Henley Solon 25W Soldering Iron Revival

[ajgriff]

It’s always useful to have a back up soldering iron. For a long time an eighties Antex 25W XS fulfilled this role for me but unfortunately the plastic moulding around the element base recently crumbled away. My initial thoughts were to look at repairing or replacing the Antex but then I remembered that, in a fit of nostalgia, I’d acquired a Solon iron a few months before at a flea market for a couple of pounds. It came with a typically short, seized and corroded tip plus its original box. Like many other forum contributors a Henley Solon 25W Instrument Soldering Iron was my first electric iron. I still have that iron somewhere but haven’t yet been able to locate its exact whereabouts.

It’s difficult to track down new old stock tips these days so making one appeared to be a sensible option. Round copper bar is relatively expensive in very short lengths so I decided to buy a longer piece as it seemed worthwhile to make some extra ones for the lost iron and to retain as spares. A bit of research and careful measurement established what I believe to be the correct imperial dimensions as listed below, although the length is a bit of an estimate:

Diameter - 3/16”
Overall Length - 1 5/8” (approx)
Distance of split pin hole centre from base - 3/8”
Hole diameter - 3/64”
Face angle - 45 deg

Cutting and shaping the round bar was straightforward enough using basic workshop tools. However, drilling copper bar with such a fine drill proved to be rather more challenging than expected. Initial attempts resulted in a couple of broken twist drills and corresponding pieces of scrap copper with fragments of high speed steel embedded in them. It’s pretty much essential to use a drill press (fitted with a vice) or a lathe for such fine drilling but that isn’t the end of the story. After my initial troubles with broken drills I discovered that drilling pure copper of any great thickness requires correct lubrication and a technique known as pecking. I’ve never had any real difficulty drilling brass, steel or aluminium but apparently the trouble with copper is its softness and malleability. These properties cause drill bits to bind badly without clearing the swarf. Jamming leading to breakage is the almost inevitable consequence. I used sunflower cooking oil as the lubricant and that seemed to work well. Professional drilling jigs can be set to peck automatically but the required up and down motion can be replicated manually by drilling to a depth of about 1mm at a time, withdrawing the bit on each occasion.

Of course the other challenge with the Solon is extracting the old tip. Before attempting this it’s helpful to have a look at AEI’s instruction leaflet (PDF copy attached) which includes the recommended bit renewal procedure as well as a detailed drawing of the iron’s component parts. I managed to remove the tip by clamping it in a vice, switching the iron on and twisting the aluminium holder with pliers whilst pulling firmly using the iron’s handle without twisting it, in order to avoid straining the holder to element case screw fixing. A little releasing oil was applied the previous day. By the way, the split pin came out relatively easily, with only a little persuasion, once the iron was hot.

The photos illustrate some of the points mentioned above. I bought a pack of split pins which looked the right size but turned out to be a bit longer and very slightly narrower than the original. Once clipped to length they do the job perfectly well however. The fact that the iron came in a box branded AEI and priced in shillings means that it was made somewhere between 1959 and 1971 I guess. I’ve now used the iron a couple of times and it works just as well as I remember and will be fine as a replacement for the Antex in a back up role. It has a much more flexible cable too.

I hope that this post helps to pull together some of the information contained in a few older threads and that someone might be inspired to revive their old Henley Solon 25W Instrument Soldering Iron, for reasons of nostalgia if nothing else. If there’s any interest I could make a few tips available in the forum’s offered section and would only look to cover costs.

Alan

[MotorBikeLes]

My first PROPER iron was one of those, probably bought in 1954. I still have a few spares, maybe complete body (all new). However, I stopped using it after I saw sparks flying between bit and working load. Not much of a problem back the, or for the next 20 years, but with today's static sensitive stuff, BEWARE!
Les.

[high_vacuum_house]

Good evening,

If you want to produce more iron tips then this might be useful.

I have used a very good company in the past called “Noggin end metals” for bits of round copper bar. They have many different sizes of copper bar and you can buy larger diameters by the inch if you don’t want too much left over waste.

They do copper shim, copper tubing and many other non ferrous alloy stock metals.

They go to some model makers exhibitions and some steam fairs. They have an online shop and I have been most impressed with their service.

No relationship with the company but found them a really useful company.

