Home made Vacuum suction for Weller Desoldering iron

[on4top]

I got really cheap a brand new weller DS50 desoldering iron .

It heats up fine on my WECP-20 .. but i'm missing the Vacuum pump ( costs a fortune )

I found  this on Youtube  : 

He uses a cheap vacuum pump from ebay ..

The only ones i could find on ebay are these :

http://www.benl.ebay.be/itm/191530510757?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649 ( they are from blood pressure medical tools )

Datasheet :  http://www.climbi.ru/thomas/Compressors%20and%20Vacuum%20Pumps/Diaphragm%20Pumps%20&%20Compressors/Diaphragm%20Pump%205010.pdf

http://www.benl.ebay.be/itm/Medizinische-Membranpumpe-Model-MR-12VDC-ELECTRO-A-D-S-L-EAD-Vacuum-Pumps-/191530414959?hash=item2c981a336f:g:imUAAOSwBLlU-12k

Exacly the one of the video i can't find  ..

I think it is thisone  :     http://www.gd-thomas.com/templates/pages/product.aspx?id=2795   seems to be a Wob-l-piston .compressor the on ebay is a real vacuum pump with permanent magnet motor ..

http://www.ebay.de/itm/Thomas-Vakuumpumpe-24V-/222013039797?nma=true&si=FlHW0pbRM%252BxtZPReD7TEkFuCQjg%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

The question is what pomp would be strong enough for this application ?

[SeanB]

Super cheap car tyre inflater can be modified to act as the vacuum pump, simply by using the air inlet as the vacuum port and leaving the outlet to blow into a silencer to damp the otherwise annoying noise.

[DTJ]

The compressor from an old refrigerator can be used as a vacuum pump, couple it with a small vacuum tank and a solenoid to switch the vacuum when needed.

They run very very quietly too compared with normal desoldering vac pumps.

[timofonic]

I want to do this for my future soldering station too! Can it be made steering enough and portable?

[Kjelt]

The compressor from an old refrigerator can be used as a vacuum pump, couple it with a small vacuum tank and a solenoid to switch the vacuum when needed.
They run very very quietly too compared with normal desoldering vac pumps.

+1 when I was a student and didn't have the money I used this setup with a refrigerator pump, it works great but has one drawback: the vacuum pushes the oil out on the other side of the pump.
So I attached a 2meter raiser hose so it could go up.
The better way is too use a 10 liter or something like that vacuum vessel/flask/container (an old butagas flask or something like that will do) and suck it to vacuuum -0.8 bar or something like that than stop the pump shut down with a valve and let the pump go back to normal air again.
If you want even cheaper look at a 12V pump to blow up airbeds, they usually have two openings, one for blowing up and one for sucking the air back out. It does not go to very low vacuum and makes a hell of a noise but with a container as stated above you only have to run it each 5 to 10 minutes depending on the amount of desoldering you do.

[DTJ]

The compressor from an old refrigerator can be used as a vacuum pump, couple it with a small vacuum tank and a solenoid to switch the vacuum when needed.
They run very very quietly too compared with normal desoldering vac pumps.

+1 when I was a student and didn't have the money I used this setup with a refrigerator pump, it works great but has one drawback: the vacuum pushes the oil out on the other side of the pump.

I let mine run for 10 minutes to empty out the refrigerant oil. I just cable tied a small rag over the outlet pipe and slid a small pill bottle over it. It contained all the oil without any issues.

The best thing is the noise - there is none.

With some (all?) fridge compressors they have a PTC  as part of the motor wiring. It prevents the compressor from being started and stopped frequently. If you turn the compressor on then off, you may have to wait two or three minutes before you can turn it on again. It's not a problem if you turn it on and leave it running.

[Kjelt]

The oil was I though necessary for the pump just as a carengine needs oil? 

[DTJ]

The oil was I though necessary for the pump just as a carengine needs oil? 

Yes, I think they do and will eventually fail. Mine has probably 10+ hours on it and is still going strong.

I do not know what the internal construction of the compressors is like - maybe there is a few hundred cc's of oil sitting in the bottom like a sump.

If someone here was a fridge tech or had cut one open maybe they could tell us more.

Heres a view of the insides:



This guy details in the internals - jump to 6:00 for the oil slinger working:

[SeanB]

300-400ml of oil, but it is easy to add more to it, just use ordinary car 0W15 engine oil. In any case if you are recycling a modern compressor you will want to change the oil in it in any case, as the modern units do not use a mineral oil for lubrication, but use a POE oil, which reacts with moisture in the air to form a corrosive mix that quickly destroys the inner components. Used because the modern refrigerants are not compatible with mineral oils, so they use an oil that will pump around the circuit with the refrigerant and which will not make immiscible blobs at the low points. Change it out with mineral oil and it will last a long time. Simply use a cheap air system separator and muffler on the outlet and you can recover the oil or at least see how much you are losing out.

[helius]

In my opinion using a refrigeration pump or other high vacuum pump for desoldering is a waste. Desoldering only requires a slight vacuum, in the range of 600-700 torr. A piston air-conditioner pump operates down to 1 torr, which is a huge mismatch to the requirements.

[Kjelt]

In my experience using a Weller desoldering iron (bent one) with -0.8 bar works waaaaaaay much better than the original Weller soft vacuum pump or even the pressure_to_vacuum_valve some other stations have. I used both and I prefer a high vacuum, it just sucks sooo much better  O0

[DTJ]

I used both and I prefer a high vacuum, it just sucks sooo much better  O0

I reckon high vacuum is best too. I've used a few different vac desoldering stations over the years and the best ones seemed to have a high vacuum that was applied rapidly ( large dV/dt ??) so the joint wasn't cooled and the liquid solder was ripped out quickly.

[Alex Eisenhut]

For sure, you want a quick vacuum. I have a Hakko 707, it has a soft mushy vacuum, it's a big slow pump that takes some time to get up to speed. Worst part is sometimes the diaphragm gets stuck at a weird position where the motor creates a short over-pressure when it starts. Not great. The secret is to pull the trigger firmly and let it suck a few seconds more after sucking the joint, otherwise something like tungsten carbide* builds up inside the heating element.

* Yes, alchemy. It needs drilling out.

[Kjelt]

What I actually also noticed is that with higher vacuum old joints are no problem at all, the more sticky solder will still get sucked up no matter what.
Compared to my present standard Weller desoldering iron, I really do have to apply new solder to a joint or if it is not that bad still add some flux.

If I had to reinvent the standard Weller desoldering iron I would place a small vacuum valve on the iron just after the filter and apply vacuum first for a few seconds than activate the valve.
If you would like to try this yourself, take your left hand and tighten the flextube of the iron , apply the vacuuum press the iron at the pad release the flextube and woooops gone it is, much faster than with the standard behaviour where the vacuum first has to vacuum out the whole hose.