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How to Resac a Wringer-Type Twist Filler

(This page published September 1, 2017)

Reference Info Index | Glossopedia  ]

Fountain pen
Fountain pen
Fountain pen

Probably the easiest repair job you will face as a pen collector is resacking a sac-filling pen. Wringer-type twist fillers, such as those from A. A. Waterman, Chas. H. Ingersoll, et al., are a little more involved because they require you to work on both ends at the same time. That said, most of these pens remain a relative cinch to do. This article describes the process for an A. A. Waterman Pen, which was the originator of the concept and was also the pattern on which several other brands were based, and it gives you the critical information you need to do a Chas. H. Ingersoll Dollar Pen. As described at the end of this article, Sheaffer aslo offered a twist filler in its VACUUM-FIL sub-brand.

The three pens illustrated at the top of this page are all A. A. Waterman pens. The third pen, by way of explanation, is a Webster “Gold Dot” pen made by the National Pen Products Company for Sears, Roebuck & Company in 1941. (At that time, the rights to the design belonged to Clarence E. Barrett, who is believed to have owned National.)

Tools Required

With the exception of the thimble driver and pin punch, all of the tools and supplies used in this article are described and explained in How to Replace a Pen Sac. If you are not practiced at resacking pens, you should read and understand that article before working on a twist-filling pen.

Parts Required

Supplies Required

Cleanliness Is Next to Godliness

Pens work best when they are clean. When you have any of these pens apart, clean the parts. Soak the nib and feed in cool water until they are as clean as they will come, then soak them in the pen flush. When you cannot get them any cleaner, rinse thoroughly in cool water. Clean the bore of the section with a cotton swab dipped in pen flush. Dry the parts with a paper towel. (Make a twizzle on one corner of the towel to dry the section’s bore. ) Use a cotton swab dipped in pen flush to clean the interior of the cap. Rinse in cool water; then dry the cap, using a twizzle to dry the interior. Use a finger to plug the back end of the barrel, pour a little pen flush into the barrel, cap the front end with another finger, and shake vigorously. Return the pen flush to the bottle, and rinse and dry the barrel as you did the cap.

A. A. Waterman Pens

Because of the way A. A. Waterman built its twist filler, you will need two special tools.

The first special tool for the A. A. Waterman is a thimble driver. Starting with an inexpensive " (3 mm) flat-blade screwdriver, grind the business end of the blade to a narrower point. Then use a stand-mounted rotary tool with a cutoff wheel to grind both sides so that the blade assumes a diamond-shaped cross-section with sharp edges.

I recommend using a 150-grit diamond wheel on your rotary tool. The standard Dremel-type cutoff wheels are prone to shattering when pressed sideways. You can reduce this tendency, but not eliminate it, by stacking two or three cutoff wheels together on the mandrel. The diamond wheel will not shatter, and it will also cut faster.

As shown here, the finished blade should have a cross-section similar to that of a double-edged sword or knife):

Thimble driver
If you do not yet have a mounting base that will hold your rotary tool, you can build one (or, if you’re not a woodworker, ask a friend to build one for you). Plans and instructions for the base I use at pen shows can be found in How to Build a Nib Grinding Station. This base, being made of wood, is quite light, and you might need to screw or clamp it to your workbench.

The second special tool is a pin punch for driving out a wire pin in the pen. (This punch will serve you well for driving out the pins in other pens.) The photo below shows my punch. Make the tool from a 2" (51 mm) length of " (13 mm) hardwood dowel and two pieces of stainless steel music wire. One piece, a 1" (38 mm) length of 0.025" (0.64 mm) wire with its end nicely flat and perpendicular to the wire’s axis, is the punch. Drive that piece of wire into a same-sized hole drilled into the end of the dowel, leaving about " (13 mm) exposed. (If the hole you drilled isn’t deep enough, you can cut off the excess and true up the end after you finish the rest of the procedure.) If at all possible, do the drilling on a lathe; it’s almost impossible to hold things straight enough by hand. The other piece is 0.032" (0.8 mm) wire, and it goes through a same-size hole drilled laterally through the dowel to serve as a backstop for the punch. Drill this hole with extreme care to ensure that you line it up with the punch wire. Insert the transverse wire and then form one of the wire’s exposed ends into a square U shape and pound it the rest of the way into the dowel to keep it in place. Grind the last exposed end off flush with a rotary tool.


