Resisdence soldering or normal soldering whats the difference?

[JeffP]

Just to add, and this may be relevant for those already in possession of an RSU, I have found a source of quite cheap carbon probes.

 

At Kettering earlier this year, my eldest, a welder and plater by trade, now at uni studying Mech Eng., was with me, and picked up a set of carbon rods for the RSU off one stall, asking me what they were for.

 

Reason he asked is that he saw them as "Carbon arc gouging rods", and wondered how they were used in modelling.

 

If you want some, search "Buy carbon arc gouging rods 5mm", or variations, in Google. I have found them at £20 a box of 100 and £0.09 p each. Don't foregt 5mm, they come in sizes from 3mm up to about 20mm diameter and are 300mm long. The 5mm ones fit the LRM holder.

 

If you have a different RSU, measure one of your rods, then search for that diameter....they also come in imperial sizes.

[PGC]

My dad taught me how to solder at the age of about 6 with a 50 watt iron and a 1/4 inch bit without problems. I now have an arsenal of irons an 80 watt, a 25 watt, a 40 watt temp control, a 12 volt unknown wattage, used with a variable transormer, for white metal and the RSU and my favourite by far is the RSU. By the way I'm nearly sixty now.

My Dad taught me how to solder with an ex GPO soldering iron that you had to keep in the gas ring until it got to the right temperature. Once I'd got the knack of judging the different shades of red hot, I felt as though I could solder just about anything, until I tried white metal!!!

 

Nowadays, like you, I have an variety of irons and an RSU, and the luxury of a work bench where I can keep them all lined up, ready for action, like toy soldiers. I've even named them - David, Ed, Nick, Nigel -the names are purely chosen as they all produce heat!!!! 

 

Phil

[Earl Bathurst]

So if I bought a rsu what else would I need to buy apart from the solder paste?

[Adrian]

 

If you want some, search "Buy carbon arc gouging rods 5mm", or variations, in Google. I have found them at £20 a box of 100 and £0.09 p each. Don't foregt 5mm, they come in sizes from 3mm up to about 20mm diameter and are 300mm long. The 5mm ones fit the LRM holder.

 

 

I didn't need to buy any - just went to my local welding supply shop and they had plenty of scrap rods ends which they let me have for free. 

[Siberian Snooper]

So if I bought a rsu what else would I need to buy apart from the solder paste?

 

Carbon rods to suit your probe, see JeffP's post above. plus a fibreglass pencil to clean the brass/nickel silver before soldering, if you don't have one already. CIF and an old tooth brush to clean up after.

[TheWeatheringMan]

No, I noticed your RSU has a label saying Live/Arc, so I assumed that's what you do with it.

Hi,

Fair comment.

As you will have quessed I designed the front panel myself and simply labelled the red sockets thus as the carbon probe does form an arc when used in a cirtain way - I have several different carbon designs and thicknesses available and using the thinest (1.5mm) diameter with a very sharp point and the RSU on full power ('full/high' on the switches) I can in fact spot weld things like chassis frames to spacers to hold them while the full seam is completed after checking for squareness etc.

My post was intended as a joke to Chris as to how to use an RSU on one of his resin locos.

 

Regards

[TheWeatheringMan]

Just to add, and this may be relevant for those already in possession of an RSU, I have found a source of quite cheap carbon probes.

 

At Kettering earlier this year, my eldest, a welder and plater by trade, now at uni studying Mech Eng., was with me, and picked up a set of carbon rods for the RSU off one stall, asking me what they were for.

 

Reason he asked is that he saw them as "Carbon arc gouging rods", and wondered how they were used in modelling.

 

If you want some, search "Buy carbon arc gouging rods 5mm", or variations, in Google. I have found them at £20 a box of 100 and £0.09 p each. Don't foregt 5mm, they come in sizes from 3mm up to about 20mm diameter and are 300mm long. The 5mm ones fit the LRM holder.

 

If you have a different RSU, measure one of your rods, then search for that diameter....they also come in imperial sizes.

Hi,

A very usefull post for many users and indeed the very thing I did in order to stock up a couple of years ago.

Points can be formed on the rods with a cheap desk pencil shapener - although most such sharpeners will not allow rod lengths much below 2 1/2 inches due to the working of the mechanism - although its easy enough to sharpen the carbon rod first and then saw off any excess length from the other end.

 

Incidently most commercial rods are copper coated.

Now while that is good it is not essential so another source of rods of various diameters is the carbon rod in the centre of Zinc Carbon batteries.

