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darryl
03-12-2010, 09:45 PM
I promise I'll get back to metalworking soon. I seem to be posting a lot of OT lately-

This one is about desoldering tools- I have one of those spring loaded plunger types, where you heat the joint with a soldering gun or whatever, then pinch the trigger on it and it jumps off the board while you're trying to keep it there sucking the molten solder away. It works- I don't like it.

I use solder wick a fair amount, but it takes quite a bit to clean up a join. It has its place, but not for general unsoldering of power transistor leads, etc. Next- we have an expensive motorized unit that sort of does the job, but it's dying and I'm looking for a better solution, simple and easy. I also have one of the bulb type units, which has died, but was kind of marginal anyway because of the limited amount of suction you got for each squeeze of the bulb.

I'm getting there- I have my vacuum table, which would work well, but is too cumbersome for use in my small electronics room. I have motors, most run too fast to make a piston type vacuum pump for the intermittent sucking action required- overkill I guess is what this approach seems like to me.

I have a toilet plunger, one of the red ones. It has sort of a snap action to it, and I could easily rig it up on a board with a hose and one way valve. I would press it by hand, then pull a trigger or whatever to initiate the release of it to give the instant suckage action to pull molten solder into the hose through a nozzle. I'm not concerned about heating the nozzle- I've got that figured out. It's the initiation of the suckage that concerns me, and the strength of the suck-

This topic really sucks, I know :) I want to keep this thing simple so I can put it together in an hour or two. It can be set on the floor and I just stamp on it to reset it for every use, not a big deal. Every so often I'd take it apart to remove all the solder, etc. I can add a spring to increase the suction power, and I can think of two methods to activate it. One means operating a quick-acting valve near the nozzle, and the other requires a latching assembly of some kind that would release electronically or mechanically. The hose would be simple vinyl tubing, with a short high temperature piece of probably silicon tubing to go from the actual hot nozzle.

Anybody care to comment on this ? I'm basically looking to make a sort of foolproof mechanism to give a quick single shot suck without clogging up.

EddyCurr
03-12-2010, 09:59 PM
The hose would be simple vinyl tubing, with a short high temperature
piece of probably silicon tubing to go from the actual hot nozzle.You might want to have a contingency in place to fall back on
- I believe that conventional vinyl tubing might collapse sufficiently
to impair operation of this device. Though less flexible, perhaps nylon
tube might stand in if vinyl happens to struggle.

.

darryl
03-12-2010, 10:27 PM
Good point about the tubing collapsing. I'm also concerned about the diameter of it- it needs to be large enough to allow a fast enough surge of air through it to get the job done. For the short section of silicon tubing I can just surround it with a section of a slightly stretched spring of suitable size.

Can't find the piece of silicon tubing I know I have:( No matter, I can get by with just the vinyl- the first section can be a piece of stainless tubing, with a bit of a heatsink attached before the vinyl goes on. That should be good enough. In fact, the heatsink might as well be the handle, and the piece that holds the latch release trigger.

An idea is coming together now-

I'm almost coming full circle on this. I'm finding that the toilet plunger rubber is not very 'fast'- it's not rubbery enough. Now I'm thinking that the spring-loaded plunger, as in the solder-sucker I have, is not a bad idea- I could build that as a sort of stand-alone tower to sit on the benchtop, with just a short length of tubing going to it from the nozzle, plus a cable release mechanism to trigger it. Punch it once, it latches, pull the trigger, it works. A little chamber in the bottom catches the bulk of the solder before it gets to the cylinder. Hmm- I'll think about that while I have dinner.

rdfeil
03-12-2010, 11:04 PM
Darryl,

I have also thought about doing something like you are thinking about. I personally like the spring loaded plunger type desoldering tool but for larger jobs a GOOD vacuum system would be much better. I have a Weller vacuum station and never use it, BIG waste of money. It is a neat idea but not enough heat or vacuum. I thought about using a vacuum pump and a reservoir tank to provide the vacuum source to a handheld nozzle system. My thought was to use a solenoid valve and a timer to make a pulse vacuum system. Push a button on the handheld unit and the timer triggers the solenoid for a preset amount of time. The time would be figured out by trial and error. The only other thing you would need is a small filter to keep the solder out of the valve. A good filter for this would be a small chamber filled with cotton balls. The chamber could be as simple as a small pipe coupler with hose barbs screwed into the ends. Easy to clean and fairly small. Or to get back to machining you could machine the filter chamber :D .
Now that I have described my idea maybe I should get to building it :rolleyes: .

Hope this gives you some ideas.

