We recently had a batch of vintage Yard-o-led propelling pencils sent to us for repair and restoration. One in particular was such an excellent example of what makes these pencils so outstanding that we thought we would share it with all of you.
Since Samson Mordan patented the first helically-driven propelling pencil in 1832, not much has been done to improve on his original design. Yard-o-Led, established in 1934, used Mordan‘s basic design, but made several improvements (which we will point out as we go along.) In the earliest days of the company, their manufacturing was outsourced to Johnson Matthey & Co, thus the “JM&Co” hallmark on pencils like this one.
Yard-o-led products come with a famous lifetime warranty, and this information is not meant to replace the care of a qualified technician. If you have a Yard-o-led pencil, we encourage you to contact them and arrange for service that way.
However, there may be occasions when you want to do some work on your pencil yourself, or when you feel that it would not be appropriate to assume their warranty would apply (such as destructive damage due to abuse, or coming into several parts pencils which could be combined into a working one.) In the interests of education, and to help foster an appreciation for the fine workmanship produced by this company for decades, we are happy to provide this information.
I. An Overview
So here we have a typical Yard-o-led pencil of the era, in sterling silver, hallmarked for 1946. It is round in cross-section (other models were triangular, square, and hexagonal), and 117 mm (4 5/8″) long. This particular model has a brass nozzle (where the lead comes out), and a clip which is riveted to the body (earlier models had a loose clip, held in place by the retaining nut, which we will talk about below.) (note: the clip in the photo is sprung a bit; we tightened it up later on. There should be no space between the clip and the pencil’s body.)
II. Simple Dis-assembly
These pencils are meant to come apart to a certain extent, which is one great advantage to Yard-o-led products. It means that any owner can carry out basic maintenance, including cleaning and drying (more on the importance of drying things out later.)
The first step in simple dis-assembly is to unscrew the nozzle (although not all models had a removeable nozzle.) It should be on tight enough that you have to use a piece of rubber to grip it hard enough to unscrew it. Sometimes a bit of heat can be used to break any corrosion bondspass the end through a heat gun until it is warm to the touch. If neither of these methods work, don’t force it. It may have been cross-threaded in place by someone careless, and in that case not much can be done but to leave it be.
On the other end, retract the lead as far as you can. Then, pull up the plunger/drive shaft assembly as far as it will go. Loosen the retaining nut off completely, and then twist the drive shaft out of the pencil body. (In the photo below, the brass baffles for the storage silos have also started to pull out. That almost never happensI loosened them before I took the photos.)
You should end up with: the pencil body; the unthreaded nozzle; the drive tube/plunger assembly; the retaining nut, probably still on the shaft.
III. Not-So-Simple Dis-assembly
Now for the more difficult part. Because there are brass parts inside the pencil, and because brass tends to corrode into a greater volume than when it began (unlike silver, which just changes colour), things tend to get stuck together. We take a couple of simple steps to clean and loosen things up. First, we soak the barrel in warm vinegar (known as a pickle solution in the metalsmithing trade), which dissolves any corrosion. Second, we run it through an ultrasonic cleaner, which vibrates off any dirt or muck quite effectively. One reason this pencil is before you now, is that it was looked after: kept dry and clean. There was very little dirt or corrosion cementing the pieces together, and the inner workings literally just lifted out:
The threaded propulsion tube is enclosed by the storage baffles, which are thin brass, press-fit together into one piece. The easiest and safest way to try and get this out is to replace the retaining nut, and use it as a handle to gently pull on the assembly, trying to gently work it loose. Again, soaking and/or gentle heat can help. However, the barrel and threaded tube are so thin that they can be easily damaged. Sometimes this part just cannot be safely removed. Often the storage baffles will come out, but again be careful, as they are easily deformed.
The storage baffles are loosely held around the inner drive tube. If you can get them out, then they can be pickled in warm vinegar and rubbed with the finest of steel wool to clean them. A small test-tube brush can be used to clean the interior. This cleaning and polishing goes a long way to rehabilitating the lead storage silos, and is often all that is needed to keep access to the full “yard” of storage capacity.
If we take a look at the cone, we can see where some of the only soldering is on these pencils: where the cone fits over the drive tube. This is why we are careful about using heat to loosen the inner assembly or the nozzle. Lead solder melts at around 176ºC (349ºF), and it is very difficult to re-solder brass and silver accurately again! This is also why we can’t just drop one of these pencils into a silver pickling solution: the tin in the solder will muck up the pickle, and the steel spring (which we will show you later) will actually copper-plate your pencil! So, vinegar, the ultrasonic cleaner, and steel wool are again the best cleaning agents.
