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Thread: Mini Soldering Iron?

  1. #1
    sydneywellman is offline Plastic
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    Default Mini Soldering Iron?

    I work in a physical chemistry lab and we have this piece called an octapole (see picture octapole1_broken.jpgoctapole1_shape.jpg) and I broke where some of the little rods connect to these two plates. We believe we can re-solder the connections however some of them can't be accessed by our size soldering iron (Weller TC201T) since the diameter of the soldering rod is too big and would melt the plastic.

    Essentially it's 8 little round poles arranged in a circle going through the center of two plates. Some of the poles are attached to the first plate and some to the second and the distance between the first and second plate is about 7mm. I've found I can get a tip end through this 7mm space however because the plates have a radius of about 1.5cm, before the tip even reaches the center the thicker part of the solder rod touches the plastic covering the plates keeping the tip from reaching the pole and also would melt the plastic.

    Does any one know of any soldering irons which are more pencil-sized all the way along the rod which might work for us? I search "mini" however just about every rod is considered "mini" but not in the way I'm looking for!

    Any referrals to a soldering iron product which you think could fit these specs would be much appreciated!

  2. #2
    robosilo is offline Aluminum
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    sounds like you need a soldering iron that has a fine pencil tip. Weller makes good stuff otherwise the digital soldering iron that radio shack offers is half way decent. They don't actually make the unit, they just slap their name on it. It's actually made by Madell and if you go to their website you can get additional tips. There is a pretty good assortment and they make a few other models of soldering stations and hot air stations. In fact you may almost be better off with a hot air station on real small stuff.

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    cvairwerks is offline Aluminum
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    Look for something like a Weller WD1000M series setup. You want something with a micro iron and the tiny tips. Here is a link to the catalog for Weller, over on Digikey's website. Shop around on price tho, as Digikey is not always the least expensive.

    http://www.digikey.com/Web%20Export/...f?redirected=1

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    cidrontmg is offline Plastic
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    There's a gadget called "Coldheat", it's ColdHeat - Wikipedia, the free encyclopedia, Weller sells them, and also see Amazon.com: ColdHeat Classic Soldering Tool: Home Improvement. I have one, have worked some electronics, but see what's going on, and if it's the one he really wants. Soldering surely works, no doubt about it, but it's not a miracle for everything possible soldering applications, and it's a rather delicate piece of equipment, like forget everything about robustness. Think about baby's eyes...
    The tip is very small, and the heat is really concentrated, the rest of the gadget remains always cold. I think it will be quite easily to solder the pads you're wanting to do. The Amazon cost is $22.95, it works with two AA batteries (!), cordless, of course, instant (ON-OFF) heating, and something 100 g weight.

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    Solo Inventor is offline Aluminum
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    I might get laughed at but I really like this little soldering iron. RadioShack Electronic and Hobby Soldering Kit : Soldering tools & supplies | RadioShack.com I'm not sure if it will fit but it might be close. You could always take your gizmo the Radio Shack and see if it will work before you buy it. I'll measure mine when I get home later tonight and add the dimensions to this post if it would help.

    Ok, I can measure it now. The diameter of the 'shaft' part in front of the handle is about 0.190" and the distance from that odd round disc out to the tip is about 2.2" The disc is rather well attached. I'm guessing it partly acts as a heat sink but it also keeps the tip away from the table when you set it down. If you cut it off you'd have about 2.55" before you got to the handle.

    While I'm talking about soldering irons, one trick I learned is that with the new lead-free solders, it's best to leave a big blob of solder on your tip when you turn it off. The tips seem to last a lot longer than if you shut if off while clean.
    Last edited by Solo Inventor; 08-16-2013 at 06:35 PM. Reason: Added more info

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    Forestgnome is offline Stainless
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    You could try resistance tweezers on the pin to heat it up.

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    CalG is offline Titanium
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    Just wrap a piece of copper wire tightly around the soldering tip you have. Make an "extension", you can shape the wire to whatever form you require.

    Give the set up an extra minute to warm up, tin the tip, Work under magnification, and be gentle with that tip. Copper can be soft. It's heat, not pressure! ;-)

    Oh! Thin your solder too. puond it out flat and cut it with a raxor blade. hold onto the solder piece with a split cotten swab wooden shaft/

    Life ain't hard every day!
    Ray Behner and bhigdog like this.

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    adama is offline Diamond
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    If you have access to a lathe and some copper rod a tip is dead easy to make (well as easy as turning copper ever is). Simply pick a soldering iron that makes it easy to fit a tip you can easily make. I prefer making them for my mains 25 watt fixed temp antex soldering iron. Whats nice about a copper tip is it heats up damn quick! Disadvantage is every so often you have to refile it a bit, but its not often enough to be a issue, sure is a lot nicer than a typical tip that does not want to take the solder too! Thinking about it, i think its had one of my home brewed tips on there for a fair while now.

    On another note whats a octopole actually do, sure looks a nicely made little bit?
    eKretz likes this.

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    To make turning the copper easier, use whole milk as a cutting fluid (no joke). One problem with a really long, thin tip is that as it heats up, it will flex.