Christopher Capener

[ajgriff]

Originally Posted by MotorBikeLes

My first PROPER iron was one of those, probably bought in 1954. I still have a few spares, maybe complete body (all new). However, I stopped using it after I saw sparks flying between bit and working load. Not much of a problem back the, or for the next 20 years, but with today's static sensitive stuff, BEWARE!
Les.

The Solon's tip is actually earthed in much the same way as the Antex XS or the Weller TCP for that matter. Problems arise in the long term because of a build up of non-conductive corrosion in an iron that has never been dismantled and cleaned. In the case of the Solon the attached photo helps to illustrate the point. It seems to be corrosion between dissimilar metals that leads to earthing failure. In particular this happens where the aluminium bit holder meets the inner surface of the steel tube in which the holder sits. Good old fashioned rust around the fixing screw for the holder doesn’t help either, nor does corrosion between the holder and the copper tip itself. With the revived iron I know that all the corrosion has been cleaned up plus there’s now no discernible resistance between the tip and the plug’s earth pin. For good measure I’ve also verified that there are no signs of insulation breakdown between the element and mains earth.

It might be worth adding a note of caution here for anyone planning to disassemble one of these. Even when adhering to the procedure set out in the instruction leaflet it’s very easy to accidentally pull the element’s coil plus associated mica out of its outer metal casing (sleeve). It’s really important to proceed slowly and to shake the assembly periodically so that the ceramic beads protecting/insulating the wiring don’t catch on the bottom of the tube. Also do not try to withdraw the sleeve from the base of the holder. It needs to be pushed out sideways from the slot with the coil and mica still inside. If the element assembly itself does come apart a good deal of consternation is likely to follow which could ultimately result in the iron being consigned to the parts bin.

Out of interest I checked the tip to earth resistance of the broken Antex as it does still heat despite the crumbling plastic. Surprisingly it’s about 4.5k presumably because of corrosion involving the inevitably seized tip.

Alan

[duncanlowe]

The first iron I used as a child was one of these too borrowed from my Dad. I got a weller temperature controlled (240v) iron of my own for my 18th. I still have the Weller, and recently got the Solon back as my Dad has moved and no longer has anywhere to keep or use anything but basic tools.

[Phil G4SPZ]

Great idea Alan and some useful information from other contributors too. I grew up using a 25 watt Solon and I now have two, one standard 240 volt example and one, very little used, 110 volt model. Neither needs attention just yet...

[ColinTheAmpMan1]

I can see the usefulness in this, as I too have a Henley Solon 25W iron, which I use on old valve circuitry. A fellow member of this forum provided me with a NOS bit, for which I am and was, grateful, but if they are unobtainium now, then I suppose this is the route to go. It may be worthwhile, though, to point out that I believe the original bits were iron-plated and shouldn't be filed, thus removing the iron-plating. The plating was there to reduce bit wear. It would be interesting to know if iron-plating might be possible some way.

I also recall that there was an idea that, apart from removing the bit periodically for removing corrosion and preventing the bit from seizing in the alloy holder, the bit could be wrapped in some thickish aluminium foil (such as small cakes come in) placed between the bit and the aluminium holder. This apparently reduced the rate of formation of heat insulating oxides and prevented seizure of the bit in the holder. I have done this on my iron and the bit "wiggles" a little, so perhaps I should try removing it and removing oxide build-up.
Colin.

[ajgriff]

The bits weren't plated and have to be filed occasionally to remove oxidation which is why they eventually wear down. I've not tried the foil trick but regular wiggling and occasional removal does keep the bit from seizing in the holder. It's important not to keep removing material from the inner surface of the soft aluminium (alloy?) holder otherwise the bit becomes an ever looser fit. In some one ways the holder is the most vulnerable part of the iron and would be very difficult to replace.

Alan

[Refugee]

Has anyone tried iron plating copper bits?

[ColinTheAmpMan1]

I have found a PDF file of an instruction sheet that was posted on this thread in post #1 . The bit is described as being chromium copper and the retaining split-pin is stainless steel. I have no idea where I got the notion that it was iron-plated, but at least it wasn't originally pure copper. Maybe it was a different iron entirely (Antex, possibly). I remember that the tip of the bit used to develop a "crater" with prolonged use, which was why it was sensible to file it flat.
Colin.

[ajgriff]

Yes, they were originally chromium copper which is somewhat harder and a bit less susceptible to erosion/oxidation than pure copper. Trouble is I've not yet managed to find a supplier of 3/16" chromium copper round bar with a minimum order quantity of less than 10kg so pure copper will have to do for now! The split pins I bought are stainless steel like the originals.