Robin

Black_Moons
03-12-2010, 11:11 PM
I made such a device that attachs to a normal vacuum cleaner
What I did, i was I used a broken aluminum arrow (had it handy, basicly a 1' long aluminum tube thats about 5/16" ID and super thin wall) withe tip crimped slightly and filed to a 45 degree angle (for conviance to get into the area to suck without obscureing the iron)

plugs into a 2' long vinyl 3/8" ID tube, and at the end I made a 'plug' outta toilet paper and electrical tape, this goes into the end of a normal vacuum cleaner

By the time the solder has made it past all 3' of tube, its solid and won't stick inside the vacuum cleaner or harm it. most solder seems to solidify inside the 1' long tube, and while sometimes clogs up, being aluminum the solder can be very easily scraped off. Very little sticks to the vinyl tube, and what does can be easily scraped off when it accumulates.. Or replaced at $1/ft.
Warning don't use a small tube much longer then 2' or you'll lose a lot of suction. idealy even use a thicker tube after 1', its best to have some thin tube at the end however for ease of flexability.

Don't run the vacuum for very long like this continiously as most use the air to cool the motor and it can overheat the vacuum, maybe add a vent to the hose.

fasto
03-13-2010, 12:03 AM
I have a Weller vacuum station and never use it, BIG waste of money.
Robin, I have a Weller WRS3000 motor-driven vacuum desoldering station and it works fabulously. It is a $1500+ tool, though.


Anybody care to comment on this ? I'm basically looking to make a sort of foolproof mechanism to give a quick single shot suck without clogging up.
Pace makes an air-powered desoldering unit, using a venturi to generate vacuum from shop air. You could try that technique.

Black_Moons
03-13-2010, 12:06 AM
Does anyone have a refrence on venturi design? Ie like how to make a high vacuum low flow one or a high flow low vacuum one? rules of thumb for the 'cones'?

lakeside53
03-13-2010, 12:57 AM
I have a Pace machine... Mine has a conventional vacuum pump.

The solder is contained within a glass tube right at the handpiece. Felt filters stop it from processing down the tube.

rdfeil
03-13-2010, 12:59 AM
Fasto,

I will check the model number on mine but it sounds like the same one based on price. Mine is quite old now (15+ years and cost about $1000 then) and the big problem is that the tip cools way to fast when it is sucking. The tip also had a tendency to clog quite easily. It is quite possible that I just expected more than it is designed to do :rolleyes: (I do that often). I found it really struggled to desolder on double sided boards without doing damage to the board because the heat transfer was simply to little to slow. I am a big believer in a fair amount of heat so I can get in and out quickly. Modern circuit boards just don't like the heat to stay for a long time it seems. I will confess that a newer machine ma well work better but once burned I normally wont grab the wrong end of the soldering iron again :p

Robin

darryl
03-13-2010, 01:38 AM
The system I use at work is also an expensive station. I think it's an Edsen- something like that- anyway it has been said that it works well, but in my experience it's a little slow and finicky. Maybe just because it's old and has problems- I know that it uses a motor driven pump, and all that happens is that when you pull the trigger, the pump runs and the tip sucks. Now I'm a little torn over the idea of how fast the air should be drawn through in order to give a good desoldering action. I have been of the opinion that it should be a quick pulse, but maybe a steady draw is just as good, or even better.



Two of our techs use it a lot more than I do, and they are used to it so maybe the only issue to them is that it's intermittent. It's probably going to be up to me to fix it, but I feel it could work better. I could be wrong about it.

I've just got done making a tip from some printer rod. My aim was to see how well it would take solder, and whether it would melt solder quickly when brought into contact with a join. In the past I haven't had much luck soldering steel, but this stuff took the solder like it was copper. Now I'm wondering if this is leaded steel, and maybe for that reason it's working that well. It sure turns easily, and leaves a nice finish. It almost seems like I could peel a shaving off it with a fingernail, it machines that easily. Of course I can't do that- I'm not Chuck Norris :), but this is leaving me wondering if this might actually be a suitable steel to make tips from.

What I plan to do now, and this project is going to take more than a couple hours, is to find the stainless tubing for the stem, make a couple tips, make a way to secure the tips, then wind a heating element on the stem, using some fiberglass cloth and furnace cement, like I've done in the past. Not sure where I'll go with temperature control, but I'm not going to worry about that just yet. I want to see if the steel tips can conduct heat quickly enough to a join to melt the solder without having to be too hot beforehand.

In any event, I do need to know which approach is best- steady suction, or a quick 'spurt' of vacuum.

Just looked it up- it is an Edsyn, and the one we have is 900$ cdn plus- I'm even more convinced to make my own now.

lakeside53
03-13-2010, 02:07 AM
My Pace just has continuous suction. You can adjust the suction from the panel. Most times I leave it set fairly high, but it works fine on a single tip even when low.

I addition to the head filters, there is another paper disk filter in the vac line.

If you want I can take some pix of the hand-held head device assembly parts, and filters. It's quite simple and has been around for a very long time. Mine is from the 80's and I can still buy any part for it. I had a later model at one point, but it didn't work any better for single point operations. I still have the heads from it for surface mount devices.

