Parker “51”: Who’s On First?

Tony Hawkins asks: Please do tell me — exactly how do I tell the 3 “Marks” apart? I have read Lambrou together with various other book references and e-mail sites but they all seem to vary (except possibly for the various versions of the Mk 1). I should be extremely grateful for any assistance you can give.

The question of which “51” is which is likely to be debated into the next millennium. However, the parker service manual does give clear indication as to which model Parker thought was which. (I qualify this because there some overlaps; as with many products, changes can phase in over time rather than all happening at once.) First off, any aerometric “51” with a date code is a Mark I. For the millions of undated pens out there, here’s what Parker and I have come up with:

• The most common aerometric “51” is the Mark I. Externally, this pen is identical to the Vacumatic-filling version except that the barrel no longer ends in a blind cap and that the Split Arrow clip is gone, replaced by the plainer Arrow clip:
  
  
  The filler in a Mark I pen has a plastic end cap:
  
  
  
  A subtlety to watch for, however, is the filler of the “51” Demi. Early aerometric Demis have fillers like that of the standard model; but later Demis, beginning probably in 1949, use the less costly “hoop” filler design introduced in 1948 on the “21”:
  
  
  
  At some point, probably in the late 1950s, Parker introduced a slight variation on the Mark I design. In this apparently undocumented “Mark Ia” version, the aerometric vent hole is moved from the end of the barrel to the side of the barrel, about ²/3 of the way from the clutch ring to the end.
• In the mid-1960s, Parker began producing the Mark II “51”. This version, redesigned to update its look, bears a noticeable resemblance to the 61. Its cap has a 61-style clutch, with fingers bearing on the hood instead of on the clutch ring, but the standard “51” clip is still present. The end of the barrel is squared off to a shallow conical shape that mimics the cone of the cap jewel:
  
  
  Internally there are significant differences, as Parker redesigned the internal parts to simplify the sac guard and replace the costly machined collector and feed with molded plastic parts. The most noticeable internal change is in the sac guard, now a single piece of metal with its end formed closed instead of being capped by plastic:
  
  
• The Mark III “51” appeared in about 1969. This pen looks similar to the Mark II. The cap shows the most visible external change. The clip, a new 61-style long Arrow clip, is no longer part of the cap’s decorative trim ring; it is a separate part. The trim ring and jewel are combined into a decorative clip screw that holds the clip in place as on the Parker 75. The clutch ring, which is not functional, is now reduced to a narrow trim ring.
  
  
  The Mark III’s sac guard looks like that on the Mark II, but the trim ring identifies the later pen. You can also see on closer examination that the threads on the Mark III’s connector are rather coarser than those on earlier pens and that they have an Acme profile (flat on the crown and at the root).
  
  

Front-End Disassembly and Reassembly of the “51”

Earl Forman asks: How do you seal the section to a 1942 Parker “51” (full size pen) to the metal ring after it has been removed to service the collector, etc.?

Jonathan Sims asks: I have just acquired a new nib for my Parker “51”, but am not sure how to take it apart so it can be fitted. Advice would be welcome.

The hood on a “51” is held in place with an adhesive that softens when heated. I recommend using a commercial heat gun with a continuously adjustable temperature control. (Guns with Low and High settings are, for pen-repair purposes, mislabeled; the labels should read Way Too Hot and Even Hotter.) The adhesive softens at a much lower temperature than would be needed to damage the hood, so you should keep the gun set very low. Too much heat, too fast, will shrink the hood — especially on Mark III pens, whose plastic is polystyrene rather than the earlier Lucite^®.

1. Remove the pen’s barrel. If the pen has been allowed to dry with ink in it, soak and flush it thoroughly before attempting to disassemble it; dried ink does not release under heat, and too much force can break the pen. Heat the area of the hood adjacent to the clutch ring for a minute or so, spinning the pen slowly so that all sides will be heated. Then grasp the clutch ring and the threaded barrel connector firmly (I use section pliers) and unscrew the hood (I use a second set of section pliers). If it won’t come with relatively little effort, it may need more heat.

2. Some versions of the “51” have a rubber O-ring at the joint between the hood and the clutch ring. If yours is one of these, the hood will resist being unscrewed after it has come loose far enough that you know it should come off. If this happens, screw the hood back down, screw it off again until it binds, pushing just a little to force the O-ring to let go a little. Repeat this back-and-forth procedure until it finally frees the hood.

3. Once you have the hood off, you can simply slip the nib out of the end of the collector with a gentle pull, twisting slightly back and forth to rotate the nib and break it free if it’s a little stuck.

4. While you have the pen apart, go ahead and remove the collector, slip the feed out of the end of the collector, and clean the whole shebang before reassembly.

5. The first step of reassembly is to assemble the collector, feed, and nib. The collector has a thin slit running almost its entire length, and a broader air channel running along the opposite side of the finned area. Insert the assembled feed and breather tube, and then the nib, into the collector with the top surface of the feed and nib lined up as exactly as possible with the broad air channel. This is the way the original “51” design documents specified assembly. A later Parker service manual stated that aligning the nib and feed with the air channel isn't necessary, but my experience indicates that the pen will flow more reliably with these parts aligned.

6. Set the collector assembly aside. Screw the hood onto the connector until it stops against the clutch ring. Take careful note of how the point of the hood aligns with some mark on the sac guard; if it's right in line with the top edge of the word PARKER, for example, that’s your “index mark.” (Some repairers make a small mark on the connector next to the collector’s capillary slit before disassembly, but that does not work reliably because the parts won’t necessarily line up the same way on reassembly.) Remove the hood again, and insert the collector assembly. Align the collector assembly so that the nib is just barely not in line with your index mark, such that the hood will need to turn an exquisitely tiny fraction of an inch past where it stopped when you tested it.

7. Test the hood’s alignment again. The point of the hood should be about in the middle of the right tine. If it lines up with the outer edge of the tine, that’s too much; it’ll need to be forced too far when you screw it on permanently. If it lines up with the slit, that’s too little; it won't hold things securely enough to keep the clutch ring from spinning around the pen’s body.

8. Apply shellac to the threaded area of the connector where it will be covered by the hood. Screw the hood on, taking it all the way down, and use just enough force to align the hood with the nib. Clean off any shellac that squeezed out; I find that Simichrome, applied with the fingers and wiped off with a clean flannel cloth, works well for this.