I use a jeweler’s forming block as a steady rest when I’m knocking pins out of pens. Forming blocks come in different sizes and shapes. The one I use is flat, about 1" (25 mm) thick and about 4" (102 mm) by 5" (127 mm), with half-depth round grooves of various sizes cut across it on both sides.

Forming block


The picture below shows how to knock out the steel wire pin that passes through the filler knob to secure it to the part that holds the sac at the back end of the pen. (The patent drawing calls this part a “shank,” but I shall call it a thimble to avoid confusion with the section’s shank, described later.) The pin passes through the knob very near the end of the knob that is adjacent to the barrel itself, and it is usually secured at both ends by black wax. The hole extends all the way through the knob, so it does not matter which end of the hole you find.

Knocking the pin out

Once you’ve found the pin’s hole, lay the pen barrel into the most closely fitting larger-size groove in the forming block or, if you don’t have a forming block, on a flat surface such as the top of a wood block cut from a 1×4. Use blue painter’s tape to tape the barrel down securely with the knob hanging a little over the edge. As you’re taping the pen down, orient it with the pin through the knob aligned vertically so that you can drive it out. Line up your pin punch with the end of the pin, and tap with the jeweler’s hammer. Check to see if the pin has moved, and repeat the careful taps until it does move. Then you can drive it out. If it seems utterly unwilling to budge, turn the pen over and drive the pin from the other end of its hole.

With the pin out, unscrew the knob from the thimble. Note that the knob screws onto the shaft with a left-hand thread. Turn the knob clockwise to unscrew it! You might need to use a little heat to get the knob to move, but once it is loose, it will screw off easily.

Next, use section pliers to remove the gripping section. Two section pliers, as shown in the photo below, will work better than one, but if you have only one, use a rubber gripper square on the barrel. The section is a friction fit into the barrel. Try “unscrewing” the section as if it were threaded (left-hand thread). If it refuses to turn, it might be shellacked in place. Apply a little heat and then try turning it. If it still fights back, apply heat again and try rocking the section carefully back and forth until you hear a ticking sound; that sound indicates that some of the shellac has let go. Rotate the pen 90° and repeat the rocking action. You might hear another tick, or the section might now come free. Keep working at it until it is free, then remove it.

If your pen has a threaded cap, it probably has a very short gripping section. The section does not include the threads for the cap; it is only the part between the threads and the end of the pen body from which the nib extends. (If the pen is a hard rubber Good Service branded pen or a celluloid Webster or Gold Medal pen, then its section should be of ordinary length.)
Removing the section

Remove the sac (or the pieces of it) from the section and thimble, and clean off any remaining bits of rubber and sac cement.

Now cut the new sac to the proper length. The drawing below shows what you will need to measure to determine the length. Measure the length of the part of the thimble on which the sac mounts (the nipple) and the length of the portion of the section that mates with the inside of the barrel (the shank), then use the thimble driver to screw the thimble into the barrel (left-hand thread), then reinstall the knob. Insert the pin punch into one of the holes in the knob and screw the knob back and forth while you hold the thimble with the driver, until the punch goes into the hole through the thimble and then through the hole on the other side of the knob. Screw the knob down (left-hand thread) gently finger tight — do not force it. Insert the wooden skewer into the barrel until it stops against the end of the thimble. Do not let it slip past the thimble or into the cup-shaped hole in the thimble. Mark the skewer with a pencil right at the edge of the open end of the barrel, then remove the skewer. Remove the knob and thimble again. Add the thimble nipple length (B) to the barrel depth measurement (C), then subtract the section shank length (A). The result is the sac cut length. Cut as described in the previous bulleted item, being as accurate as you can — but do not cut the sac longer than the measured cut length.

