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  • HO RacePro
    replied
    Soldering Pre-Forms

    Soldering is not only used by hobbyists, it is also an industrial process, and used for more than just electronics. It can be used for mechanical assembly in the 'real world' too.

    One way to industrialize mechanical soldering is to produce and use what are known as 'solder pre-forms'. That is, parts made of solder that are fitted up into the assembly, often with flux printed on, and then heated to the point where the solder melts and fuses two or more parts of the assembly together.

    Solder pre-forms can be used by hobbyists too. And they can be a great aid in making precision assemblies. An example follows. I wanted to make a front axle assembly with independently-rotating front wheels. The key part was a thin brass washer that was a tight fit on the axle. I soldered that washer onto the axle using a solder pre-form made of Stay-Brite solder, and a small drop of Stay-Clean brand solder flux. I needed to use those soldering products because the axle was stainless steel, and ordinary solder would not stick to it.

    This first photo shows how I made the solder pre-form, by wrapping a length of solder about the axle. I used a needle-nosed pliers to get the solder tightly wrapped around the axle, then I cut the pre-form off with diagonal cutters. I made two solder pre-forms.





    I clamped the axle in a bench vise, then assembled the wheel, and the washer onto it. I applied a very small drop of Stay-Clean flux on top of the washer, then put the solder pre-form in place, on top of the washer. See below.





    Finally I heated the end of the axle with my miniature propane torch, melting the solder pre-form and attaching the washer to the axle. The finished assembly is seen below.




    I cleaned that up a bit with a Dremel tool and wire brush. I used the second solder pre-form to attach another washer to the other end of the axle.

    Solder pre-forms can be made in any shape and size, and used for many jobs. All it takes is a little ingenuity. For example, if you wanted to make a wide, flat solder pre-form you can take ordinary solder and hammer it flat on an anvil. Need a hole? Drill a hole. Or you can take a thin sheet of brass or copper, tin both sides, and cut out the shape you need. I'd still call that a solder pre-form.

    Take it from there!

    And, just in case anyone is curious, here is the miniature propane torch I use for much of my soldering these days. It doesn't have an igniter built-in, so I light it with a cigarette* lighter. No biggie.

    Ed Bianchi





    *Cigarette: Analog precursor to modern vaping appliance.
    Last edited by HO RacePro; 01-06-2019, 04:22 AM.

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  • Kevan
    replied
    Blow torch

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  • HO RacePro
    replied
    If you are looking for one of these ceramic blocks, Google "Honeycomb Ceramic Block". To find the pins Google "Honeycomb Solder Pins".

    My ceramic block is a half-inch (12.7mm) thick, so it does an excellent job of protecting my wooden benchtop from the torch flame. (And just to be clear, by 'torch' I am not referring to a flashlight. So what do you Brits call a propane-fueled heating appliance?)

    Ed Bianchi

    PS - The Three Laws of Thermodynamics
    1) You can't win.
    2) You must lose.
    3) You can't get out of the game.
    Last edited by HO RacePro; 12-14-2018, 10:32 AM.

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  • GT6
    replied
    Originally posted by Wet Coast Racer View Post
    ...I'm guessing that ceramic plate also dissipates the heat pretty quickly.
    Just the opposite, Wet; because the ceramic material dissipates heat slowly (i.e. it acts as an insulator) almost all the heat from the soldering iron (or torch) goes into the metal part you're trying to solder and not into heating up the big block of material that it is sitting on - think about how difficult it would be to solder something clamped to a big slab of aluminum plate.


    Remember, entropy always wins, but there's no point in helping it bring about the heat death of the universe any sooner than absolutely necessary


    cheers
    Scott

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  • Wet Coast Racer
    replied
    Clever stuff. Interesting to learn about the properties of aluminium and stainless steel.

    I'm guessing that ceramic plate also dissipates the heat pretty quickly.

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  • HO RacePro
    replied
    I have recently come across two new soldering accessories (new to me at least!) -- and I have fallen in love!

    One is a ceramic plate perforated with a precise and tight pattern of through-holes, which is so very excellent for fixturing parts to be soldered together. The other is a pack of stainless steel pins, with tapered ends, designed to fit in those holes. The tapers make it possible to closely fixture parts that do not exactly fall within the spacing of the holes in the ceramic plate. Both are shown below:



    I bought both items on eBay for less than US$25.00 total. The ceramic plate is available in a number of sizes. The one I bought is 5-1/2 by 7-3/4 inches. The pins came 20 to a pack.

    Since the plate is ceramic, it is heat and flame-proof. I was able to use a propane mini-torch to do my soldering -- no issues. And the pins, being stainless steel, are also flame-proof. Better yet, ordinary solder won't stick to them. That can be very helpful when the soldering has to be done in tight quarters. But you should know that some special solders -- like Stay-Brite Silver Solder -- will bond to stainless steel. Then extra care may be required.

    The next photo shows an assembly I fixtured up for soldering using the ceramic plate and tapered pins. Should be self-explanatory.



    But there is another trick illustrated here. The center strip of brass (which is one inch wide and 1/16" thick) is wrapped in a piece of aluminum foil. Since it is not possible to solder to aluminum, the foil allowed me to use the central brass strip as a spacer without having to worry about it getting soldered into the assembly. In point of fact the thickness of the aluminum foil provided a few thousandths of clearance, so the assembly wouldn't bind when fitted to the one-inch-wide chassis it was designed for.

    The assembly was cleaned up. First with acetone, to remove the remaining flux. Then it was wire-brushed with a Dremel tool, to brighten everything up.

