Help! Repair Advice On Chipped Cup For Vacumatic Pump Unit

March 18, 2015

I had a bummer of an experience last night. Riding on the high of successfully restoring a Vacumatic Major with a nice flexy nib, I ventured ahead to restoring a beat up Parker 51 I picked up from the bay.

The most challenging of these restorations is removing the pellet inside the cup of the pump unit. I managed with my Dremel and a dentist pick, but in the process of inserting the replacement diaphragm, a small portion of the cup broke off. It's a tiny section, approximately triangular shape, from the lip of the mouth down less than half the side of the cup. I was devastated as everything else was going so well. The only silver lining is that the diaphragm is securely mounted to the cup.

I tried to brainstorm some solutions, and it boils down to:

(1) Superglue the broken off portion being careful not to get any glue on the diaphragm. My thinking is that the cup will be covered by the rolled up portion of the diaphragm. As long as it does not have to endure excessive stress, the cup will manage to hold onto to the pellet for as long as I will have/use the pen. I could reinforce and help maintain structural integrity by wrapping the cup with teflon tape.

(2) Just wrap the cup with teflon tape to help maintain it's shape (in the process I could place the broken bit on there without gluing). As long as the increase in dimensions is kept to a minimum, such a procedure will not hamper the fit and function of the cup.

The above may just be a stop-gap measure, but I would like to hear from the more experienced among you as to how best to go about overcoming this little accident. If needed, I could buy another pump unit. However, I do not know where to source this besides parts pens from the e-bay.

PS - Sorry for no pics.

March 18, 2015

If the cup is indeed holding the pellet without the chip, then don't try to re-attach the chip. You should probably apply a little micromesh to it so that it has rounded corners that won't poke holes in the diaphragm.

There are other approaches, though. There are instructions for making a cup from an otherwise perfectly useless object, and you can also buy newly-fabricated cups which are rather closer to original spec.

March 18, 2015

Thank you Ernst. On a related note, if I was to replace the cup, what is the best procedure for removing the old cup?

March 18, 2015

Thank you Ernst. On a related note, if I was to replace the cup, what is the best procedure for removing the old cup?

Not Ernst, but very carefully with a #11 Exacto or similar blade, very sharp. Be careful not to damage the slit in the plunger shaft that takes the spring. Many times they are very fragile.

Let us know how it goes.

Glenn

March 18, 2015

I would use epoxy to try the cup repair.

Glenn

March 18, 2015

Not Ernst, but very carefully with a #11 Exacto or similar blade, very sharp. Be careful not to damage the slit in the plunger shaft that takes the spring. Many times they are very fragile.

Let us know how it goes.

Glenn

What he said. Keeping it warm will help.