soldering

[delphParticipant @delph]

if your having trouble soldering, flux is vital. rather than dabbing wires in paste or liquid use “multicore” solder. available from various places its clean and easy to use. remember if your negative wire has gone black it will not solder and you need to cut it out. black wire syndrome is caused buy having battery’s connected but not turned on in a damp or cold room/garage. so for instance remove battery’s from transmitters when not in use.

Chris

[Richard SimpsonParticipant @richardsimpson88330]

The latest generations of no-clean fluxes are actually very good and, of course don’t need to be removed afterwards unless painting is to follow.  They can be applied with a brush during the soldering process.

Multicore though is still probably the easiest and most convenient for wire soldering.

I remember making a tin box when I was at school using a large copper soldering iron, heated up on a gas burner, and a big tin of Bakers Flux applied with a tatty brush!  Tell that to a teacher nowadays and they go a funny colour!  I’ve still got the box somewhere.

[bluetobitsParticipant @bluetobits]

I find “lead free” solder is really awful to work with. No amount of flux makes it easy and it must be very off putting for beginners. It’s getting harder to find the “full fat”  60/40 lead/tin alloy but its worth hunting out and paying the extra cost.  There’s some really dodgy cheap solder coming in from you know where, which is worth avoiding too.

[delphParticipant @delph]

yes, exactly. someone could easily be put off because of this poor solder. and as you say its not just wiring. I almost always solder my rudders to the rod, handrails etc.

Chris

[David Marks 2Participant @davidmarks2]

The important thing to remember with soldering is that the solder should be brought to melting point by the surface temperature of of the base/host material being soldered. So I tend to use a big iron but not of a wattage that will cause damage/distortion to the part being soldered.

Regarding Richard’s comment about school workshops. Yes, a lot of substances and techniques available to me during my mid teens at school would send many H&S personnel prematurely grey. However, providing the person has the correct training including using the correct PPE, all should be well.

[Richard SimpsonParticipant @richardsimpson88330]

I actually did three Boiler Room articles on soft soldering in March, April and May 2021 Editions of the magazine.  The one underlying key to success, as David rightly says, is that the job should melt the solder, not the heat source.

[Len Morris 2Participant @lenmorris2]

It’s all horses for courses and the job in hand.  With heavy well fitting new jobs heating the job first works well.  Best done with a furnace, blow lamp, gas torch etc.  With small jobs made of multiple smaller joints already soldered, you will not do well trying to heat the job up first.  It will probably all fall apart.  Heat transfers best via a liquid medium, in our case it’s molten solder.  I’ve found that even on a stone cold job establishing a puddle of solder at a soldering iron tip gets the heat in quickly at the point of focus.  Had excellent results even on 4mm brass plate.

The ‘lead free solders’ are horrible.  Too high a melting point, slushy and quite pointless for joining lead pipes and roof flashing etc.  The modern fluxes work but I choose to avoid them.  I use Fluxite and 60/40 solder bought on line.

Len

 

[Richard SimpsonParticipant @richardsimpson88330]

The bottom line is that, if the parent metal is not up to the melting point of the solder then the solder will simply pool on the surface.  The easiest way to ensure that the parent metal is at the melting point of the solder is to use the parent metal to heat the solder.  When the solder melts then you automatically know it will readily fuse to the parent metal.

While I agree that molten solder can be used to get that heat into the parent metal, and is a technique I use myself, especially when soldering wiring, the easiest way to teach someone new to soldering and to help them avoid the frustrations that too cool a parent metal can create, is to heat the solder with the parent metal.  Once they have mastered that technique they are better prepared to then go on to other techniques as described.

Going on to slightly more sophisticated techniques is going to be an easier path after a good understanding of the basics has been acheived.  Consequently while I disagree with the thought that smaller jobs made of multiple joints will probably fall apart, a sound understanding of the concept of heat transfer can help you acheive some quite complex small jobs as well as making you aware of what you shouldn’t try.  Using solders of different melting points is one technique but even the handrails shown here were all soft soldered in place by using the rails to heat the solder.  Every joint is soldered seperately and nothing fell apart.

Again a good understanding of the heat flow will help when soldering two metals of very different specific heat capacities and different heat flow rates such as a thick brass bush onto a very thin tin plate.  Again the best approach was to let the parent metal melt the solder as it would have been very difficult to get the temperature of the brass up without overheating the tin.  The entire brass bush needed to be at a consistent temperature to ensure an even fillet of solder was created all the way around the bush and capilliary action took the solder into the joint.

 

[Colin BishopModerator @colinbishop34627]

I am no expert in soldering and use it mainly for wiring. I have two irons, a 48 watt one on an inexpensive soldering station which has just packed up after 20 years or so (new one coming tomorrow) and an 85 watt one for he occasional metal to metal job when more heat is needed.

I do think it is worth mentioning one other method which nobody else I know seems to use. Handrails, as in Richard’s post above, are always a fiddly job and for these I have always found Carr’s solder paint to produce a neat result whether using pre drilled stanchions or just wire to wire joints. You do literally paint it on and apply heat to the wire adjacent to the joint and it melts around it to give a very neat result. I described this in my recent paddle steamer Bilsdale article and the image below shows it in progess. You can see how tidy the joints are and very little cleaning up is needed. In this case pre drilled brass stanchions were used but I have had equally successful results at smaller scales by making up a wooden jig off the model to hold the uprights and rails in place, solder painting the whole section and applying heat along it in one operation. The section is then removed from the jig and any excess snipped off and filed.

I’ve no idea how ultimately strong the joint is structurally, it’s certainly adequate for what I have done. But, as Len says, it’s horses for courses, and the solder paint is excellent for delicate built up constructions.

Colin

[Len Morris 2Participant @lenmorris2]

Whatever, I bow to all your expert opinions.

Len

[Colin BishopModerator @colinbishop34627]

We are not experts Len, just pragmatists sharing experience! Take your pick!

Colin

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