Posts Tagged ‘removing an old sac’

Remove the old sac already!

Monday, September 26th, 2011

It happened again today.  I was working on a Mustard 51 that had a crack in the barrel, at the filler end (where else?), getting ready to do the first stage of blending the repair.  I was installing the filler so that I could check the blind cap/barrel alignment and looked inside with a flashlight to make sure that the seat was smooth because the repair went across the threads and seat inside the barrel.

I won’t go into all of the details of the repair in this post – it’s enough to say that the pen had been repaired in the not too distant past and the sac was still still pliable, though twisted into a knot.

But whomever had done that repair had not done it right.  There in the barrel, all of the way around was about an inch of dead diaphragm stuck to the barrel wall.  The cleaning that I had done to remove it from the crack had not softened it one bit.  It was stuck.

I see this quite often when a pen has been “repaired” by an amateur.  Whether a sac pen or a vacumatic filled pen, it’s not uncommon to see the remains of the previous sac still stuck to the barrel wall, pressure bar or diaphragm.  So why is that a such a bad thing?

For a sac pen there are a couple of problems.   If stuck to the barrel wall, and/or the pressure bar, the old sac will reduce the inside diameter of the pen.  The typical amateur will then grab a smaller sac, using in some cases a #16 where a 18 or 19 would be appropriate.  This reduces the ink capacity significantly, and the sac has a tendency to slip off of the section because the sac has to be stretched too much.  If it’s stuck to the section, the extra layer may make the section too big to fit into the barrel without force, and it keeps you from getting a good seal on the section.

In a Vacumatic filled pen remains of the old sac on the barrel wall can cause the diaphragm to bind as you press the plunger down to fill the pen.  If the old diaphragm isn’t cleaned off of the seat in the barrel, you’ll have an extra layer (as if you had two diaphragms stacked one on top of the other).  This will keep the filler from screwing into the barrel as far as it should.  The pen can leak, and the blind cap may not screw down as far as it should.  The typical amateur then tries to compensate by tightening the filler in even harder, which can cause barrel bulge or crack the barrel.  I’ve seen it all, and it’s not pretty.

I know that it takes a little more work to get it ALL out, but it’s worth the effort.