Dismantle the battery, clean the rod and allow to dry, sharpen it to a point and bobs your uncle.

Works perfectly but remember that Alkalyne batteries do not contain a carbon rod so dont dismantle one of them.

 

Even if you have to buy a pack of ZC batteries from one pound shop to break up its still a very ecconomic way to source rods for an RSU.

 

Regards

[Graham Hughes]

Unless I'm wrong (it's possible!) this statement is not accurate, The factor that determines how much heat is put in to the joint is the wattage of the iron.

 

Going back to basics, every action has an opposite and equal reaction. So when you put a hot iron to a cold piece of metal, the cold piece of metal starts to warm up while the hot iron starts to cool down. The more wattage the iron has, the more possibility it has of keeping warm rather than cooling down.

No the statement is accurate. The keyword is "quickly". I was not referring to the total quantity of heat applied but to the rate of heat transfer. Of rather more relevance than Newton's Third Law of Motion is Fourier's Law of Heat Conduction which tells us that the quantity of heat flow is proportionate to the cross sectional area of the material, the co-efficient of thermal conductivity of the material and the temperature differential.

 

As Jol says (albeit I understand he was also taking issue with my comment.) "Higher temperature only helps as it provides a small reservoir of heat but once the temp drops when the bit is applied to the work, it is power (watts) that maintains it. More watts, more ability to sustain the temperature." Well yes, that is exactly the point. If we are soldering a joint on a part built model or adding fine details (the stated advantage of an RSU) we don't want to sustain the temperature and thus the rate of heat flow. The last thing we want is to heat the whole thing up so bits start falling off elsewhere, we want to apply a small quantity of localised heat quickly not a sustained application of heat over a longer period. That "small reservoir of heat" is just what we need.The whole point of the iron is to supply heat. Something that is going to reduce its ability to do this is counter-productive. Furthermore, as the tip temperature is going to drop anyway as soon as we apply the tip to the joint it is hard to see the advantage of reducing that temperature to start with.

 

I wasn't intending getting into the physics of heat transfer, (and I will forgo getting embroiled in the chemistry of the oxidisation of metals due to heat  except to say the black stuff on the tip is far more likely to be because the flux has burned than the solder has been heated to the temperatures needed to oxidise its components.) It was a genuine question about why Jol recommended "preferably a temperature controlled iron" as my own, not inconsiderable, experience has led me to conclude it is not something which offers me any real advantage for building models. The only exception to this would be if you aren't confident in your abilities to solder white metal and want the safeguard of knowing the tip is at a lower temperature than the melting point of the metal. As I said I have the Antex TC50 which has seen at least thirty years use including a considerable portion of that time making patterns for 2mm and 3mm kits and castings as well as scratch-building models in those scales for my own enjoyment. If I was replacing it I would buy another one the same but if Antex made a similar 50W iron without the temperature adjustment I would buy that in preference. I was more interested in hearing Jol's differing point of view than starting a debate.

[Jol Wilkinson]

If you buy "gouging rods" with a copper coating in bulk, check the surface finish. It can be quite "rough" and need polishing to make a good fit in the probe. 

[Graham Hughes]

My Dad taught me how to solder with an ex GPO soldering iron that you had to keep in the gas ring until it got to the right temperature. Once I'd got the knack of judging the different shades of red hot, I felt as though I could solder just about anything, until I tried white metal!!!

 

 

Amateur. I built an ABS/Beaver J63 in N gauge with one of those. (OK not very well and it was a bit melted at one side) We had a whole range of those irons from the tiny little one I used for the kit to a giant one that would have felled an elephant. Legacy of my grandfather's job as a colliery fitter. 

[Enterprisingwestern]

addendum : Just look at what the 2mmFS people are doing - that's some damn fine detailing with little excess solder - all done with a normal iron.

Click on the photo's to enlarge - very impressive. So this is why I say I struggle to see the advantage of an RSU as I don't think it could do it any better than this.

http://www.rmweb.co.uk/community/index.php?/blog/1004/entry-8277-2mm-scale-lnwr-diagram-88-van-building-the-van-body/

 

But thats nothing to do with the iron, that's the operator. Give me a paintbrush and paints, and I couldnt emulate Turner/Constable et al.

 

Mike.

[TheWeatheringMan]

If you buy "gouging rods" with a copper coating in bulk, check the surface finish. It can be quite "rough" and need polishing to make a good fit in the probe. 

