Wednesday, November 25, 2015

Repair Tutorial: Fixing a Typical Stripped Mechanism

I’ve had this Waterman pencil laying around for awhile.


It’s a nice “Thorobred” pencil in a color I had not seen before.  The “red and gold” celluloid was cataloged in 1933 on the Waterman 91 (pen guys would call these “Waterman 92 pencils”).  However the 1936 catalog doesn’t show this color in use for the 91V or 93V (“Waterman 92V pencil” or “Waterman 3V pencil,” respectively).  And I’ve never seen one.

However, the mechanism was shot – I could tell the tabs on the lead carrier were stripped.  I got as far as wiggling the mechanism free from the barrel, but until last weekend I didn’t find time to fix it.  When I did, I thought you might like to see how it’s done.

Before you do anything, including pulling the mechanism out of the pencil, spend some time making sure that the mechanism is actually stripped.  If it isn’t, there are a couple other possible issues, all of which can be fixed without pulling things apart:

1.  A lead jam.  Start by trying to advance the mechanism all the way forward and all the way back.  If you hit a dead stop in either direction, the problem is a simple lead jam, not a stripped mechanism.  Caution: stripped mechanisms occur when someone has tried to force the mechanism when there’s a lead jam.  If the mechanism turns until it bumps into something, STOP and clear the jam, then try again.

2.  A mechanism that is “skipping the track.”  Some pencils were designed with an anti-stripping feature, which allows the mechanism to continue to turn when the mechanism reaches its mechanical limits.  While the mechanism may be stripped, it might also just be jammed at one end or the other of the mechanism.  You can tell this is the case if you hear or feel a faint clicking sound as the mechanism is turned.  If you think this might be the problem, first use a paper clip like a piece of lead, pushing gently up into the pencil as you retract the mechanism to see if you can ease the tab back onto the track.  If that doesn’t work, the mechanism might be stuck at the top end - make sure there isn’t any lead left inside, then try to access the back of the mechanism and force a paper clip into the top end while trying to advance it.

Only after exploring these two possibilities should you remove a mechanism, because there’s a strong possibility you will crack or break the barrel.  These are typically press fit into the barrel with enough friction to hold and operate the mechanism.  With a combination of wiggling, pulling and (if you can get at the mechanism from the back end) pushing, sometimes aided by heat, you can usually get them out.

Now, examine the mechanism closely.  At the rear end, you’ll see a retainer washer.  Sometimes you’ll find a two-part washer, but in this case, Waterman just used one thick one.


The back end of the drive tube is flared a bit to hold the retaining washer in place.  To remove, use a small pair of pliers to crimp that flared part down so the washer can slide off.  Use pliers without teeth on them to reduce the risk of deforming the drive tube.  Here’s what it looks like when you’re ready to remove the washer:


Watch out - that retainer washer will be tough to coax off without launching it across the room, but once it’s off, the spiral will spin right off of the tube, and you’ll be able to remove the lead carrier from the back end.  You might need to open the end of the tube a little to get the carrier out, depending on how much you crimped it down to remove the washer:


On a typical propel-repel mechanism, the lead carrier consists of two parts, each of which has a metal tab which sticks up and engages the track in the spiral.  The outer carrier, which has the forward tab, is the tube the lead fits inside.  The rear tab is attached to a pin, so that as the mechanism reaches its forward limits, the outer tube remains stationary while the spiral moves the rear tab forward to eject any last crumbs of lead from the outer tube.


In this case, our tabs have been partly sheared off.   Sometimes they are simply bent down and it’s possible to bend them back into shape, but I only do that when the mechanism has unique features and I don’t have a suitable donor.  Structurally, the metal has been compromised and will never be right again, and it’s best to replace these.  I keep a supply of junker pencils around for that very purpose:


These crappy plastic-tipped pencils are perfect for the job: they never worked well to start with, the tips are almost always chipped away, and the plastic usually shrank much faster than the celluloid barrels inside, so they are easy to pull out without much time or effort.  NOTE: make sure your donor mechanism uses the same diameter lead as the one you are repairing.


Fortunately, since they didn’t work all that great, the internal pins never saw much wear.  Here you can see the same basic innards, with pristine tabs engaging the spiral.  Note that this one has a two-piece retaining washer.   I removed these washers and kept them for future use some other day and removed the lead carrier.  Side by side, it’s easy to see why my Waterman wasn’t working:


I slid the lead carrier into the drive tube of my Waterman.  Once the carrier clears the rough part at the top of the tube, it should move freely up and down the channel.  If it doesn’t, use a paperclip, pin or toothpick to clean out any obstructions in the channel, and lubricate with a tiny amount of PB Blaster (like WD-40, but it doesn’t coagulate lead dust).  Be sure to wipe off any excess lubricant, because petroleum products and celluloid don’t play well together.


Next, slide the spiral back on.  When you reach the tabs on the lead carrier, screw the mechanism over them, being sure to engage the tabs.  Don’t force anything - it should simply engage the tabs and screw on.


Once the spiral is all the way forward, twist it to see if the tabs properly engage the spiral and move back and forth as you twist:


Work the washer back onto the end, making sure the spiral is held securely against the nose of the pencil:


And use your pliers to flare the end apart again to secure it.


That should do it, but put a piece of lead in and try it before you put the mechanism back in the pencil.  Better to know now whether your mechanism is working in practice rather than just in theory:


Last, press the mechanism back into the pencil.  This may require a pen press or some similar tool that can apply controlled pressure to the part.  Once it’s in:


There you have it.

4 comments:

Michael Quitt said...

Great article, Jon...thanks for taking the time to take the pics and to teach us how to repair these pencils...!!

Andrea Kirkby said...

Fantastic! great repair information and lots of pictures. I hope to have some of my vintage pencils up and running with this info. Thanks so much for writing it all up.

Oh, and that is one luscious Waterman.

Martha said...

Thank you so much!

David Nishimura said...

I'd also advise warming the front of the barrel when reinserting the mechanism. It's all too easy to split that thin barrel mouth if it hasn't been de-embrittled with a bit of heat.