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Resistance Soldering


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Hi there

Just about to set off into the world of resistance soldering and was wondering what to use for solder when soldering smaller parts such as wagon strapping or detailing? 
I see such things as solder paste, cream or paint and wonder if these are suitable and what those experienced in this area would recommend?

many thanks 

 

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I would recommend Carr's 188 solder paste. You can get similar products more cheaply from China but my experience is that they dry out rather quickly and do not perform as well.  Small amounts can be easily applied with little or no cleaning up afterward.

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You can tin overlays and then use the RSU to attach them. Solder paste works just as well, you hardly need any at all to attach items. Like pretty much anything, there are many ways to do things and no one way is "the best". Use the most suitable for the situation.

 

For the Siphon kit I'm currently building I have used both tinning and paste. Tinning on the main folds in the 1st pic and the corner strapping and door hinges in the 2nd pic used paste. I'm using the cheap China stuff, it's easy to reactivate with flux if it dries out a bit.

 

RSU3.JPG.a05d3b341dd51365d75a51af668d25a8.JPG1476060725_SiphonCcloseup.jpg.4d470bbc781892e697af637fe615009e.jpg

Edited by 57xx
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I used to use the Carrs paste when I started, but I now just tin items with standard flux and solder.

Find what works for you and stick with it.

 

Also don’t be fixed on the metal plate, I just use an alligator clip as it allows me to turn items easily.

Never caused any problems and less to clean and clutter up the bench.

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16 hours ago, EKR said:

I used to use the Carrs paste when I started, but I now just tin items with standard flux and solder.

Find what works for you and stick with it.

 

Both work, have their place and can be used side by side, no need to be fixated on one or the other.

 

16 hours ago, EKR said:

Also don’t be fixed on the metal plate, I just use an alligator clip as it allows me to turn items easily.

Never caused any problems and less to clean and clutter up the bench.

 

I use both the plate and alligator clips, all depends on what I'm soldering. Some small parts are just not suited to using the clip so the plate comes in very handy. A larger assembly that can take the clip gives a better return to ground, but again it's not a case of you have to use only one or the other. Use the best tool for the task in hand and don't limit your options.

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On 06/07/2020 at 23:23, dpgibbons said:

The steel baseplate also gives you the very valuable option of holding parts in alignment using magnets.

 

Shamelessly stolen from another thread, this video shows why 'gator clips are not always the best way to hold things and also gives many examples of how not to use an RSU!

 

 

Edited by 57xx
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22 minutes ago, Martinnj said:

Thanks for the above advice, much appreciated, now to try and put something together! Probably start with a London Road Models LBSCR 4 wheeled luggage van to start....

 

 

I'd personally start with some scraps of brass to get used to the concept first, then move on to a kit.

 

Mike.

 

 

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5 hours ago, Bucoops said:

I'm awaiting delivery of an RSU so this has been very helpful! Normally you learn the wrong way first, but it's nice of someone to show me the wrong way first :D

Can I ask which RSU you are getting.

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2 hours ago, Bucoops said:

 

London Road Models :)

 

https://traders.scalefour.org/LondonRoadModels/various/soldering-materials-and-tools/

 

There's a waiting list but I understand there should be another batch in about 6 weeks.

Had mine for well over 25 years. When finally, I killed it ( usually set at "11") they took it back and rebuilt it for less than half the cost of a new one.

One tip for crocodile clips ( the size found on battery chargers), I ground off the teeth on one side avoiding aforementioned problems. It is worth getting a spare earth cable which can be soldered to an earth plate.

The thing is to discover what it can do, and more importantly, what it doesn't do well. It hasn't replaced my traditional soldering iron, it complements it. Well "them" as there are at least four on the ready to go rack. 

I won't try and compete with the experts but my three reasons for not wanting to be without it: 

Jobs can be tacked together with small blobs of solder from an iron when all is square and true the RSU completes the seam.

With practice, the roof on a tank engine can be added after painting.

They are great for dismantling a job gone wrong or rebuilding someone else's work.

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41 minutes ago, doilum said:

Had mine for well over 25 years. When finally, I killed it ( usually set at "11") they took it back and rebuilt it for less than half the cost of a new one.

One tip for crocodile clips ( the size found on battery chargers), I ground off the teeth on one side avoiding aforementioned problems. It is worth getting a spare earth cable which can be soldered to an earth plate.

