Kitbashed Resistance Soldering- Ideal for N scale

[u18b]

Hi.
I decided to move the discussion from the New EP-2 thread
https://www.therailwire.net/forum/index.php?topic=31042.0

Since this is really a new topic (worthy of searching and archiving in the future).

Eventually, the mods will want to move this, but maybe it can stay for a little.
I trust their good judgement.

I started by.....
----------------------------------------------------------

I finished building a Resistance Soldering Station.



It was much more involved a project than I thought.  Not the device, but all the photography, and thinking, and writing.  It is 31 pages- which sounds like a lot, but my hope is that it is VERY clear.  Magazines just can't do something like this.

So download away.  And enjoy.  I'd love to know if you build one and it works.  I can already see that this will be a very valuable tool in the future.  I've already used it to repair one of my damaged brass locomotives.

http://u18b.com/wp-content/uploads/2013/03/ResisSolder1403.pdf

I tried VERY hard to keep the size under 1 meg so as to reduce my bandwidth hit from my website.

[u18b]

Max said:

Downloaded it.
Read it.

FABULOUS!

Ron, the things I always wondered about with home-building one of these were:
1. Where to get carbon electrodes?   People get them out of the inside of carbon batteries and such, but
that always seemed like a royal pain, and they are so thick.  I'm surprised that the mechanical pencil
leads work.  I didn't think they really had that much carbon in them.  But that's great!

2. What to use for a power supply?  I mean, I'm not afraid to build one.  But I had no idea what voltage and current
I really wanted to shoot for.  A PC switching supply.   Ha!  You can get those anywhere and CHEAP, as you point out.

QUESTION:
Do you have any idea how many amps your probe is really drawing?  Did you by any chance stick an ammeter in
there and see if it's drawing 5 amps, 12 amps, whatever?   Your supply is rated for 22A at 5V, so you're not drawing
more than that.  But I've always been curious about how much power really you really need to make one of these work.

And one more question... how finicky are those pencil leads when you make a joint?  I would have thought they would
break off very easily and be a nuisance.

Loved your paper.

[u18b]

Mike said....

Nice Ron.  My only comment would be that the American Beauty Ni-Chrome electrodes are extremely cheap.  With a much longer life and strength than the pencil lead, I think they would still qualify for your budget build at just over $10:

https://www.americanbeautytools.com/site/Resistance-Soldering/152

[u18b]

I responded with...

Thanks Max,

I'm with you.  I see that many people consider AA or AAA batteries as a source for carbon electrodes.
Who knows, maybe there's nothing to it... but I just don't want to deal with acid or a mess.

As for mechanical pencils, I'm sure there are differences as to carbon content.  My paper shows differences between two brands.  I might have just had dumb luck that one of the brands was high quality in the carbon department.

As to workability of the micro-electrodes I'm using.  Yes, they are a bit delicate.  But they are also cheap cheap cheap.

You have to remember, this is a different kind of soldering.  In regular soldering, the heat is transferred by touch.  The more surface area of the tip that touches, the more heat is transferred.  I know that when I'm trying to UN-solder something from a PC-board, I often press down pretty hard-- trying to transfer as much heat as possible to get that part loose.

This system works in an entirely different way.  Pressure has zero effect on heat.  Heat is only created by one thing-- electricity flow.  So you have to train your brain to be very delicate with these electrodes.  Let the electricity do the work.  So in answer to your question, once your brain is trained to touch and not press, I found I broke very few electrode-- until they get very thin that is.

I have never hand laid track, so I am wondering if this setup would be ideal for that application.

As to actual amperage, no it did not occur to me.  When I get a chance, I will see what I can find out.

As I say in the book, it did not work (first try) with 12 volts.  If the resistance is the same, then V= IR...... V/I = R.  So if the voltage goes up by almost a factor of 3, then the amperage should go down by about 1/3 (if I understand the math).  So I'm not sure why it didn't work.

But I will report back when I have a chance to measure the amperage.

[u18b]

And finally...... (this catches us up)....


Mike, thanks for the suggestion.