Cut length diagram
A much simpler way to make the measurement would be to just lay the section, barrel, and thimble on your work surface in what looks like the proper relationship and measure the distance that way. Do not succumb to the easy way out. I have found by experience that this method does not consistently produce good results because laying out the parts in the exactly correct relationship, and keeping them there without fastening them down, is extremely difficult.

Knock the nib and feed out of the section in the usual way, using a hammer and punch with a knockout block. The photo below shows clearly how short the section is in an A. A. Waterman with a screw cap.

Knocking out the nib and feed


Do not reinstall the nib and feed until instructed to do so. If you install them before that point, reasoning that it is easier to install them in the section while it is separate from the barrel, you will have to remove them again, and that will probably also entail removing the new sac.

Attach the sac to the section and the thimble. If you had to cut the end of the sac that was originally closed so short that there is still a tapered area, attach that end to the thimble’s nipple. The resulting assembly should look like the photo above that shows how to measure a sac that is still whole. Set the assembly aside overnight so that the sac sac cement can dry thoroughly.

It is understandable that you would prefer to do the job and get it done, but the overnight drying time is vital, especially if you are using fresh sac cement.

Coat the sac lightly with talcum powder. Insert the thimble driver through the section’s bore, and engage it with the hole in the end of the thimble. Without stretching the sac, grasp the gripping section and the thimble driver firmly together so that they will behave as a single piece. Insert the section/sac/thimble assembly into the barrel. Screw it in counterclockwise (left-hand thread.).

Iserting the sac assembly

Continue screwing the assembly into the barrel, turning the driver with the section so that the section does not rotate around the driver or slide up and down on the driver’s shank. Although the section is not threaded, if you do this right, it will appear to be screwing into the barrel as the thimble screws in to the other end of the barrel.

When the section comes up against the end of the barrel, the thimble should project far enough out the other end so that you can see the hole for the pin that secures the knob. If not, screw a little farther until the hole is just far enough past the end of the barrel that you can screw the knob onto the thimble and align the holes through the two parts. If necessary, use the pin punch to assist in aligning the holes.

Realigning the holes

Reinstall the pin. Position it so that it is midway between the two ends of its hole. Force beeswax into each end of the hole, using enough that a small bump of the wax sits above the surface. Heat the knob very slightly, just enough to begin softening the wax, and press the wax firmly into place with your fingers. Clean off the excess wax and polish the knob with a piece of clean 100% cotton flannel. (Do not use a synthetic or a synthetic blend; the fibers can be harder than the material of the pen, and they can scratch and dull it.) If you like, you can dot each of the wax plugs with a black permanent marker to conceal the wax.

Applying beeswax to the holes

If the knob is not gently finger tight against barrel, back it down using the thimble driver, turning the section with it, until the knob just touches the end of the barrel. Now screw the slightest it further, less than turn farther, so that the knob will be seated perfectly when it is gently finger tight. Check inside the barrel, using a bore light, to see that the sac is not twisted, and make any necessary adjustments by rotating the section slightly without rotating the thimble.

Reinstall the nib and feed, and align the nib properly. The pen here, a clipless vest-pocket model, is ready to join the collection.

Finished vest-pocket pen

Chas. H. Ingersoll Dollar Pens

Between 1924 and the early 1930s, the Chas. H. Ingersoll Dollar Pen Company used two different versions of the back-end works:

The later version, which appeared on Bakelite pens starting in about 1927, works exactly like the A. A. Waterman design except for one little thing: the filler knob is right-hand threaded instead of left. And this pen does come apart slightly differently. It uses a thimble that is a cap nut, and the cast-metal knob has embedded into it a screw that screws into the thimble. The thimble has a screwdriver slot, so that you can use an ordinary flat-bladed screwdriver.

Fountain pen
Fountain pen

Disassembly and reassembly are straightforward. The measurements for sac length are the same as with the A. A. Waterman, as is the basic reassembly technique. Screwing the thimble and the knob together tightly holds the assembly very securely.

The earlier version made its début on Ingersoll’s first metal pens, and it remained in production through about 1927, in which year the company took a short fling with celluloid before settling on Bakelite.