Hi,

A very good point that i'd overlooked totally.

When I bought my stock the 5mm rods varied considerably - some were smooth and well polished but many were rough enough to remove the 'flash' from a whitemetal footplate with.

Perhaps the only problem with buying them online is that they are mostly sold in a batch so its almost impossible to be sure how good the finish will be in advance - this, unfortunatley, is what happened to me, but as you say a gentle rub with some fine wet and dry should sort it out.

Nevertheless, a good warning that will help others.

Many Thanks.

 

Regards

[Jol Wilkinson]

No the statement is accurate. The keyword is "quickly". I was not referring to the total quantity of heat applied but to the rate of heat transfer. Of rather more relevance than Newton's Third Law of Motion is Fourier's Law of Heat Conduction which tells us that the quantity of heat flow is proportionate to the cross sectional area of the material, the co-efficient of thermal conductivity of the material and the temperature differential.

 

As Jol says (albeit I understand he was also taking issue with my comment.) "Higher temperature only helps as it provides a small reservoir of heat but once the temp drops when the bit is applied to the work, it is power (watts) that maintains it. More watts, more ability to sustain the temperature." Well yes, that is exactly the point. If we are soldering a joint on a part built model or adding fine details (the stated advantage of an RSU) we don't want to sustain the temperature and thus the rate of heat flow. The last thing we want is to heat the whole thing up so bits start falling off elsewhere, we want to apply a small quantity of localised heat quickly not a sustained application of heat over a longer period. That "small reservoir of heat" is just what we need.The whole point of the iron is to supply heat. Something that is going to reduce its ability to do this is counter-productive. Furthermore, as the tip temperature is going to drop anyway as soon as we apply the tip to the joint it is hard to see the advantage of reducing that temperature to start with.

 

I wasn't intending getting into the physics of heat transfer, (and I will forgo getting embroiled in the chemistry of the oxidisation of metals due to heat  except to say the black stuff on the tip is far more likely to be because the flux has burned than the solder has been heated to the temperatures needed to oxidise its components.) It was a genuine question about why Jol recommended "preferably a temperature controlled iron" as my own, not inconsiderable, experience has led me to conclude it is not something which offers me any real advantage for building models. The only exception to this would be if you aren't confident in your abilities to solder white metal and want the safeguard of knowing the tip is at a lower temperature than the melting point of the metal. As I said I have the Antex TC50 which has seen at least thirty years use including a considerable portion of that time making patterns for 2mm and 3mm kits and castings as well as scratch-building models in those scales for my own enjoyment. If I was replacing it I would buy another one the same but if Antex made a similar 50W iron without the temperature adjustment I would buy that in preference. I was more interested in hearing Jol's differing point of view than starting a debate.

Hi Graham,

 

the point I was trying to make is that with a TC iron you can apply sufficient heat at the right temperature to create the solder joint quickly. The only way you can control the heat "feed" with an ordinary iron is by changing the bit for one with a smaller or larger cross section.

 

I wasn't trying to take issue with you, simply explaining things as I see them.

 

Whichever approach you use, I find that my Antex 50watt TCU gives me better results than I can get with their standard 25 watt iron, possibly  what most modellers use. Of course, we could all follow the late George Norton's approach and use a Solon 80 watt (IIRC) iron with a huge chisel bit. In and out fast was the order of the day, but he did build some lovely models. When and if my Antex claps out, I'll probably look for something similar to it but with even more "grunt"

 

Jol

 

p.s. I thing soldering topics probably create almost as much "debate" as using P4 standards, witness the recent MRJ 264 "Flangegate " discussions, although this thread still has some way to go to catch up.

[TheWeatheringMan]

Hi Graham,

 

the point I was trying to make is that with a TC iron you can apply sufficient heat at the right temperature to create the solder joint quickly. The only way you can control the heat "feed" with an ordinary iron is by changing the bit for one with a smaller or larger cross section.

 

I wasn't trying to take issue with you, simply explaining things as I see them.

 

Whichever approach you use, I find that my Antex 50watt TCU gives me better results than I can get with their standard 25 watt iron, possibly  what most modellers use. Of course, we could all follow the late George Norton's approach and use a Solon 80 watt (IIRC) iron with a huge chisel bit. In and out fast was the order of the day, but he did build some lovely models. When and if my Antex claps out, I'll probably look for something similar to it but with even more "grunt"

 

Jol

 

p.s. I thing soldering topics probably create almost as much "debate" as using P4 standards, witness the recent MRJ 264 "Flangegate " discussions, although this thread still has some way to go to catch up.