I'm wondering if the product by MicroMark is similar.
http://www.micromark.com/extra-tips-for-needlepoint-electrodes-set-of-2,8240.html

They are a fraction cheaper.

[mmagliaro]

Ron,

Regarding this:
As to actual amperage, no it did not occur to me.  When I get a chance, I will see what I can find out.

As I say in the book, it did not work (first try) with 12 volts.  If the resistance is the same, then V= IR...... V/I = R.  So if the voltage goes up by almost a factor of 3, then the amperage should go down by about 1/3 (if I understand the math).  So I'm not sure why it didn't work.


This isn't correct.

The resistance is the same.   
and yes, V = IR
If you raise the voltage by a factor of 3, the current goes UP by a factor of 3.  It does not stay the same.
Or, the way you wrote it:
V/I = R   Again, if V goes up by 3x, then I has to rise by 3x in order for R to be constant, which it is.

If you are drawing 12 amps at 5v, then at 12v you will draw 12/5 x 12 = about 30 amps!

[u18b]

Thanks Max.  I knew my (5th grade) math had to be wrong.
I could blame it on having a bad cold... haha.

Anyway, at 3 times the amperage, that would be why the unit shuts down at 12 volts.

I got home and quickly checked my multimeter.  Amps is something I don't check very often (I probably should do more of it).

At any rate, my multimeter only goes to 10 amps.  In this unique case, I'd be afraid of using it since I'm reasonably sure we are over that.  I wouldn't want to risk damage.


On a different topic, another safety feature of computer power supplies is a guess.  But there is a slender part, almost like a tantalum capacitor in shape bolted to the huge heat sink.  I'd bet anything that this is a thermister which means not only is the unit voltage/amperage protected, but it is also protected from overheating.

[u18b]

Another thing that I will mention in the second release of this work is....

Ground is ground..... no matter how you get there.

Well, in the situation of this device, the steel box is grounded.

So when you LAY something metal on top of it.... you are grounded.  You don't need the alligator clip.

So I have already started to use the box as a working surface.

Like in that lead photo.



I guess the only caution is that you want to make sure no excess solder droplets or metal falls into the machine.

[Ike the BN Freak]

Saw another DIY on this not too long ago, they used a car battery charger for the power supply.  Thought of putting one together for myself sometime in the near future.

[Lemosteam]

Me-wannie!!  Gonna makie!  Thank Ron, i have been wanting a resistance iron for many moons.

There are also  1/8" diameter pencil leads that can be sharpened with a drafting sharpener with a fairly long taper. 

http://www.dickblick.com/products/staedtler-leads/?clickTracking=true&wmcp=pla&wmcid=items&wmckw=22828-2052&CAWELAID=520010530000018275&gclid=CI--q-HYkr0CFWEV7AodolEAtA

They also mechanical come in harder grades too, not sure the carbon content 4h is hard as a rock. 

I still remember the pre CAD drafing days, ahh the joy.

The company may be willing to provide a material breakdown.

[u18b]

Did a little research on Pencils.

Wiki says pencils are made of a mixture of Graphite (carbon) and clay (that would be the polymers equivalent.)

So the more Hs (hardness) then the more polymers or clay is added to stiffen it up.

The more Bs (for blackness) it is rated, the more carbon content, I assume.

So using Lemo's link....
http://www.dickblick.com/products/staedtler-leads/?clickTracking=true&wmcp=pla&wmcid=items&wmckw=22828-2052&CAWELAID=520010530000018275&gclid=CI--q-HYkr0CFWEV7AodolEAtA

I see that 2B and 4B might be the best for electrode use.

[C855B]

Did a little research on Pencils.
...I see that 2B and 4B might be the best for electrode use.

Hmm. 2B, or not 2B. That is the question.

4B, depending on thickness, will likely be too soft and collapse under the pressure of pushing against the workpiece. At least that was my experience in drafting class.

[up1950s]

I have an American Beauty 105-a3 100 watt setup for over 2 years and over 10 brass kits to use it on . I haven't yet plugged it in . 

[chicken45]

[reinhardtjh]

I just bought a used American Beauty 250w system on Ebay for $280.  I coulda bought an M1a and built this!