Questions About Sheaffer Vac-Fill Repair

[SilverPearlVacumatic]

 

I understand that the Sheaffer vac-fills have a reputation for being some of the most challenging vintage fountain pens to repair. I am planning on repairing a few for the first time and I have some general questions about this pen.

 

First, why is it recommended that the section and blind cap be removed to access the seals? Why not heat the back of the pen to remove the packing unit? If the packing unit was already loose (as in my case), should a different repair method be used?

 

Second, how many of these pens can still work reliably in unrepaired condition? Provided that the rubber washer is still in good condition, would a little silicon grease to the plunger rod be enough to bring many of these back to working condition, even if it takes a few strokes to fill it? Even if there was a leak, I don't think it would damage anything since the whole filling mechanism is designed to sit in ink (aside from the blind cap threads). How tight of a seal is necessary for the pen to work adequately?

 

Third, what's the purpose of the small washer on the plunger rod? Is that to better show the level of ink by separating it from the air or did it originally secure a seal?

 

Thanks

[Ray-Vigo]

The "normal" approach is to heat up the nib unit so that the nib unit unscrews from the section (the "section" being that black area just below the nib. What you should find is that the nib and feed are attached to a base that unscrews from that black area of the pen. You then remove the blind cap (and any retainer bushing), which allows you to push the plunger rod assembly out the front of the pen.

 

What has happened on your pen is something that happened to me a couple of times, but certainly not every time - your entire packing unit (that black cup-like assembly that goes into the barrel and holds the various gasket washers) has fallen out of the barrel. So you can actually do this repair from the back end of the pen, seeing as the unit just fell out whole. You will just need to be sure that you have re-secured the packing unit cup back into the pen when you are done with the restoration. I used 2-part clear epoxy to glue the unit into place when it happened to me. You'll want to be sure you set the packing unit cup to the proper depth in the barrel when you epoxy it back in.

 

I do not suggest trying to re-use the old gaskets - invest in the proper rubber parts from Dave Nishimura, Gerry Berg, Ron Zorn, etc (pick your vendor, just stick with someone who knows fountain pens). Now that you have the rubber parts out, you might as well replace them.

 

The purpose of the small rubber headgasket/washer on the rod is to generate the vacuum necessary to fill the pen through actuation of the plunger rod.

Edited August 28, 2019 by Ray-Vigo

[Ron Z]

The fact that the packing unit came out of your pen is an anomaly. Sheaffer did not intend them to come out, but sometimes they come loose, most often on these early war time Triumph pens. Sheaffer's instructions said to drill out the packing unit and replace it. We don't have that luxury.

 

Richard Binder and I spent a year playing with these things before we started to take them in for repair, and concluded that the safest way to restore the pen was to take the nib out and drill out the packing unit from the inside. The blind cap must come off to get the plunger rod with its head gasket out prior to drilling out, and rebuilding the packing seals. By the way, we rarely find these pens working at all, let alone working properly when we find them.

 

The back end of the pen must be absolutely air tight and water tight. If it is not air tight, the pen will not fill much if at all. Pushing the plunger down creates a vacuum in the barrel, which is released when the head gasket reaches the part of the barrel where the barrel widens. A bad seal means a bad or no vacuum, which means that the pen won't fill, and is likely to flood.

 

The packing unit was alternating layers of grease impregnated felt and rubber. Eighty years later, the grease has evaporated, and likely worn, and the rubber hardened. The Viton 0-rings we use are both chemical and wear resistant, and with a little silicone grease from time to time so that the plunger moves freely, should last a very long time. I have some that were restored 11 or 12 years ago, and are still going strong.

 

The head gaskets found in these pens were graphite impregnated rubber. They need to be flexible so that they maintain contact with the barrel wall, and can flex forward and back depending on the direction that the plunger rod is going. They're usually hard and rigid now, or missing all together having hardened and fallen apart. They must be replaced. The rubber should be a high grade buna-N rubber as close to 26 thousandths thick as you can get it. The stuff we use is 27 thousandths. Most rubber on the market is too soft, and either 15 thousandths (way too thin) or 31 thousandths thick. The little washer that you see is a backing washer, which is there to limit how much the head gasket flexes, providing the rigidity needed to create the vacuum as you push the plunger down.