Hi,

In a situation where it is necessary to reduce the temperature of a non controlled iron there is a 'trick' that can be used that was described years ago by one on the accepted experts of the time although I cant remember for certain who - my mind suggests it might have been either Guy Williams or perhaps even John Ahern earlier still in one of his books - i'll need to go through the books in my library to find out for sure who it was.

The 'trick' is to wind thick copper wire from an electricity cable round the bit, staying clear of the working area of course, and allowing a length to stick out, perhaps even two legths.

The principle was that the wire would conduct the heat away from the bit and then radiate the heat into the air.

Although the element will try to work harder to replace the lost heat the describer of the 'trick' made it clear that this did work.

 

That said, your advice regarding a TC iron is obviously the more reliable way to go and i'd back up your advice totally.

 

Regards

[Graham Hughes]

Hi Graham,

 

the point I was trying to make is that with a TC iron you can apply sufficient heat at the right temperature to create the solder joint quickly. The only way you can control the heat "feed" with an ordinary iron is by changing the bit for one with a smaller or larger cross section.

 

I wasn't trying to take issue with you, simply explaining things as I see them.

 

Whichever approach you use, I find that my Antex 50watt TCU gives me better results than I can get with their standard 25 watt iron, possibly  what most modellers use. Of course, we could all follow the late George Norton's approach and use a Solon 80 watt (IIRC) iron with a huge chisel bit. In and out fast was the order of the day, but he did build some lovely models. When and if my Antex claps out, I'll probably look for something similar to it but with even more "grunt"

 

Jol

 

p.s. I thing soldering topics probably create almost as much "debate" as using P4 standards, witness the recent MRJ 264 "Flangegate " discussions, although this thread still has some way to go to catch up.

 

I think my approach to soldering is probably very similar to George Norton's. He sounds like a man who knew how to solder. I never met him but did build some reductions of his excellent 7mm kits. The instructions for the 3mm version of the J-25, I think it was, (not written by Mr. Norton himself) said to throw most of the detail bits away as they were too small to use in 3mm but I went ahead and used them anyway. It was a lovely kit to build and made a lovely model once I had replaced the dreadful castings, (again nothing to do with Mr. Norton.) I think maybe my 50W Antex is more than equivalent, in the scales I work in, to 80W in 7mm and I still have some of the small bits that I bought with it, unused in their packaging, but have lost count of the number of 4.7mm and 6.0mm bits I have gone through. 

 

At least you said soldering threads create "debate" and not "heat".  Admit it, you were tempted. I thought there was an interesting discussion to be had on the MRJ 234 thread if you could follow it through all the "here the P4 modellers go again" posts. 

[Adrian]

But thats nothing to do with the iron, that's the operator. Give me a paintbrush and paints, and I couldnt emulate Turner/Constable et al.

 

Mike.

 

Which is exactly my point - to continue your analogy if people started eulogising about airbrushes making it so much easier to paint and you went out and bought an airbrush but you still won't be able to paint like Turner/Constable.

 

I'm just raising a note of caution for people considering buying an RSU that it isn't a panacea for soldering small details. Yes I accept that some people find an RSU a boon yet others manage with a traditional iron. It's how you use the tools you have and getting an RSU doesn't automatically enable you to solder small details. So I would recommend that anyone contemplating one to go to a club or show first to see if they can practice with one before shelling out a lot of money.

[Adrian]

What's the problem? My workplate sits alongside my formica covered worksurface, the RSU and TCU sit side by side at the back on the bench, with the iron and probe in soldering iron rests. The footswitch is on the floor under the bench. Of course I am fortunate to have a permanent workbench, but even when I didn't I used to set up things so that the toolsI needed were to hand. 

 

 

I never said it was a problem, I too have a permanent workbench but I also have a pendant drill with a footswitch as well and having to find a clear area to put the earth plate was challenging. So it wasn't a problem it was just more convenient and easier to use the standard iron rather than the RSU.

[PGC]

So if I bought a rsu what else would I need to buy apart from the solder paste?

 

EB - Assuming you're starting from scratch, first things first. Buy a decent conventional soldering iron (a 25 Watt Antex XS is a very good beginners iron and not overly expensive), together with flux and solder. Personally I use 12% phosphoric acid flux and 145 degree solder, but what you use is down to what you find gives you best results. Some people use jelly type flux like Frys Powerflow - personally, I can't stand the stuff!

