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[Articles Home]  [Add Article]  

$30 DIY Desoldering Station

Ron Wagner (WD8SBB) on September 28, 2012
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THE PROBLEM

Plate through hole PCB rework really benefit from a good vacuum desoldering rework station, and I really wanted one. Unfortunately the price tags of such stations kept me “just looking”. I ran into a Hakko 808 “poor mans” rework kit at a hamfest, but I was also put off by the almost $200 price tag. Eventually I ran into a desoldering iron with a built in Soldapullt type pump (fig1) at Midwest Surplus Electronic (www.midwestelectronics.net) for $13. I figured, for the price, I couldn’t go wrong.

I used the unit heavily for about 18 months when it started to have performance problems. I did a normal cleaning and oiling, but its performance did not return. I figured the o-ring had worn. I opened the unit and disassembled the piston. Upon inspection, I found that it was not the o-ring, but that the shoulder washers had fractured. One had a “hair line” fracture while the other a major crack (fig2). Apparently the continual “hammering” of the washers during usage had taken its toll.

I purchase a second unit to use while looking for parts to fix my original unit. I found parts in the plumbing department of my local hardware store. After several attempts, I had it working, but just not as good as it had worked originally. I consulted my coworkers for ideas, but after several attempts, was still was not getting the performance I wanted.

I decided to visit with my good ham buddy Mark KD8FOD for an engineering consultation. He also happens to have a small metal lathe, which might be able to make me custom parts. While discussing the situation, we looked up the Hakko 808 on the web. We ran Google searches on various related key words looking for cheap desoldering solutions. Mark told me he would be happy to turn me metal shoulder washers to replace the original fractured plastic ones. He also mentioned that he “knew” I could engineer something at least as good as the Hakko for less than ½ the cost. Mark had thrown down the gauntlet.

I went home and thought about the problem. I looked at a lot of web pages but found only one particularly interesting design at www.teaser.fr/~amajorel/desolder. I didn’t have access to a refrigerator pump, nor did I have room for a unit like that at my bench. Still that general design was really interesting. About a week later while using a foot pump to inflate a wheelbarrow tire in the garden shed, it hit me. I wondered if I could convert the foot pump into some type of a vacuum pump.

The next day, I took the foot pump from the garden shed and disassembled it. A few hours later, I had rearranged the unit into a reasonable vacuum pump. After a couple temporary configuration and tests, I had what appeared to be a working vacuum desoldering station. After a few more tweaks and corrections, I had a very usable vacuum desoldering station.

With my final unit (fig 4), I’ve taken off various types of ICs on various types of PCBs, including .07 DIP ICs in plate through holes. I have used my desoldering station to repair equipment and recover parts and ICs for reuse. Although my desolder station is not for every need, I now seldom use any other desoldering technique for through hole components on PCBs.

CONSTRUCTION

Remember to use all appropriate safety equipment with any power or hand tool use. Observe all safety instruction that come with the tools. If you are not familiar with appropriate use of hand and power tools, do not use them until you are.

Pump disassembly and modifications. Disconnect the pump gauge and hose by unscrewing them from the pump body. A small rubber check valve between the pump and the gauge may fall out, that is okay. If the rubber check valve doesn’t fall out don’t worry, we will remove it later.

Unscrew the piston rod nut that holds the rod to the frame of the foot pump. This will allow the pump frame to spring open. The piston housing end-cap is typically friction fit or crimped onto the piston housing. Use the side of a flat blade pry bar to hammer the end-cap off. If this is not working, you can use a hack saw or Dremel tool to carefully cut the end-cap’s lip. Be careful to only cut the end-cap lip, do not cut into the piston housing.