It might make sense to buy parts for the trickier-to-make components. Tips are quite cheap and IIRC are nickel plated copper.

darryl
03-13-2010, 02:59 AM
Thanks, Lakeside, for that offer. I've had a pretty good look at the components, so I won't need that.

I've just been looking at the tips, and they are described as steel, or iron plated (not sure on what base metal though). I've just been reading about rosin fluxes, and I find that the one I have is 'activated', and a no-clean formulation. That could explain how I could so easily solder the steel tip I made with it. It might be that the type of steel has less to do with it, or it could be that the particular steel I picked to make the experimental tip is a good choice- I don't know, and I haven't been able to find out anything relevant to soft soldering steel.

One thing that concerns me is the heat transfer rate through steel. I have to assume it won't be a problem, because Edsyn themselves make some of their tips from steel. I do see that they have a fairly steep taper- in other words the steel tip gets fat quickly behind the point, presumably to minimize any problems with the heat transfer rate. I could buy tips- they are cheap enough, but I can also make them in about three minutes. If I make them, they will fit the holder I make exactly.

I've also considered to put a copper jacket over the tip, both for fast heat conduction into the steel and for faster heat transfer to the point. I don't know if this will be a considerable improvement, or if it will prove to be problematic. I would press a copper sleeve onto the steel tip, but it might not take many heating cycles before the sleeve comes loose. I just don't know. What I could do is compress the ends of the sleeve onto the tapered portion of the steel tip, with the back of the tip being tapered a bit as well. Even if the sleeve became loose, it wouldn't be able to slide off. I think maybe that's what I'll do, so then that will define the holder I make for the tips. I could just forget about adding the copper-

Making the heating element will be fairly straightforward. The one thing that would make it better for me is if I could spot weld a section of a better conductor to the nichrome element wire, but so far I've been able to get away without having to do that. I've made probably 6 or 8 different heated tips for various applications, the most powerful of those being about 300 watts. That particular one blew up on me in a flash one day, but I know why it failed and I won't repeat that mistake. Others have been for welding plastics, and one was for a replacement tip for my 3 volt soldering pen.

I've had considerable fun doing these things, so it's not like I'm just trying to save a buck, I actually like to do it.

Black_Moons
03-13-2010, 06:43 AM
how did your nicrome element blow up?

Evan
03-13-2010, 07:03 AM
Making the tip from iron is not going to work Darryl. In fact I have been considering making a couple of tips for my iron from silver for doing smd soldering. Desoldering is easy, I use hot air and slap the board on the bench (salvage work :D)

vpt
03-13-2010, 09:37 AM
This is the one I have, works alright. I use it for desoldering auto ECU's for chipping them.

http://www.curiousinventor.com/images/how_to_solder/desoldering_tools.jpg

fasto
03-13-2010, 12:19 PM
Desoldering is easy, I use hot air and slap the board on the bench (salvage work :D)
When the continuing existance of the PCB is not an issue, I have been known to use a propane torch and bang the board on the bench.

fasto
03-13-2010, 12:23 PM
Mine is quite old now (15+ years and cost about $1000 then) and the big problem is that the tip cools way to fast when it is sucking.
Hi Robin, if your desoldering handpiece is more than 3 or 4 years old, it's probably a DSX80 or something like that. These handpieces are a real piece of German made junk (see! Even the Germans can make junk!). My station came with this, and I had exactly the issues you are saying: poor heat transfer to the tip.
When the heater burned out in my desoldering handpiece, I found that Weller now sells a DSV80 and it's about a million times better. We use this for production soldering and rework, and it's in use 4 or 5 hours a day, 7 days a week.

nheng
03-13-2010, 12:45 PM
I had an Ungar desoldering station which was quite useless but it turns out had a very nice pump inside, similar to some of the small air brush compressors. It gets used for two things now ... vacuum packing large bags of clothing for kids college trips and is now sitting as a chip blower on the mill but is soon to be removed from that duty.

Haven't done any thru hole work in a while and SMT has its own challenges. With the right tools it becomes a piece of cake, far simpler and quicker than thru hole ever was. Weller has its ups and downs but their SMT system with tweezer handpiece (multiple tips for soic, tssop, resistors, etc.) and micro sized iron, auto shutoff, 6 second re-heat that REALLY WORKS. If you ever used the micro sized princess from Weller you know how bad or impossible tinning can be. Not so with this new system. I forget what it cost but it was probably in the $400 - $1000 range with variety of plug in tips.

Regarding a snap vacuum source, I have an SMT vacuum pickup system that has a foot pedal and vacuum unit. The vacuum unit is about 2.5" square x 7" long. Inside is what looks like a clear polycarb cylinder with aluminum pistion and O-ring and a big a$$ed solenoid behind it. The thing SUCKS.