Solon tips definitely develop a crater after a while. Apparently copper has a tendency to dissolve in molten tin but I'm no metallurgist.

Alan

[barrymagrec]

When I was an apprentice I was issued with a 25W Solon with some sort of plated bit, I found it useless for soldering until I filed the tip and I have never wanted to use one since.

In the old days of unplated copper bits you could buy Savbit solder which contained a small percentage of copper which was supposed greatly prolong the life of the bit. Should you have the misfortune to need to use lead free solder with an unplated bit you will find you get a significant hollow after less than a dozen joints

[The Philpott]

I have one of the Solons you have pictured here Alan, i would certainly go in for replacement tips if you wanted to run off a few.

Dave

[duncanlowe]

Copper bits being 'eaten' away by the solder is a recognised issue, which is why Savbit solder came to exist. It was said to prolong the life of the bit by reducing this erosion. With modern bits I haven't seen any since my childhood.

[ajgriff]

Originally Posted by barrymagrec

When I was an apprentice I was issued with a 25W Solon with some sort of plated bit, I found it useless for soldering until I filed the tip and I have never wanted to use one since.

I wonder if it really was plated? The attached photo is of the replica tip on show in the original post but after being used on just a few occasions. Notice the spots of black cupric oxide. It won't be long before the entire length is evenly blackened giving the appearance of plating. This would also explain why your iron worked better once the tip was filed. Just a thought, but in any event I'm more or less certain that Henley Solon never made plated tips even after GEC got hold of the company in 1967.

The funny thing is that I never had a problem with cleaning up the tips but that's probably because I learnt to solder with one of these and tip maintenance was just a routine aspect of soldering as far as I was concerned. Even today I've been known to file tips with damaged plating so that I can carry on using them for a while.

As far as Savbit is concerned I notice that it's still claimed to prolong the life of plated tips although I'm not too clear how that works. One way or another I've never been convinced that Savbit makes much difference to tip life whether the tips are plated or not.

Alan

[TowerRadio]

Bits were definitely coated with something like hot-dip galvanising. Pic from eBay.Les

[ajgriff]

The leaflet implies that the coating (not plating) is there to protect the tip from corrosion before use and advises that it should be removed before tinning. Aside from that it doesn't look like a Solon 25W tip. The base is rounded, there's no hole for the split pin and the chisel shape doesn't correspond to the Solon design.

Alan

[emeritus]

I bought a reel of "Savbit " Tin-Lead-Copper solder from RS a couple of years ago.

One of those Henly Solons was my second electric soldering iron. My first was an unbranded one that I got as a Bingo prize in Southend when I was a schoolboy starting to get interested in electronics. It burnt out after a couple of months so dad took me out and bought a proper one which I still have somewhere in the garage. Before that, dad used to use a small traditonal soldering iron that had to be heated up on a gas ring for his occasional soldering on valve radios.

[Phil G4SPZ]

Alan, this thread has inspired me to look closely at my Solon irons. The 110 volt one will be needing a new bit in the near future. I’d have preferred to make my own, but as has been reported, copper bar of the right size isn’t readily available. I considered getting some 5mm diameter and turning it down in my watchmaker’s lathe, but at £9 for a short length (most of which I’ll probably never use) the sensible thing would be to ask you whether you are prepared to make some available. You have at least two customers already!

[Phil G4SPZ]

Originally Posted by Phil G4SPZ

I’d have preferred to make my own... I considered getting some 5mm diameter and turning it down in my watchmaker’s lathe, but at £9 for a short length...

Update: I found some 5mm diameter copper bar in 100mm lengths much more cheaply, so I decided to go for it. If anyone else is equipped to do this, the dimensions (in metric, sorry) are attached. After turning down to size and parting off, I fitted a 1mm drill in a collet in the lathe headstock, and clamped the bit to the tool rest. 3-in1 oil seemed to work fine as a lubricant. Alan is quite right though; drilling copper needs a ‘little and often’ approach.

One advantage of the ‘shoulder’ is that the new bit doesn’t wobble at all when installed. It would be a simple matter to turn the tip down to a smaller diameter if desired.

The old split pin broke as I was removing it, but a short piece of copper wire served as a replacement.

Phil