You will notice the slot milled along one section of the cone. This is so that it can get past the clip rivet. One sign of quality in the Yard-o-ledpencils is that, rather than just using two wee rivets to hold the clip in place on the body, they used a more robust system. Inside the barrel is actually a small bar of silver, parallel to the tube, with the two rivets projecting out of it, through the body, and through the clip. These two rivets are then hammered out to hold the clip in place. Thus, the clip is held in place by one large, long, solid piece of metal, which is why it rarely works loose. Our hats should go off to Yard-o-led for choosing good engineering over cheap expedience!
IV. Shuttling About
To round out our understanding of these pencils, we need to examine the shuttle: the bit which actually holds the lead and moves it up and down the drive tube. And a picture is worth a thousand words:
The three bumps which protrude from the slot in the shaft engage in the threads of the drive tube. When you twist the finial, the shuttle moves up and down, following the threads. This is Samson Mordan’s genius at work, and simple machinery at it’s best! For the purposes of demonstration, we have placed two parts removed from other pencils next to the mechanism from this one.
A closer look shows us that the shuttle itself is made up of three pieces: the outer shuttle, the inner shaft, and a steel spring (the only steel in these pencils.) The shuttle body holds the lead in place (sometimes this gets bent or loosened. It can be re-shaped to hold leads more firmly if necessary.) The brass inner shaft both engages the drive threads and serves to expel the lead from the socket when the mechanism is fully extended. The spring serves to ensure that the lead is only expelled at that point of full extension. AS you can see, the inner shaft is held in place by two tiny folds of silver at the mid-point of the shuttle body.
The steel spring is one reason why it is so important to limit water exposure. Because of it’s small size, it will rust very quickly. And because the barrel is completely enclosed, evaporation is very limited. So, washing a pencil is guaranteed to shorten the lifespan of the entire ejection mechanism. (If a pencil does get flooded, compressed air is the best way to dry it out. WD-40 is a water dispersal agent, but it is greasy and stinky, can collect dust and muck over time, and should not be used. Only use a good graphite lubricant for mechanical pencils, and only use a dry graphite lube for any vintage pencil with plastic parts.
V. Body Work
With the pencil apart like this, it is a great opportunity to look at the body. A good set of mandrels is indispensable is servicing pencils; a set of machinists’ “transfer punches” is perfect. In this case, as soon as I slid the mandrel into the end of the barrel it was plain to see that it was slightly out-of-round, which effectively prevented one third of the barrel from being used for lead storage. A little quick re-shaping with a wee teflon-faced hammer fixed that problem. A mandrel just smaller than the diameter of the clip rivet worked well to support the minimization of some dents.
Any time we do work on sterling silver (a portion of which is copper), and gold alloys for that matter, we have to keep a few metallurgical principles in mind. Any copper alloy will harden the more it is worked; the crystal lattice of the metal is literally compacting more and more, to the ultimate point where it will fracture. This means that any dents are harder than the surrounding metal. So, if you simply push on a dent, the tendency will be for the surrounding metal to rise up, so that you end up with an in-dentation within an out-dentation. The entire area to be worked must be fully supported, and the best method is to roll out the dent, rather than hammering. (As a quick aside, one reason you often see dents just above the cone of these pencils is that they are so well supported inside by the cone at the tip of the drive tube. At the point at which the support is gone, the dent-causing force collapses the thin tubing making up the body.)
One means of avoiding metal stress in copper alloys, and of equalizing the hardness of the worked and non-worked areas is to anneal it, heating it to red hot with a blow torch. This process can only soften the metal, and will never harden it. However, because copper transmits heat so efficiently, the entire area of this thin metal tube will quickly become very soft. This may make for easy dent removal, but also makes for huge vulnerability to future denting. When we say soft, think of the consistency of refrigerated butter! This can also make any decorative pattern cut into the body more prone to wear.
So, when it comes to dent removal, balancing aesthetics with wear-resistance is vital. Sometimes you just have to put up with scars.
VI. The Complete Picture
So here are all of the parts of this 1946 Yard-o-led pencil, broken down. We could conceivably de-solder the cone from the threaded drive tube, but that shouldn’t be necessary too often. To reassemble the pencil, we can simply follow the steps backwards.
Yard-o-led made, and still makes, an excellent, world-class pencil. They are simple enough to be robust, and complex enough to do the job well. With a little care and thought, many forgotten or abused pencils can be brought back to life for more decades of service.
Our thanks to Irvine, for his kind permission to use his pencil in this post.