As mentioned, you will want non collapsing tubing and and possibly an intermediate chamber with some baffles to catch the molten solder. You may be able to create a 2 stage system which charges a hand wand with the solenoid sucker and you locally release the vacuum at the wand. This would give you the best, quick snap action and the hose would be less critical.

Den

Black_Moons
03-13-2010, 01:38 PM
you don't need non collapseing tubing, any stiff PVC tubing 1/2" and under won't collapse under light vacuum (good flow is whats important). Cheap too, like $1 a foot or less.

Expect the tip and tube to get solder stuck to it. Not a problem, just use the right alloy sucker tube and all the solder will peel off by just jaming a wire up the sucker hose with the vacuum on. most of what sticks to the (clear, easy to spot clogs forming pvc) tube can be scraped off with a coathanger or 3/16" mild steel rod with only slightly more diffaculty. Or just buy a new $2 tube every few months.

After a few feet of tube, no solder will be molten anymore and should be safe to catch in a bag/filter/whatever, its just little fragments of metal once it cools. Hell you'll notice in the clear tube no solder gets stuck past about 2' of tube, about the absolute min length you'd want to have a wand from the station for conviance anyway.

darryl
03-13-2010, 04:56 PM
My element blew up because I left a void in the furnace cement that I used to encapsulate the element. A short length of element was left exposed. My power supply for that tool has a few taps on it so I can select the level of power applied to the tip. I was soldering copper trays at the time, and that sucks a lot of heat. The tip was a chunk of solid copper about an inch square by about an inch and a half long. One end was turned round to wrap the element onto, and the other was faceted so it would come to a point.

I had the thing powered up a little higher than I usually did, and the exposed section of element gradually got dull red, then a brighter red, then it sort of ran away. It quickly got white hot, then blew out with a bang and a lot of smoke.

Once the resistance of that section started to go up because of the heating, the power tended to concentrate there and make the problem worse. It's the same thing with any element.

A good example would be hot wire foam cutting. Before you plunge the wire into the foam, it will be a consistent color all along it. Once you cool the part that has entered the foam, the rest that's exposed will brighten up.

With my soldering tool, I should have gone back and filled that void with more cement, then waited for that to fully cure before applying current. I just got lazy, plus I needed it so I pressed it into use before it was really ready.

Evan, you said that making my tip from iron is not going to work- I'm just wondering about your reasoning for that- Edsyn makes some of their tips from steel, and others they say are iron plated- they must work to some degree. I'd rather go with silver, but I just don't seem to have a chunk of that laying around :) I'd make them from copper and keep them tinned- I need to find some solid copper rod-

EVguru
03-13-2010, 05:34 PM
I have the older version of this at work;

http://www.rapidonline.com/sku/Tools-Fasteners-Production-Equipment/Soldering-Equipment/Solder-Removal-Rework/Lead-free-desolder-hot-air-station/77411/85-1156

It's worked well for about four years now. I've had to change the desolder element twice in that time.

jdunmyer
03-13-2010, 08:21 PM
Years ago, I had one of those desoldering gadgets such as in Post #15, bought from Radio Shack. Removed the bulb, ran vinyl hose to a venturi mounted on a solenoid valve. Attached an air hose and foot switch to the SV and went to work, it functioned great. The venturi was simply removed from a siphon blow gun, I didn't bother trying to make one from scratch.

darryl
03-13-2010, 10:25 PM
Well, nothing to show yet, though I'm coming along with the idea. I found a chunk of copper today which is a quarter section of a circle which would have been about 7 or 8 inches round, and it's 1 inch thick. I cut a piece out of that, and after turning it, ended up with a round slug 1 inch long and nearly 1/2 inch diameter. I'll further machine that to make the tip from.

I'd like to try something different with the heating element so I can eliminate the usual problem of having some exposed so that a connection can be made to it. The idea is that the element becomes one component, the tip is another, and the handle is the third. As the two-part handle is tightened, connections are made to the element and the element is squeezed to the tip, which secures it plus makes for best contact from the element to the tip for fast heat transfer. Basically you loosen a screw and the element opens up just enough to slide the tip in or out. I'm going to try to work that out.

Where the tube comes out the back of the tip for air to be drawn through- that can enter the side of an aluminum tube using a high temperature gasket, then another hose can come off the aluminum tube somewhere else. The molten solder can collect in there, and whatever filter is first in line will be in there. That part will not have any threaded end cap to it- it will clip into place to become sealed against a silicon gasket, and come off just that easily for cleaning. It will be a part which gets hot, so some shielding will have to be part of that.

I'm sure I'll have the vacuum system worked out- the little pump I have is probably going to be enough, since no manufacturer seems to have found that anything more is needed. That's it for now- I'm going to do some experimenting .