 

I've tried solvent welding the packing unit back in the pen, and using shellac. Neither has proven to be adequate. Given that Sheaffer did not intend these to come out, I use a high grade (and expensive) epoxy to secure the packing unit in the barrel. Careful cleanup of the excess is recommended.

 

If you are going to the Ohio show in November, I will be doing one more seminar on restoring the Sheaffer plunger filler pens. Not just talking about it, but actually restoring one. I've done it at the two other shows where I did seminars this year, and it's worth your time if you're interested in these pens.

[SilverPearlVacumatic]

Thanks for the advice. I just ordered some supplies. I think this will be the ideal vac fill pen to start with, given that I can access the packing unit more easily. Even though the rest of the pen shows extensive use, the gasket is still flexible and still seems to make a seal. I was tempted to keep it, but I suppose now is the time to replace it, before I shellac the packing unit back into place.

[Ron Z]

 

 

but I suppose now is the time to replace it, before I shellac the packing unit back into place.

 

Yup. It may be OK now, but it won't be for long.

[SilverPearlVacumatic]

 

Here's a picture of the inside of the packing unit for anyone who is curious--two felt washers sandwiched between two waxy rings (I don't think they're rubber). The gasket, as can be seen in better lighting, has a metallic sparkle due to the graphite content.

Edited August 28, 2019 by SilverPearlVacumatic

[Ron Z]

You'll find a cutaway view of one of these pens pinned at the top of the repair forum.

[Addertooth]

Sometimes the head packing unit does pop out. It seems to be random, and not to be relied upon for a standard technique for repair. I had one press out when I tried to drill it out on ONE pen.

Keep in mind this is only possible on the Generation one design, which has the pen body acting as the cylinder the piston rides in. The second generation uses the pen body as a shell which slides over, and then screws down over cartridge cylinder assembly. On the second generation, the head packing unit is fused into the cylinder body; there are no known instances of the head packing unit coming out of the later design.

A hard washer (I call the dishing washer), sets behind the soft piston washer, and it "dishes" the soft washer so that air clan slip past the soft washer when the piston is pulled away from the nib. But, with this dishing, it seals rather well when the piston is pushed towards the nib. This last action creates a vacuum behind the piston, and when it gets to the wide part of the barrel (and a gap appears between the piston and the barrel), and ink is sucked up into the pen. (Ink rushes in to fill the vacuum created on the back side of the piston).

 

I realize that Ron Z gave an very authoritative answer, I only throw this in to fill in some of the nuances that a first-time Sheaffer rebuilder might not be aware of.

 

A few pictures below:

1. The ONE example where the head packing unit pressed out of a Sheaffer Tuckaway pen. Generation 1

2. An example of the "cartridge" cylinder mechanism, which is separate of the body on a Sheaffer desk pen. Generation 2 (ignore the soft washer in this picture, I was toying with an idea).

3. A drawing I slammed out this morning, showing the parts of a vac filler mechanism, which is color coded. (after restoral using the current kit, which uses O-Ring in the Head).

 

 

 

Edited August 30, 2019 by Addertooth

[Ron Z]

Technically, you're right, this is generation one. But the first plunger filler made by Sheaffer, though not under the Sheaffer name, were the WASP pens. Sheaffer made a number of changes and improvements between those pens, and the war time Triumphs. Mostly I think cost cutting and simplification of the design - but you can see the root elements, and plunger washer sizes are the same.

[SilverPearlVacumatic]

Thanks for the advice. Ill post a photo once the parts arrive and I attempt the restorationprobably a week from now.

[SilverPearlVacumatic]

I got the pen working. It's far easier when it can be serviced from the back. I had to trim the rubber seal and polystyrene ring down slightly with a razor blade so that it could fit into the packing unit which is definitely narrower than 1/4". I also placed the styrene ring into the packing unit before the seal so that I wouldn't create a chamber that would get filled with ink and be hard to clean. I think I will attempt to restore some other vac-fillers now.

[Addertooth]

Thanks to the pioneering work of those before us, repairing them involves far less guess work. Once you know how something comes apart, and is put back together AND people have sourced good replacement parts.... the job is much easier. I would not have enjoyed the repair experience If I needed to figure out all of this from scratch. The Styrene washer was a true stroke of genius, and figuring out the ideal size for the head O-Ring , as well as making pre-fabricated piston washers is a huge time saver.

[Ishinho]

Thank you so much for this wonderful and instructive discussion.

