How to Repair a Broken Z-Clip

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Fountain pen
Fountain pen

Introduction

The Z-clip is so called because, if you remove it from the pen and look at it from the side, you can see that its zigzag shape resembles that of the letter Z. Here is the cap for a pen made by the National Pen Products Company, and below it is the clip alone.

Cap
Clip

Back in the early 20th century, the number of pens with Z-clips was probably astronomical. Today, the number of pens with broken Z-clips, while not astronomical, is still alarming. Most Z-clips break when corrosion sets in at the bend where the clip enters the cap. (The clip in the illustration above shows the beginnings of corrosion at that location.) With a pen whose clip is not imprinted with a design or a brand name, this failure is relatively unimportant because replacement Z-clips are readily available. On the other hand, a clip that is imprinted with the pen’s brand name or an attractive design can be virtually irreplaceable, as was the case with the clip on the lower pen illustrated at the top of this page, a Master Pen made by the Bankers Pen Company. This article shows one way to repair such irreplaceable clips.

Tools Required

Supplies Required

Disassembly

As illustrated above, the Z-clip has a tab, inside the cap, that projects toward the cap crown. Below is a sketch of a Z-clip, with its parts labeled. To install the clip, the tab is inserted through a slot in the cap and clamped to the inside wall of the cap by the inner cap.The angled bends in most Z-clips are bent more than 90° so that the angles are acute, as shown in the photo above. The looser bends in the clip in this sketch more closely resemble the bends in the clip on the Bankers Pen Company’s Master Pen.

Z-clip

To remove the clip’s broken tab and create the space needed for the new tab, you must first remove the inner cap.

Removing the inner cap
CAUTION
CAUTION
Do not use an inner cap remover that does not have a thrust bearing (consisting of a circular race of needle bearings and two washers)! A remover without a thrust bearing can easily damage the cap lip as the lip slips against the end of the remover’s body instead of rotating smoothly on the bearing.

With the inner cap out, you can remove the broken tab. Sometimes it will fall out, but it is often stuck to the inner wall of the cap by dried ink or corrosion. If it is stuck, use the dental pick to pry it loose. Set the tab aside; you will use it later for a measurement. Then clean the inside of the cap with water and a test tube brush. (Clean the inner cap, too, while you have it out.)

Repairing the Clip

The next sketch shows the broken clip together with a replacement tab for it.

Z-clip

Using your rotary tool, you can make the replacement tab by cutting off the clip body from a sacrificial clip of the same material as the original (nickel silver or gold-plated brass); or you can fashion a completely new tab from strip brass, using your flat-nose pliers to form the bend. The replacement tab should be shaped so that the clip overlies it as shown by the red arrow in the sketch above. Cut the shorter arm of the tab to length so that the two shorter arms just overlap, with each one’s end butting up against the longer arm of the other part. Then trim the tab so that its width is the same as the width of the broken tab. If you have no broken tab, trim the tab so that it is very slightly narrower than the clip.

Clean the mating surfaces of the tab and clip very carefully. An 80-grit (yellow) radial bristle brush is the best tool for cleaning the parts to ensure that you have a clean bare metal surface on each one. If you do not have this brush, you can file the surfaces clean or, as a last resort, sand them with 320-grit sandpaper.

Clamp the two parts in the third hand, bringing them together so that they are in exactly the positions you want them in when you have finished soldering, as shown here:

Z-clip
Soldering the clip
WARNING
WARNING
Use care when soldering; the iron itself is extremely hot, and the liquid solder is more than hot enough to give you a nasty burn.

Sweat-solder the parts together by applying heat to one edge of the joint and allowing the iron to heat the clip and tab until the solder, applied to the opposite edge of the joint, melts and flows between the parts by capillary action. The red line in the sketch above shows where the solder should be. Remove the soldering iron and allow the joint to cool enough to set completely before removing the clip from the third hand.

Using needle files and the X-acto knife, clean away any excess solder from the edges of the joint and from the front face of the tab and the back face of the clip. The goal is to produce a repair that looks as if it never happened, except that the place where the short arms of the two parts are overlapped is twice as thick as the rest of the clip. If the soldering process got the clip hot enough to oxidize the plating, you can remove the oxidized surface with a Sunshine Cloth or other chemically treated non-abrasive jeweler’s cloth.

Now, using a cutting wheel in the rotary tool, carefully grind away the portions of the replacement tab that are visible at the overlap. Lay the clip against the flat surface of the wheel as shown here; do not try to “sculpture” the material removal using the edge of the wheel.

Trimming the clip

Do not cut into the material of the original clip; the object is to create the original appearance of a single thickness of metal. Done correctly, this operation creates sloped surfaces on the underside of the clip, leaving at the exposed edge only the single thickness of material that should be visible. The sketch below shows how the sloped surfaces should look.

Cut-away areas on underside of clip.
Note
Note
This step emphasizes the need for a good solder joint. If the joint is insufficiently heated to cause a good flow-through of solder, there can be air pockets in the joint, and a joint with air pockets will be very weak.

Making It Fit

The extra thickness of the clip where it will enter the cap means that the clip will no longer go into the cap as far as it needs to. The solution to this problem, however, is very easy. Use the X-acto knife to shave away a little material from the bottom edge of the slot in the cap wall, as shown by the red line in the sketch below:

Cap modification

Take off only the minimum amount of material necessary to allow the clip to fit into the cap. If you remove more than needed, the clip will fit sloppily in the opening and will able to wiggle. This can enlarge the hole, further exacerbating the problem. The end result can be a cosmetic nightmare as well as structurally unsound. To ensure that you do not remove more material than needed, cut away only a very thin shaving of material and try the clip in the slot. If it won’t go through, take a little more, “walking” the opening wider step by step until the clip just fits.

Finishing Up

With the clip and cap modified, all that remains is to reassemble things. Slip the clip into position and then insert the inner cap. Some inner caps are flattened or notched on one side to allow the clip’s tab to fit, and if yours is one of these, you will need to be careful to align the relieved area of the inner cap with the clip before pressing the inner cap home. With everything lined up, push the inner cap into the cap until it stops. Shown here is the finished repair on the Master Pen that inspired the writing of this article.

Finished repair

The information in this article is as accurate as possible, but you should not take it as absolutely authoritative or complete. If you have additions or corrections to this page, please consider sharing them with us to improve the accuracy of our information.

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