The thing is to discover what it can do, and more importantly, what it doesn't do well. It hasn't replaced my traditional soldering iron, it complements it. Well "them" as there are at least four on the ready to go rack. 

I won't try and compete with the experts but my three reasons for not wanting to be without it: 

Jobs can be tacked together with small blobs of solder from an iron when all is square and true the RSU completes the seam.

With practice, the roof on a tank engine can be added after painting.

They are great for dismantling a job gone wrong or rebuilding someone else's work.

 

Great info - thanks :)

 

What's the method when dismantling pieces please? I have to do that a lot :D

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1 hour ago, Bucoops said:

 

Great info - thanks :)

 

What's the method when dismantling pieces please? I have to do that a lot :D

Clean off paint for a good earth and contact area.

Power at max

Have tweezers and scalpel with an old blade to hand.

The instant heat does its job, the tools separate the parts.

Clean up and start again!

Forgot to add: the Dremel is good for cleaning up!

Edited by doilum
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  • 2 weeks later...

Missed some of the chat, but want to say that if your using enough power to burn clip marks into the metal, the damage at the probe end would be much much worse. 

Frankly I’ve never done it.

But then my standard setting is low power. Only boosted when needed.

After you’ve managed to melt your first couple of handrail knobs you learn to use some delicacy...

 

I did start following Raymond Walley’s advice, but rapidly ditched the plate and magnets. Just more to clean and get lost on my messy workbench. The magnets are quickly replaced with clips, pins and bluetack on a flat surface. Pretty much what I use with my regular iron.

 

It’s worth repeating that the rsu is a great problem solver, as it gives the ability to push with the probe much more cleanly than with a regular iron.

Something not fixed correctly? Push it off with the probe. A hand rail a fraction out of line? Just nudge it with the probe.

The cabside fractionally unaligned at the top? Again nudge with the probe.

Like any tool, the more you use it, the more uses you’ll find for it.

 

 

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4 hours ago, EKR said:

Missed some of the chat, but want to say that if your using enough power to burn clip marks into the metal, the damage at the probe end would be much much worse. 

Frankly I’ve never done it.

But then my standard setting is low power. Only boosted when needed.

After you’ve managed to melt your first couple of handrail knobs you learn to use some delicacy...

 

It is worth practising with scrap etch before committing yourself and the RSU to the kit.  Until you have built up experience, I recommend always starting with a lower setting and working up.  Working in 4mm, my LRM unit is on 2 volts for a majority of the work but I reduce it to 1.5 volts when soldering brass or nickel silver to white metal.

 

I have never got on with paste as I find it spits, so I either tin bits first, 145 or 183 degree solder, or cut small pieces to reinforce folds, where I flux the fold, add a bit of solder then apply the probe to the outside of the fold.  When the solder melts (it can jump off if you boil the flux behind the solder, so apply the probe slightly to one side), it flashes along the fold and you can draw it along a bit further by sliding the probe so that the solder follows the heat.

 

Do not think the RSU will solve all your soldering problems - it won't, nor will it replace your conventional iron.  It has its good points but there are also times when it is not as good as a conventional iron.  The knack is knowing when to use the right tool!

 

I wrote a couple of articles for Scalefour news a couple of years ago which people told me they found useful, so I will attach a copy here in the hope that it will contribute to people's use of the technique.

Spirit of Resistance (opt).pdf

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I should have added to the previous post that burn marks can happen if the tip of the probe gets dirty.  A dirty tip also reduces the efficiency.  Every so often, give it a wipe or better still, clean it with a bit of abrasive paper or a file.

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On 13/07/2020 at 04:49, Bucoops said:

Had mine for well over 25 years. When finally, I killed it ( usually set at "11") they took it back and rebuilt it for less than half the cost of a new one.

 

Sounds like you had a lot of resistance in your RSU circuit. In that respect a baseplate is much better than clips, although you then need to offset the heatsink effects with insulating measures like the use of paper as mentioned above.

Edited by dpgibbons
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7 hours ago, dpgibbons said:

 

Sounds like you had a lot of resistance in your RSU circuit. In that respect a baseplate is much better than clips, although you then need to offset the heatsink effects with insulating measures like the use of paper as mentioned above.

 

Not sure how you managed to make that quote look like it came from me :D

 

I've got mine but not tried it yet. I'm making a metal plate thingy but not found a suitable bit of wood to mount it to yet.

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