One of today’s projects was a lovely pen, a Tibaldi Modello 60 that was here to have its nib smoothed and adjusted for good flow. But there was a problem. The piston wouldn’t draw ink, so there was no way to fill the pen to test its nib.
Faced with the choice of finding and fixing the problem or sending the pen home without adjusting it, I disassembled the pen.
It shouldn’t take you too long to spot the problem, At the bottom of the picture is the piston, with its O-ring seal removed, and you can see that the flange at the end of the piston head is broken.
The flange had actually broken exactly across its center, at the mold seam (where the two haves of the mold in which it was made came together). It broke because the design of the piston is, I think, wrong. Instead of compressing the O-ring between the piston’s shank and the bore of the clear barrel liner, this design compresses the O-ring between the two flanges on the piston, allowing it to float freely around the shank. The O-ring, in resisting that squeeze, forces the two flanges apart, and it broke one of them.
Absent a replacement part, the only possible repair is to create and install a replacement for the broken flange. (And given the cause of the original failure, simply replacing the failed part doesn’t seem all that attractive anyway.) So the first step is to remove the remains of the broken flange, cut a piece of plastic sheet for a new flange, and find an appropriate method of fastening the new flange to the piston. The fastener I chose was a brass 2-56 flat-head screw. To protect the screw from ink in the pen, I would apply a button of epoxy over the screwhead after assembling the parts. Here’s the cleaned-up shank with a square of white polystyrene and the screw.
To make a tapped hole in the end of the piston shank, I chucked the shank up in the lathe, protecting it by inserting it into a length of appropriately sized tubing, and drilled a No. 51 hole for the tap. The hole had to be deep enough that the screw could seat all the way down to its head.
I then tapped that hole using a 2-56 tap in a pin vise, making sure the brass screw would indeed screw all the way in.
After making a conical hole in the middle of the plastic square, I assembled the three parts.
Having assembled the plastic square to the piston, I cut away most of the extra plastic and then chucked the assembled piston up in the lathe again to finish turning the new flange to its final size.
Finally, I greased the O-ring lightly, assembled it onto the piston, and covered the exposed face of the piston with epoxy.
Tomorrow, after the epoxy has set completely, I’ll put the pen back together and complete the nib work that it came here for in the first place. It’s a really good feeling to know that a pen has been saved that might otherwise have caused its owner great sadness by untimely dying.
