Many moons ago I promised to post an article on the repair of the innards of the Wahl Oxford Twist Filler Pen. This pen seems to have gained the reputation of being one of the more difficult to make work again. While some of the reputation is true it is not completely impossible either. Any one with a copy of Frank DuBiel's Fountain Pen Repair can easily find the pages where the process is described and the drawings help a lot too. Here is a copy of the diagram that is most germane:
Diagrams are nice but sometimes it is easier to see the real components as they appear to the repair person:
Now attach the closed end of the sac to the square cup in the inside of the twist fill mechanism with Here is the pen mostly dis-assembled with the barrel innards except for the permanent central grommet and the tempered steel securing washers that hold the grommet in place.
The twist mechanism also comes apart in 3 pieces - the red plastic twit fill knob, the threaded twist fill housing and the twist fill cup and threaded shaft that the red knob screws onto. It is necessary to take the twist mechanism apart to do the repair. It will be necessary to remove the red knob prior to re-assembly in order to screw the housing back into the end of the barrel without twisting the sac as that is done. (the housing takes about 3 complete revolutions to seat and the sac if binding, will get twisted which must be avoided in order for the twist filler to work.)
The size of sac that you see loose, above is not cut to size yet. Also the sac above was chosen at random based on what I had the most of at the time. That it is necked, is of no significance here. As a matter of fact the neck was discarded in this case. The sac diameter to choose is whatever you have that is just smaller than the pen barrel (small enough that the sac does not rub against the barrel inner wall). The approximate length of the trimmed sac will not be more than approx. 1 1/4". So choose a sac where the loss of excess sac when trimmed will be minimized. Getting the right length is tricky as it must be measured with a depth gauge from the rear of the open barrel to the central grommet. but the rule of thumb is to cut the sac such that when the sac is secured to the hollow, threaded screw head, the sac end is 1/16" recessed inside the barrel end. Attaching the sac to the screw head is a little tricky because the surface area of the screw head sides is not very great. Use shellac. I have found that if the sac is the right diameter it will need to be stretched a little to go over the screw head and cup slightly beyond the screw head as shown in DuBiels diagram above. This tension helps to secure the sac to the screw head better.
Here is a picture of the exploded parts with the sac in place on the threaded screw head and the closed end of the sac attached to the little square swivel cup in the inside if the twist fill mechanism. I will insert another picture of the exploded twist fill mechanism later on.
Next one inserts the sac and hollow screw unit into the back of the pen barrel. Then the threaded nut goes into the front of the barrel. The threads of the screw will protrude beyond the central grommet so that the nut can be screwed onto the screw pulling the screw head and sac snug against the central grommet. The nut has 2 grooves cut into it on one side. This allows the use of the split screw-driver that Father Terry sold to many folk. But you can make your own if need be. Only when this is done should you attach the closed end of the sac to the twist fill cup and shaft part of the twist fill mechanism. They used shellac at the factory, but today we use super glue gel because it sets quickly and seems to last longer.
You can insert a thin dowel all the way from the section end of the barrel up through the hollow threaded screw into the sac to apply pressure to the sac end while gluing the sac end to the shaft cup. When this is done, the twist fill shaft will stick out of the back end of the barrel.
Slip the twist fill housing over the shaft, and screw it into the barrel end. When seated properly the housing will sit slightly below the back barrel lip. It will be necessary to push the twist shaft in a little when screwing in the housing as it tends to bind and then the sac gets all twisted in the process. When seated test that the sac is not twisted with the dowel. When that is done re-attach the red twist fill knob. If done correctly, you will see that the twist fill knob can be rotated about 350 degrees and will snap back to starting position for another twist. It snaps back because of a tiny circular spring inside the back end of the twist fill housing and the rubber sac's "memory" working together. Each twist expels one sac's worth of air and when released draws in one sac's worth of ink. When the sac untwists, the ink flows up through and overflows the end of the the breather tube flowing downward around the breather tube and through the hollow screw into the barrel cavity reservoir. It may take more than 5 twists to fill the resevoir as each twist can only add it's contribution to the reservoir limited to whatever the internal volume of your sac actually is.
In the interest of time, I am posting this article now but will return to edit it and add more information a little later.
Hope this proves interesting to you all.
Syd the Wahlnut
Edited by Wahlnut, 20 January 2008 - 19:34.