 

I would appreciate hearing any suggestions on the best adhesive option for "cementing" in the rubber seal and styrene ring into the packing unit. I've seen mention of MEK and even epoxy, but I'm wondering what works for others.

 

Thank you!

[Addertooth]

Any solvent/glue which would dissolve or soften a styrafoam cup will work (in theory). The suggestion I heard from one of the styrene ring resellers was model airplane glue. This is what I use because not only does it lightly dissolve the ring, but it has other binders which help "cement" the ring in place. The O-Ring does not need glued in place, it needs a liberal amount of the thick silicone grease around it to enhance the head seal. For the nib threads, the piston nut threads, and the blind cap threads, many people use the classical Shellac (because shellac can be softened with heat should service be needed in the future).

[Ishinho]

Any solvent/glue which would dissolve or soften a styrafoam cup will work (in theory). The suggestion I heard from one of the styrene ring resellers was model airplane glue. This is what I use because not only does it lightly dissolve the ring, but it has other binders which help "cement" the ring in place. The O-Ring does not need glued in place, it needs a liberal amount of the thick silicone grease around it to enhance the head seal. For the nib threads, the piston nut threads, and the blind cap threads, many people use the classical Shellac (because shellac can be softened with heat should service be needed in the future).

 

Thank you for this information!

[Ray-Vigo]

Correct - the black rubber o-ring should be greased. If you bought a ring specifically selected for vac restoration, it should pop into place in the unit using grease. It will seem like the black o-ring is too big at first - resist any temptation to try trimming the ring. Instead, grease the ring and use a rod to push the greased o-ring into place. The fit will be a bit tight, and that's just what you want to form a good seal.

 

The cover ring is usually the white plastic washer. The best luck I've had for softening the cover ring is Testor's model cement. I put a little around edge of the ring and let it soften just a bit, then push the softened ring down and into the cup. I let the restored packing unit assembly cure for about 24 hours before trying any further work. The white washer will also seem too big to fit in the cup unit at first. This time, the model cement or acetone or whatever you're using should soften the edge a bit and the softened ring is then pushed into place with a rod or dowel. The cover washer is not sealing the unit really - that's the job of the black o-ring. The cover washer is meant to help keep the black o-ring in place when the pen is being filled.

 

You'll know you've done it right if when you install the o-ring and the cover washer, you feel an affirmative "pop" into place when pushing with the rod. That's the tightness of the fit that will give you the seal you need.

 

There is a special tool for this work developed by Ron Zorn and sold by Pen Tooling. If you're doing more than one of these pens, I suggest buying it. The tool is meant to press the o-ring and cover washer in place in the cup unit in a firm, centered manner.

Edited September 12, 2019 by Ray-Vigo

[Ishinho]

Correct - the black rubber o-ring should be greased. If you bought a ring specifically selected for vac restoration, it should pop into place in the unit using grease. It will seem like the black o-ring is too big at first - resist any temptation to try trimming the ring. Instead, grease the ring and use a rod to push the greased o-ring into place. The fit will be a bit tight, and that's just what you want to form a good seal.

 

The cover ring is usually the white plastic washer. The best luck I've had for softening the cover ring is Testor's model cement. I put a little around edge of the ring and let it soften just a bit, then push the softened ring down and into the cup. I let the restored packing unit assembly cure for about 24 hours before trying any further work. The white washer will also seem too big to fit in the cup unit at first. This time, the model cement or acetone or whatever you're using should soften the edge a bit and the softened ring is then pushed into place with a rod or dowel. The cover washer is not sealing the unit really - that's the job of the black o-ring. The cover washer is meant to help keep the black o-ring in place when the pen is being filled.

 

You'll know you've done it right if when you install the o-ring and the cover washer, you feel an affirmative "pop" into place when pushing with the rod. That's the tightness of the fit that will give you the seal you need.

 

There is a special tool for this work developed by Ron Zorn and sold by Pen Tooling. If you're doing more than one of these pens, I suggest buying it. The tool is meant to press the o-ring and cover washer in place in the cup unit in a firm, centered manner.

 

Thank you for this detailed information. It will be very helpful. I really should invest in the special tool you mention because seating the o-ring and cover washer seem to be more difficult than I anticipated. I currently have about four pens all disassembled and ready to be reassembled once I get the packing unit squared away, so having a proper tool for the job would help tremendously.