After you have the end-cap open, you can take out the piston. Be careful, as the piston will have grease and oil that will get on everything. Use paper towels to clean everything up. Take the o-ring off of the piston and set it aside. Take the piston, and put a locking jaws pliers on the rod close to the piston. Now carefully spin the piston so as to free the rod. The rod will not come out, but will spin. Remove the pliers. Next position the rod so that you are looking at the top of the piston. Now carefully drill a small hole large enough for a punch in the center of the piston. You will drill until you hit the metal rod. At this point stop. Put the piston on a vice so that the rod is down, and the piston lays flat on the vice’s jaws. The vice should be loose, and not “clamped down” on the piston or rod. Now take a punch (I actually used a nail) and drive the rod out of the piston. This should be fairly easy since you loosened up the rod earlier

Take the piston, and find a drill that fits into the hole where the rod was. The drill should ideally be just slightly smaller than the hole. Now drill through the piston with this drill. Next see if the piston rod will fit into the hole from the top of the piston, it should not. This will allow us to refit the rod into the piston while hot and have the plastic melt and reset against the piston rod. Once reset, the rod will be held in place like it was originally, only from the opposite side.

With the piston rod and piston ready, it’s time to reinstall the rod. While holding the threaded end of the rod, use a butane lighter, or candle (you can use a torch, but it is overkill) to heat the far end of the piston rod. Since the rod is steel, it will take a long time to heat. At some point, you should begin feeling the heat on the thread end of the rod. This is the point when the rod is hot enough. Take the rod and carefully push it into the piston hole from the top of the piston. Push it in about ½ to ¾ of an inch while making sure it is square. It should be in far enough so that the “barbs” that were used to hold the rod in originally are again inside enough to hold the rod in the piston. Let the entire assemble cool, being careful that the rod and piston are square.

Take the piston housing part of the pump and verify that the rubber check valve is removed from the gauge hole. If not a small piece of wire pushed from the inside of the housing will pop it out the threaded hole. Make the threaded check valve hole larger inside so that it does not restrict the flow of air. Do this by finding a drill that “just fits” into the threaded side. Drill out the hole and then clean up the entire unit so that all grease and chips are removed. This is very important because any chips left will destroy the o-ring in short order.

Reinstall the o-ring on the piston. Apply either a small amount of oil or petroleum jelly to the o-ring and reassemble the pump. The piston should move up the housing easily if enough lubricant was applied. Do not permanently attach the end-cap at this point. Make sure the system is working by putting you finger over the threaded hole on the far end and drawing the piston out of the housing. There should be reasonable suction. If not look for issues like drilling chips, inadequate lubrication etc. Once you feel the unit is working, assemble the end-cap. If you disassembled by pounding the end-cap off, then you should be able to pound it back on. If you chose to split the end-cap’s crimped band, you will need to use a large hose clamp to hold the end-cap on. Once the end-cap is reinstalled, assemble the rest of the foot pump by putting the piston rod back into the frame and putting the nut back on the end of the rod.

You should now be able to use your foot to compress the pump, then let it go and hear the air suction in. You should be able to put your finger on the air inlet, and the pump should move very slowly to the open position. The slower the pump opens, the better vacuum the pump is creating.

Next put a hose about 6 ft long on the front of the vacuum pump. I used 3/8 inch ID vinyl tubing because it is stiff enough not to crimp yet flexible enough for the job. The pump’s old gauge nipple should allow you to push the tubing over it. It will be difficult, so it is best if the tubing and the pump are warm. An ideal way is to set them in a closed car in the sun. The tubing will stretch easily when hot and then it will cool and “stick” to the nipple on the pump. Since the pumps are generic, you might need a hose clamp, or different ID hose for your pump.

Test the vacuum again from the end of the hose. Like before, the pump should open slowly and you should not hear leaks. If there are leaks, you need to find and correct them.

Desolder pencil preparation: Disassemble the desoldering pencil. Remove the piston by unscrewing the nut and removing the shoulder washers and o-ring. Slide the piston rod out of the black plastic end-cap. The release button and spring will fall out at this point.

Take the brass tube and with a file, put 4 notches on the end of the tube. These notches are used to “dig” at the edge of the plastic end-cap. Push the brass tube into the end-cap while twisting. This will be a difficult task, but will produce a very tight fit that will not need additional sealing. Expect to take 30 minutes or more to accomplish this task. If you really do not want to do it this way, you can drill the end-cap out and then use silicone caulk to fill in the entire length of the tube inside the end-cap.

