaller setpoint the pump runs again while the process waits a few moments. Then the cycle can repeat. The tank need lot be large, a gallon size is the largest that might work. So the pump-down will never take long.
 

Tonyr1084

Joined Sep 24, 2015
6,462
The tank need lot be large, a gallon size is the largest that might work. So the pump-down will never take long.
The tank I use is a quart. For changing oil it's small and repetitive but it's also quick pulling a vacuum using a small pump. Maybe later today I'll go snap a few pictures of the pumps I happen to have. They're not easily found and they come from two different industries: One is from a glass blowing shop and the other is from an old "Sun Engine Analyzer". They have rubber diaphragms and flapper valves and they run on 110 VAC. I've connected quick-disconnect hose connections so I can rapidly repurpose them for other tasks as they might arise. Also, the tank needs to be rigid enough to not cave in when you pull a vacuum. Otherwise your efforts will be disappointing - to say the least.

I HAVE used glass bottles, but with that you run the risk of dropping them. Oops. Then you have a dangerous mess to clean up. (oil speaking)
 

shortbus

Joined Sep 30, 2009
8,971
The same is true putting the machine up on the workbench and draining the oil out the bottom of the machine.
Just an answer to what you said. The crankcase in most small engines isn't perfectly flat. It is sloped or dished to the drain opening, so the particles in the oil will tend to drain out when the plug is pulled. Not so when pulling it out of the filler.
 

MrSoftware

Joined Oct 29, 2013
2,015
The powered units like the one I linked do not have vacuum reservoir tanks. They have a little pump that turns on the instant you pull the trigger, probably similar in size to the pump I linked. One key is the solder suction tube in the gun gets hot most of the way up, and that helps prevent the solder from cooling and clogging the tube. It still happens, but not very often if you let get all the way hot before using it, and use the cleaning ram-rod every so often. To stop solder from getting into the pump, the gun has a cone shaped spring to catch the solder, plus a thick felt-like filter in front of the vacuum line to catch anything that gets by the spring.
 

Tonyr1084

Joined Sep 24, 2015
6,462
Not so when pulling it out of the filler.
I always put the machine on a block that angles the oil toward the bottom of the fill tube. Keep in mind, i'm not talking about a 4, 6 or 8 cylinder engine, these are the simple small one cylinder types with the flat bottoms. I know they're flat because since I was a kid I've been tearing them apart. Some have pumps in them, most rely on the splash oil system. When I vacuum out the oil the machine is tipped so that the low spot is directly beneath the filler.

Anyway, enough of the Briggs & Scrapiron motors and oil.

Nice thing about this website is I can learn so much from others experiences and knowledge. I suppose a tiny pump can pull enough sudden vacuum to desolder a joint.
 
I have a motor driven de-soldering tool. The vacuum pump motor is in the handle.
View attachment 170329
Denon 7000. I don't know if it is the same as atferrari above.
This has given me great service for many years. And well it should. It was quite a few hundred dollars. In fact, Googling it has quite scary prices!
Price: £1,067.77 in one place, € 599.76 another

It came with a range of heater/barrel sizes and replacement filters. In an attempt to clean the filter cylinders, I dropped them into the water based PCB cleaner and the plastic cracked. So it does not like getting wet.

A good de-soldering tool is a great thing to have and they are a lot cheaper now. Get one that has an actual vacuum pump of some sort, not just a spring tool. That helps avoiding the recoil damaging the board.
 
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