Resistance Soldering Units

[S7BcSR]

RSU's may be one man's meat, but another man's poison.

I don't use an ordinary soldering iron for anything other than electrical work these days, I find the RSU works well for everything I want to do including soldering white metal to brass/nickel silver and for putting white metal kits together.
There again I could never get on with an ordinary soldering iron, despite my father spending hours teaching me as a kid and trying to follow all the rules. One day it would be OK, but the next it was a shambles again.

I bought an RSU in the 90s from someone down Portsmouth way and I have never regretted it. I must admit that it took a wee bit of, oh just get on and do it approach, to try my first white metal kit but it worked and yes I did make one slight mistake which needed sorting out but there again I had exactly the same happen with an ordinary soldering iron on my first white metal loco as a teenager. I have recently started attaching dropper wires to rail with the RSU and my, what a difference it has made to the neatness of the job.

These days I use a very similar approach to Raymond Walley with an iron plate with aluminium foil wrapped around it, aluminium angles to keep things upright and magnets to hold things in place. I think this came from watching Bernard Weller give a demonstration and me thinking this looked a sensible approach. Of course clipping one terminal to the aluminium angle gives me the circuit without having to try and find somewhere on the model to attach it which won't interfere with the soldering itself.

This is just my way of working and I have every respect, probably a bit of envy even, for those who use ordinary soldering irons.

Rob

 

[Dave]

To explain (I hope!)

View attachment 22183

Not a scooby... Are those lines representing extra cables that you need to plug between the different red sockets?

I seem able to cope with just the three anyway. The one farthest from the black for fine details and handrail wire, the second for plates such as cabsides and the third for anything else. Anything else that doesn't need a blowtorch anyway!

 

[daifly]

They show the pair of sockets into which you plug the two leads. If you are using the outer pair, you are using 4.5V. if you want the lowest setting (1V), then use the centre pair.

 

[daifly]

The "pumping of a lot of amps into a tiny spot" is another thing I have misgivings about. When I had an RSU it was supplied with a pencil tip, unfortunately this tended distort the brass due to the very localised heating. Yes you want plenty of heat into the joint quickly, but when it is very localised it can cause more problems with distortion. Also pump up the amps too much and you may get localised "de-zincification", brass being a copper-zinc alloy, localised high heat can leach out the zinc in the brass resulting in spot points where the brass weakens and appears porous.

Isn't that why there are 6 different voltage settings on this RSU? With your soldering station, you will use a variety of temperature settings to suit the solder in use and the items that you are soldering. Too high a temperature with the ERSA could surely also lead to some or all of the problems that you ascribe to the RSU.

 

[ZiderHead]

I'd never heard of resistive soldering until these recent threads. Intriguing idea and sounds rather like MIG welding, is it easy to solder along a seam using an RSU and feeding in solder from a reel as you go or is it more suited to a spot welding type technique?


NB Theres more than a little irony in a gentleman called Mr Weller promoting RSUs as an alternative to soldering irons

 

[Brian Wainwright]

My only comment is that I never completed an etched kit until I lashed out on a RSU. Now I've completed several, although I don't pretend they match the quality of professional work.

My main 'issue' with the RSU is that on odd occasions I've tried to solder fine brass parts on too high a setting, and the said parts have just vanished. This is good for those members of the trade supplying lost wax parts that I can substitute, but the moral is to use a lower setting when adding fine detail.

 

[lnerjp]

For my two pence worth, I bought one of these units a couple of years back, when I first got it I thought it was great, but after a couple of months I found myself using my normal iron all the time. I think in the end it came down to time, I can work much, much faster with my normal iron, and altough I normally ended up using more solder with a iron, it's very easy to spread the solder to a thin coat, that wipes off very easy with a fibre pen. So after about a year I sold it.

One thing I did find was that Raymond raves about Carr's solder cream, and with no amount of experimentation could I get decent results with it, I tried every setting on my RSU, but it would not flow properly and would just spit blobs of solder about, which looked like I had being trying to arc weld.

We are all different.

J.P.

 

[Eastsidepilot]

I'd never heard of resistive soldering until these recent threads. Intriguing idea and sounds rather like MIG welding, is it easy to solder along a seam using an RSU and feeding in solder from a reel as you go or is it more suited to a spot welding type technique?

An RSU is just another form of applying heat to the job in hand the same as a soldering iron does. With the RSU it takes some short time to work out the the best setting for the item/s that you are soldering.
Personaly I wouldn't be without it nor would I be without my soldering iron both have their main uses.
The RSU I find is ideal, quicker and cleaner for etched overlays, brass castings ( domes and chimnys etc) and boiler bands, window frames and coach body work especially bolection mouldings.
Loco frames, cabs, boilers etc. I find best done with the iron.
I have no problem with solder paints, the alternative is tinning the items first.

Col.