With the brass tube through the end-cap, you need to solder a shield on the front of the tube. This shield prevents solder from being sucked back into the tubing going to the pump. This is a very important item; my first attempt at this device had solder in the plastic tubing that was very difficult to remove. I had taken a look at “free patents online” to get ideas on how to address this issue. My final solution is nothing spectacular, but it works. I also left the original spring in place so as to catch “side shot” solder, and then placed a small shield over the front of the tube (fig 3). Remember while making the shield that you need to allow plenty of area for the air to flow. You do not want the air to be restricted, or your desoldering vacuum will suffer.

Connect the hose to the brass tubing, using silicone caulk as filler. Caulk up about ¾ inch of the brass tube and install the tubing on it. Allow this to dry for at least 48 hours before moving to form a good seal. Assemble the desoldering iron and vacuum line. Now take silicone caulk and fill in under the hose on the desolder pencil toward the end of the housing. This will allow you to later wrap the hose so that it does not move relative to the brass tube. Allow this to dry for 48 hours as well.

You need to then carefully peel the caulking off of the tubing of the desolder iron housing. This is so that you can empty the solder chaff periodically. After you have completed this, secure the hose in some manor. I used Velcro cable wrap to hold the hose (fig 4).

Once all the silicone is cured, you can try the system cold. You should be able to push the pump down with your foot. You might hear a little air at the desolder tip. When you let go of the foot pump, you should hear a long steady suction at the tip. You should also be able to cover the tip of the solder pencil and the foot pump should stay down or slowly come up. If you have leaks, you need to address at this time. One place that can be bothersome is the joint between the black desolder end cap and the yellow desolder chamber. To seal it, put a small amount of petroleum jelly on the joint. This joint must not be sealed with anything that that will prevent it from opening. This joint is used to periodically open and empty the solder chaff.

After you have verified and fixed any air leaks, you are ready to try it hot. Plug in the iron and give it a try. If you have never used a vacuum-desoldering tool, you will need a little practice. There is a technique to using this unit. Push down the vacuum pump. Place the desoldering tool over the IC pin. Allow the solder to heat and flow. Now take the pencil and circle around the pin so as to get the solder loose on all sides. Now let the pump go while you continue to circle around the pin. Now take the iron off the pin. Typically I have the solder gone and iron removed before I reach the end of the vacuum suction. To remove the component, take a wooden stick (chopstick works well) and gently push each pin back and forth to verify they are free. This action can also break loose any tiny solder that might still be holding inside of a plate through hole. The IC will often fall out on its own or with a little push on its pins with the wooden stick. Note that a wood stick is best because it is non-conductive and not prone to static buildup.

As with all tools, the more you use them, the more skilled you become with them. I would recommend that you practice on junk electronics before you try to repair an expensive rig or recover a no longer available IC. If you can find old VCRs and ISA computer cards, they generally have a lot of through hole components. Old and current PC power supplies are also good places to find practice parts. Remember that the iron is only 30 or so watts, so it will not desolder large components well. Tiny push switches, transistors, and DIP ICs are easily removed. First item I tried after getting this working was a 40 pin DIP chip which came off like I was an old pro at this.

Obviously, this desolder tool is not for every desoldering job. I’m sure that once you’ve used this foot-operated vacuum desoldering station, you’ll seldom if ever go back to the old ways of desoldering small through hole components.

Mark suggested that it may be possible to “front end” the modified foot pump with standard Soldapullt type unit. Although we’ve not tried it, it looks like it would create a large vacuum capacity desolder suction unit. Used with a larger wattage soldering iron, it may work well for larger solder joints like those found in older tube type equipment.

Parts list:

Foot-pump $4.99 lumber store
3/8 in ID 10 ft vinyl hose $2.78 lumber store
silicone caulk $2.98 lumber store
7/32 OD Brass tube $1.75 RC hobby shop
Brass shim stock $3.25 RC hobby shop
Desoldering iron $12.95 Midwest Surplus Electronics or other online stores and Hamfests

Member Comments:
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$30 DIY Desoldering Station  
by K1CJS on September 28, 2012 Mail this to a friend!
I bought a refrigeration vacuum pump that runs off a compressor (uses a venturi effect for the suction) from Harbor Freight to make my de-soldering tool. I've re-worked it a couple of times and have finally settled on a set-up that uses a vacuum reservoir off the suction port of that pump and a hose with a small push button valve and a small copper tube that will suck the solder off the PC board.