 

Once you've got to grips with conventional soldering, buy an RSU (my personal recommendation would be the LRM one, but that's purely because I have one and know it does the job) and possibly some solder cream or paste. Again, personally, I don't worry with solder cream or paste - I make sure both parts to be soldered with the RSU are tinned with a very small amount of solder using the conventional iron, then I flux the parts and hold them together using the probes of the RSU. Once I'm happy with the positioning of the components, I then step on the footswitch of the RSU, let the heat do it's stuff to the solder, take my foot of the switch and I'm a happy man.

 

Hope that is of help and gives some answers to your question.

 

I never said it was a problem, I too have a permanent workbench but I also have a pendant drill with a footswitch as well and having to find a clear area to put the earth plate was challenging. So it wasn't a problem it was just more convenient and easier to use the standard iron rather than the RSU.

 

More proof - it's horses for courses.

 

Phil

[Graham Hughes]

 I make sure both parts to be soldered with the RSU are tinned with a very small amount of solder using the conventional iron, then I flux the parts and hold them together using the probes of the RSU. Once I'm happy with the positioning of the components, I then step on the footswitch of the RSU, let the heat do it's stuff to the solder, take my foot of the switch and I'm a happy man.

 

Maybe I am not seeing something obvious but given that this is exactly what you would do with a conventional iron I am still nonplussed as to what the advantage is of applying the heat with an RSU rather than the iron, especially since you use the iron anyway to tin the parts

[chrisf]

As others have said, an RSU is pretty good for adding fine detail without melting what is already there.  I find also [should have said so in my earlier post] that I use less solder with the RSU and so there is less cleaning up to do.

 

PGC's advice above is sound and not just because it is exactly what I did!  There is usually more than one way of reaching the same result.  My soldering tuition was with a 25W Antex and very good it is too but one is never too old to learn and having seen others wield an RSU and obtain excellent results I decided to obtain one for myself.  Having done so, as I said earlier in this thread, I have chosen to see just what it will do for the reason given above.  

 

BTW, Graham, if you use solder paste you can use an RSU for tinning.

 

Chris

[PGC]

Maybe I am not seeing something obvious but given that this is exactly what you would do with a conventional iron I am still nonplussed as to what the advantage is of applying the heat with an RSU rather than the iron, especially since you use the iron anyway to tin the parts

 

As Chrisf says, you can use an RSU with solder paste or solder cream, should you wish, and you then don't need to tin the parts. It's just my personal way of doing things, and I don't need to spend money on solder paste or cream if I don't need to. The main advantage of an RSU is that you don't apply heat until you need to, so other closely soldered components don't come detached, and it's easy to get the small details exactly in position without burning fingers etc.

 

Phil

[JeffP]

It's how the highly detailed far eastern brass models are made.

[raymw]

For my home made rsu (mentioned here http://www.rmweb.co.uk/community/index.php?/topic/93228-soldering-irons-solder-fluxes-techniques/page-2&do=findComment&comment=1689872 ) I use a 'normal' welding rod tool holder. I added a small push button and LED. This avoids finding a clear area of the floor for a foot switch, and the holder can take any size of gouging rod, rough surface or not., I can angle the rod to the handle and it cost about a fiver (something like this http://ts1.mm.bing.net/th?&id=HN.608000295266617399&w=300&h=300&c=0&pid=1.9&rs=0&p=0 ) The other connection goes to a stainless steel base plate with a lip at the back (handy to stop round stuff rolling around). The big advantage with rsu compared to a conventional iron, is that parts don't move when you apply the heat source, and it heats up/cools down quickly, no messing about tinning the bit, and in my version, the power input can be easily and speedily regulated - (from about zero up  more than 1kW   )  I also use it for straightening wire.

[EKR]

My moment of liberation came when I ceased to use to use the metal plate and used the crocodile clip instead.

Simpler, faster and more flexible.

Transformed the tool for me.

 

The clip will get warm but I've never marked the brass with it.

[Jol Wilkinson]

A crocodile clip has several sharp contact points and does't give as much contact area as other methods and is therefore a point of higher resistance where you don't want it, something best avoided.

 

Much better would be some sort of small clamp with parallel jaws that gives a bigger contact area You could also solder or bolt the return lead (with an eyelet on the end of it) to the model. That works better in 7mm where the model has some weight and is more likely to stay where you want when working on it.