Thanks for posting this Ian. I have a London Road Models RSU which has sat in its box since I bought it last year at ExpoEM North, I think its time it came out and got set up. Have you tried pre-tinning with a conventional iron?

Paul.

I'm glad it's not just me that has problems remembering to move my foot off the switch before removing the probe. On the higher power settings there is an impressive flash if you forget!

I am quite impressed with the RSU I tried, although I think I'll use it mainly for building up layers and sweating components together - I much prefer a conventional iron for seam joints.

Please keep the posts coming - this is very interesting and useful.

Andy

My comments:

Yes from the photo it looks like the same RSU but mine has no black terminals. I generally always put the base terminal (crocodile) in the highest coded terminal - do not know why.

My main comment is that I think you are doing it all wrong. Sorry.

You have one massive heat sink and electrical continuity issue.

The RSU works by generating heat at the point of highest resistance. This should be at the point where the two pieces of metal to be joined are in contact only through the liquid flux/paste. In all your examples you have electrical metal to metal continuity through the "solder station" the result is that you are using a far too high a setting, generating too much heat and destroying you carbon tips. An indication of this is they are glowing red.

Try again. This time insulate one of the pieces to be joined from the "solder station" using a thin piece of card. Do it so that the only way electricity will flow is through the insulated part, through the join and to the other uninsulated part. Also realise that that massive heat sink is causing as much trouble as it would with conventional soldering, so also insulate it with card. Use the magnet or a small uninsulated area to provide electrical continuity.

Also I have found that when using paste the points to be joined have to be exceptionally clean and despite the use of solder cream the join still benefits from adding liquid flux. It is amazing how little cream is required to make a join - if you can see it - it is probably too much.

One final note: do not use the RSU for jobs that are better handled with a conventional soldering iron - typically seaming (if you do then use the RSU on the outside of the seam not the inside - but beware of arcing when you remove the carbon tip without turning off the power.

The RSU is a great tool to have but it doesn't replace the conventional iron. It is best used for those tiny joins of small components to large components. These are best handled off the "solder station" by attaching the black lead to the main component and the anode to the small part being added. It is then that you appreciate the power being used and the heat generated by the low settings. As on too high a setting the small part can be vapourised.

I used a home made RSU quite a lot when I used to build 7 mm locos. Get yourself some solder paint, expensive, but you don't need to use much of it. Have you got a foot switch with your unit, these can be very useful, when attaching thing like lamp brackets. The part can be held in position with the electrode and the “spare hand” while you control the power with you foot.

Gary

Is this a swanage models unit. If so I'm waiting for min to be delivered.

Is this a swanage models unit. If so I'm waiting for min to be delivered.

In earlier text it was described as "one of Dick Ganderton's 'Graskop' units" This is what mine also is and mine was one of the last one's sold by him. The London Road Models and Swanage units are essentially the same as this one (as are they all) and although the settings might be labeled differently their use remains the same. It is an expensive bit of kit to spend your cash on £100+ and they are heavy to post. But if you are an avid (near daily) kit builder you are likely to find it an invaluable tool. I wish I had bought one much earlier.

Solder cream beats solder paint on convenience every time as the amount used is so small. Solder paint still has its uses for tinning parts but requires care when used for overlays. The trapped flux can boil off very rapidly and blow off the overlay if not held firmly together.

There is a real risk when using an RSU for overlays, that is localised heating. The part is expanded by the heat and with thin overlays this can lead to buckling and distortion.

Hi folks - and apologies for the lateness of the hour!.

To answer some points -

David - yes this is the unit sold by 'Trainman' at Swanage. I wrote the initial article whilst at work, and could not for the life of me remember the details except it came from Swanage!

Kenton - many thanks for your comments & instruction. It seems I missed something (or forgot more like) at the ExpoEM demo - although I would have thought I would remember seeing card as an insulator.

I did wonder why settings like C(red)/D(black) did not appear to generate any heat. I'll try your method - although I might use the thin asbestos paper from the initial set of images, rather than card. More trials tommorrow then!

However, I have to say that the unit has performed well on the 4-4-0 kit today - although I do take DonW's point about not getting fixated with the RSU ('New toy' and all that) the RS temo controlled iron has been in use today!

On the matter of solders - I tend to use 'Neals' solder paint/paste for some jobs and 'RS' multicore for others - 'horses for courses' so to speak. Both have the advantage of being lead-based (and therefore very nonPC!) but it's only me that's at risk!

Right - back to the MSWJR page!

Regs

Ian