Yours is a bit better, since it doesn't need the continual air feed off the compressor to maintain the suction. Good job!
 
$30 DIY Desoldering Station  
by KE4ZHN on September 28, 2012 Mail this to a friend!
Nice! Hats off to you for making your own desoldering tool. You must have great eyes to work on these fly speck boards of today. Surface mount may be wonderful for making electronics compact but it sure sucks to try and repair.
 
$30 DIY Desoldering Station  
by W5HLP on September 28, 2012 Mail this to a friend!
Ron,

Brilliant idea and an outstanding homebrew project - great addition to the toolbox and well put together article. Excellent use of photos and discussion of thought process as well as construction details. I will be building one this weekend.

73
Herm
W5HLP
 
RE: $30 DIY Desoldering Station  
by K9MHZ on September 28, 2012 Mail this to a friend!
Ron,

You should contact the editors at the League to have that included in a future issue....it's that good!

 
RE: $30 DIY Desoldering Station  
by K0BG on September 28, 2012 Mail this to a friend!
Not too shabby for a home brew sucker-outer! Once upon a time, Harbor Freight sold something very similar, but it cost about $40.

Inexpensive workarounds are fine if you don't do a lot of SMD work. I do, and if you do, it pays to spend the bucks for a decent hot air rework station. One of the better ones comes from these folks: http://sra-solder.com

Alan, KØBG
www.k0bg.com
 
$30 DIY Desoldering Station  
by PG00023016 on September 28, 2012 Mail this to a friend!
This was a very nice usable story for me. I hope to implement it in the near future. Thanks!
Kevin N5BAM
 
RE: $30 DIY Desoldering Station  
by W9PMZ on September 28, 2012 Mail this to a friend!
Hot air blowers are ok but the have an inherit issue. If the board is densely populated, especially 02/04 parts, they get blown away pretty easy. Not for a newby...
 
RE: $30 DIY Desoldering Station  
by WD8SBB on September 29, 2012 Mail this to a friend!
Thanks for the accolades everyone. It seems to do very well every time I use it. There are some pins which seem to be more difficult to get. I think the PCB hole is smaller diameter, but have not really investigated. I just resolder the pins and try again.

Oh that is something you need to remember. If it is not working, go back and resolder the joint. Unless there is plenty of solder, the heat will not "flow" through the entire joint to allow all the solder to melt

As for the League publishing idea. They accepted it like a year ago, and then notified me the other week with a sorry, it didn't fit where they were going to publish it.

Go figure.
 
RE: $30 DIY Desoldering Station  
by W8AAZ on September 29, 2012 Mail this to a friend!
They probably are taking ads for the "expensive" models and your plan did not "fit" next to those!
 
RE: $30 DIY Desoldering Station  
by N8CMQ on September 30, 2012 Mail this to a friend!
Excellent idea!
I love the pump, nice and quiet compared to my Weller station.
One tip for your solder reservoir, add a cotton ball at the vacuum end to keep solder and flux vapor out of the hose.
 
$30 DIY Desoldering Station  
by W8LV on October 2, 2012 Mail this to a friend!
I love to see someone put a nice thing together like this, and share it with us.. well done, in the true spirit of the radio art.

I couldn't afford hakko either, but needed an ESD safe setup. ... which is how I stumbled on the Honest Abe of the Soldering World!

If you ever need an ESD setup as an adjunct, try here:

http://www.eham.net/reviews/review/108715
 
RE: $30 DIY Desoldering Station  
by KD8MJR on October 2, 2012 Mail this to a friend!
Nice Job But.....

I own a Xytronic 988 and I noticed that they use a cylinder in the air line that has a cotton filter in it, this cotton accumulates lots of little solder bits that get past the main wire filter. You should add something like that because during the desolder operation some very tiny little round balls of solder get created and they will get sucked down the line and eventually mess up your foot pump seals.

Simple fix is probably putting a Gas line filter for a riding mower into the air line.

Robert
KD8MJR
 
RE: $30 DIY Desoldering Station  
by WD8SBB on October 2, 2012 Mail this to a friend!
Wow, there seems to be some really good rework stations that I had not seen. May get something from Santa this year, hi :-)

I also notice that I have the wrong URL for Midwest. Sorry. http://www.midwestsurplus.net
 
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