    --Hawk

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    bruto is offline Stainless
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    Not sure what actual size is needed here, but the smallest soldering iron I have come across is the Ungar 6902 with the 6910 tip, which is only 10 watts. The rod is approximately 6 centimeters long, of which the first 5 CM is a diameter of 5 millimeters, and the last centimeter is a copper tip that is 2 mm thick at most.

    It looks as if Ungar now is part of Weller, but I think the rig still exists somewhere.

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    9100's Avatar
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    I must have had at least 30 soldering irons over the years. For small work, I use an American Beauty, I think 55 watt (I'm at home, it is at the shop) and have a collection of tips from them. When I worked with professional gyro builders, they used similar irons with a reasonable amount of heat storage and had machinists turn down tips to suit the job, as Adama and Reb suggest. I hate the mini irons with no mass that go cold as soon as you suck a little heat out of them. I have one of the mini Wellers and a soldering station that I haven't plugged in for at least 10 years. You want that tiny tip backed by a heat reservoir. A co worker described English model makers using a circa 150 watt iron with a long tip tapered down to a point. They had the iron on a stand and would bring the tiny parts up to the tip, just touching for an instant. He asked why they didn't use a smaller iron and the answer was that they wanted a constant temperature with the heat replaced quickly when they soldered a part. Same idea.

    Bill

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    Solo Inventor is offline Aluminum
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    Quote Originally Posted by bruto View Post
    Not sure what actual size is needed here, but the smallest soldering iron I have come across is the Ungar 6902 with the 6910 tip, which is only 10 watts. The rod is approximately 6 centimeters long, of which the first 5 CM is a diameter of 5 millimeters, and the last centimeter is a copper tip that is 2 mm thick at most.

    It looks as if Ungar now is part of Weller, but I think the rig still exists somewhere.
    That one sounds a lot like the Radio Shack one I mentioned back in post #5. The Radio Shack is 20 watts though but it seems like more since it doesn't have so much surface area to radiate heat. I had one of those little skinny irons back when I was in grade school. I really missed it when it finally broke. I was so thrilled to find something like it again and now I use it as much as I can. You don't realize how annoying that big fat tube is until you've tried a skinny iron.

  13. #13
    awander is online now Aluminum
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    It looks like that unit can be disassembled, which would likely give you easier access to the connections on the top plate.

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    jim rozen is offline Diamond
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    Good call on that. It'll have to be disassembled to repair. Basically you ask yourself, how did
    they assemble that thing? And then simply do what they did in the first place. Usually that
    means taking it apart to start.

    From the photo it looks like the brown polymer the supports are made of, are *probably*
    SP-1 Vespel. If that's the case, then the soldering iron won't come close to melting it, or
    burning it, or doing anything to it.

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    Forestgnome's Avatar
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    Quote Originally Posted by jim rozen View Post
    Good call on that. It'll have to be disassembled to repair. Basically you ask yourself, how did
    they assemble that thing? And then simply do what they did in the first place. Usually that
    means taking it apart to start.

    From the photo it looks like the brown polymer the supports are made of, are *probably*
    SP-1 Vespel. If that's the case, then the soldering iron won't come close to melting it, or
    burning it, or doing anything to it.
    Most likely put together with fixtures. You'd have to do the same if you took it apart.

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    Marty Feldman is offline Stainless
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    Have a look at the custom soldering tips, which can be made in a variety of diameters & lengths, here:

    http://www.antex.co.uk/soldering/

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    A_Chemist is offline Plastic
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    Quote Originally Posted by adama View Post

    -----snip----
    On another note whats a octopole actually do, sure looks a nicely made little bit?
    RE: The function.
    I'll guess. Its an ion trap out of a mass spectrometer.

    To the OP:
    I believe you need more than a soldering iron.

    It is already broken, disassemble it the rest of the way.

    The positioning of the rods is important for the quality of your RF field, right? You need a jig to hold the rods and plate in the exactly proper spatial relationship. Having that, then solder it using a hot "air" tool as mentioned above.

    And, are you sure that is garden variety tin-lead solder?

    Best,
    Chris

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    sydneywellman is offline Plastic
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    Hi Chris,

    Yes it's one of the octapoles which guide the ions to the ion trap in a mass spectrometer.

    We are working on having our machinists here at the university create a teflon spacer which will hold all our guys in place as you're right, the RF field that's generated by the shape is important.

    It's also not tin-lead solder we don't think. We need something that's safe under high vacuum (we were thinking silver solder) however there is a lot of solder already on the piece so we wondered if just using a bit of fresh flux with the metal that's there it might work to reseal the pieces. Maybe you can comment on this idea however?

    Also, will the soldering irons above heat enough/work for silver solder? This will be my first soldering job so I'm fresh in the learning curve.

    Thanks for the comments everyone. This is a handy bunch of ideas to get started with!

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    sydneywellman is offline Plastic
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    An updated picture which is probably more helpful to envision the space I have to work with:

    octapole.jpg

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    If it is silver solder then a soldering iron will not work. Not nearly enough heat. You might try playing around with a very small diameter carbon rod and a power supply. That's how those little tweezer type soldering irons work. I would suspect that would be plenty of heat if it is silver. I think you have got to take this thing apart and come up with a fixture as has been suggested and you mentioned. I have a "little torch" that has tips that go down so small that the entire flame is only 1/8 " long. Works great with silver.

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