Fountain pen
Fountain pen

On a celluloid pen, resacking is very easy and straightforward. On a metal pen, it is more involved because the metal section is pressed very tightly into the metal barrel, and getting it out can be quite difficult. Here is a layout of the parts in the metal version:

Ingersoll parts
Ingersoll’s metal pens were pressed together with a very tight force fit. At the joints, the inner part puts huge tensile stress on the outer part, often splitting it. Many (possibly most) of these pens have cracks at the front end of the barrel or at the end of the section, or both. It is possible to repair these cracks, but it is not easy, and the results are usually unacceptable cosmetically.

Heat and two section pliers, and a lot of wiggling and pulling, will eventually succeed in getting the section out of the barrel. Further complicating the task is the fact that the sac is cemented to a hard rubber inner section, and the proximal end of the sac is down inside the end of the metal section:

Ingersoll front

Removing the old sac remnants entails a fair amount of digging with a dental pick to get all of the bits out of the gap between the two sections. Attaching the new sac (a No 22) to the section requires you to apply sac cement to the interior of the sac and then install the sac over the inner section and push it down into the gap.

At the back end of the pen, there is no thimble as such. Instead, the back end of the sac is cemented to a simple hard rubber plug. There is a hole in the outer end of the plug, and there is a matching hole in the back end of the pen’s barrel. For the knob, a decorative upholstery tack is inserted through the hole in the barrel and into the plug, and then the plug is pushed down onto the tack (but not all the way to the end of the barrel). When the pen is assembled, there is about " (1.6 mm) of play at the end. The tack rests against the end of the barrel but can be lifted far enough to allow the insertion of a small screwdriver blade to pry the tack free for sac replacement.

Partway through the product life cycle, Ingersoll added a conical washer between the tack and the flat back end of the barrel; this washer made the mechanism work more smoothly. The washer was later eliminated by the simple expedient of making the end of the barrel conical. The illustration below shows the version that had the washer.


If you have a machine lathe, take the time to modify the section to eliminate the risk of cracks. Turn down the shank of the section a couple of thousandths of an inch (0.0010" = 0.0254 mm) so that it fits s little less tightly in the barrel (but still tight enough to require a little force, not slip-in loose). Then knock out the hard rubber inner section and turn it down in the same manner. It, too, must be a press fit, not loose.

The fit of the inner section is critical; if it’s too loose, installing the nib and feed will force the inner section into the interior of the pen. You get only one chance to do this right; turning the inner section too far will ruin the pen.

Sheaffer’s VACUUM-FIL Twister

From about 1934 until America entered World War II in 1941, Sheaffer produced pens under at least two sub-brands, WASP and VACUUM-FIL. Among the pens branded VACUUM-FIL was a very simple (and attractive) celluloid twist filler:

Fountain pen
Fountain pen

This pen, while good looking, is troublesome to resac. The section installs into the barrel with a friction fit like that in an A. A. Waterman pen, but there is no special mechanism at the back to allow easy assembly. The transparent amber twist knob shown in the photo is threaded into the barrel end (right-hand thread), with a nipple for the sac. There are small heat-stamped arrows on the knob and the barrel to show correct alignment when the knob is screwed all the way in.

To resac the pen, remove the section assembly and the knob. Determine the length for the new sac by using the method described earlier for an A. A. Waterman with a sac that is no longer whole. Cement the sac to the section nipple, and let it dry overnight. Install the section/sac assembly. Using tweezers or alligator forceps, fish the loose end of the sac out of the back end of the barrel. Pull out about " (13 mm) and clamp it with the hemostat.

Cement the end of the sac to the knob’s nipple (photo below), and set the pen aside to dry overnight. Remove the hemostat carefully, guiding the knob so that it gently aligns itself with the barrel. (Do not simply let it snap into position, or you might find yourself repeating the cementing operations.) Screw the knob all the way in, turning the friction-fit section along with the knob to keep the sac from becoming twisted. Then turn the section less than turn more to put just a little tension on things.

Holding the sac with a hemostat

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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