    Ed Bianchi
    Last edited by HO RacePro; 12-13-2018, 04:59 PM.

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  • HO RacePro
    replied
    Reacting to the excellent videos posted above...

    As I said at the beginning of this thread, there are bona fide experts on soldering, (and I am not one of them!) I'd not be at all surprised that some folks have gotten their PhD's doing research in soldering techniques.

    Look at soldering like auto maintenance. You can start at the shallow end -- analogous to checking the oil level and tire pressure -- and advance over time, with training and experience to the deep end -- analogous to engine and transmission repair. How deep you go is up to you, and you can advance at your own pace.

    Again, basic soldering is simple. You have to get a few things right -- metal, flux, heat and solder. Try it, prove to yourself that you can do the basics, and take it from there.

    Ed Bianchi

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  • ggmerino
    replied
    Here is a fine set of videos that dispel much of the bad info out there on the web: https://www.youtube.com/watch?v=vIT4...6EC0F1F93C1837

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  • HO RacePro
    replied
    For those new to soldering, EM's example of a soldered chassis joint is textbook. Beautiful fillet on the solder-application side with full penetration to the opposite side.

    As for Michael's comment about skills. Michael is right, core skills are key. But...

    Nobody is born with skills, they are developed over time with practice. There is no reason to be intimidated by examples of good work. Anybody who thinks, "Oh, I couldn't do that!", is probably selling themselves short.

    As I said at the beginning of this thread, soldering is a simple skill to learn. For most soldering the tools and supplies are cheap and readily available. Unlike many skills, soldering has an easy 'on ramp'. Strip two wires, twist them together, apply flux, heat and solder... BAM! You've made your first solder joint. You can now solder! From here on out its just a matter developing your skills through practice.

    Ed Bianchi

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  • Ecurie Martini
    replied
    It could be a DIY project - there are plans and articles out there often starting with a battery charger. The key is sourcing a transformer that is rugged enough.

    EM

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  • Jisp
    replied
    Thanks for the detailed replies guys. I now have an understanding of sorts, of whatís involved.

    Ed, thanks for an excellent thread. Episodes of lust concerning tools of any kind are the story of my life lol. I have many excellent tools but thereís always another just around the corner. As you say, itís a steep investment. Unfortunately the units are out of my reach for the very limited hobby soldering I do. If I produced and sold something that yielded a return on the investment it would be a different story. Doesnít hurt to lust though!

    EM, I confess I feel a little silly now thinking the unit was perhaps something that might be DIY constructed. Got carried away when you mentioned the carbon rod and foot peddle control. To me it sounded like a DIY unit. Thanks for the photos and in particular the labelled chassis image. Man, thatís some seriously nice soldering with the fruity benefit of keeping the heat local. If you have any other thoughts, tips, comments etc etc they'd be welcome.

    Good tools are desirable for many reasons but core skills at the hand are the roots. You guys are proof if itís required. Keep it coming!

    Cheers,
    Michael.

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  • Ecurie Martini
    replied
    In my experience, Micro Mark is a very expensive vendor. (their typical trick is to raise the listed prices just before a "sale") I use them when I cannot source my needs anywhere else.

    My set up was an eBay buy - used:





    http://www.lumaelectric.com/catalog/...1/solder-tools

    http://www.lumaelectric.com/catalog/...er-accessories

    The 3 binding posts provide different levels of maximum power when connected 1-2, 1-3, 2-3 and the rotary switch offers further adjustment. It does take some experimentation to determine the best power level

    Instructions: http://www.lumaelectric.com/source/manuals/551.pdf

    A joint in heavy (0.0625") brass:



    The electrode was applied to and drawn along the inside of the joint and solder applied to the outside. You can see that, in addition to forming a solder fillet on the outside, the solder was drawn through the joint to the inside.

    EM

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  • HO RacePro
    replied
    The one source I know for resistance soldering equipment is Micro-Mark:

    www.micromark.com

    From their website:

    Cheapest Set: https://www.micromark.com/Resistance-Soldering-Unit

    Value Set: https://www.micromark.com/Micro-Make...-Soldering-Set

    Most Expensive Set: https://www.micromark.com/250W-120v-...ezer-Handpiece

    Again, I have no experience with these tools. But I have had episodes of lust concerning them. I've been off-put by the investment required, but I strongly suspect, if I ever take the plunge, I'll regret not having done so sooner.

    With luck we'll have more input from folks who have experience with tools like these.

    Ed Bianchi

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  • Jisp
    replied
    EM, I'm a curious critter and am intrigued by your application of resistance soldering. Is the gear you use a commercial setup in a domestic environment or is it something that can be made with commonly available parts? Is there any chance of some photos of your setup please. Thanks for any additional info.

    Cheers,
    Michael.

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  • Ecurie Martini
    replied
    Originally posted by HO RacePro View Post
    I've heard about resistance soldering, but have no experience with it. Can someone contribute a post on it?

    Ed Bianchi
    A quick answer then I'll look for more info. It's rather like arc welding lite. The basis is a transformer with very low voltage high current secondary. There are two leads - often one ending in a clamp and the other a carbon electrode. The ground clamp is attached to the work and the electrode applied at the joint - a short circuit is created with intense heating at the point of application. It is very fast. Other tools are insulated tweezers with electrodes at the tip or pliers with a similar configuration.

    There are several advantages - very high temperatures are available - silver brazing is easily done. Because the area heats so quickly, the process can be completed before the heat has spread far from the joint - the heating is very precise. I use a carbon electrode and a foot switch to control power.

    EM

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