I responded to a thread over on PT but I see that the thread is already 3 days old from its start. Maybe the folks involved will still see it. But since I went to the trouble to write it there, maybe it would stimulate some interest or discussion here.

The object in question is the ink shut-off mechanism that was installed in Personal Point Dorics, and Coronets which was actuated by the contact of the inner cap with the exposed tab of the shut-off on the front of the section. As the cap is screwed on tight, the tab is pressed in toward the barrel. The tab is the exposed part of a shaft which at the other end has a cone shaped part sitting at right angles to the section bore. Inside the section bore there is (is supposed to be) a rubber gasket against which the cone seats blocking the flow of ink out of the barrel and into the section. These devices have the reputation as being merely a sales gimmick and many have found they do not work reliably.
Here's is a part of the patent drawing:


15 is the shut-off, 18 is the gasket

I wrote the following with some improved edits here about it:

Wahl-Eversharp Shut-Off Mechanism's did work, and they can be made to work again. I have rebuilt enough of them to know that what went wrong with them seems to have been due to 2 simple factors that people did not take care of. 1) If you do not flush your pen frequently (monthly or so), and worse, if you let your pen go dry from disuse, the solid residues from the dried ink will block/degrade the sealing action, and these solids will not always dissolve and run through the pen from
simply refilling and normal use and 2) the gasket against which the cone shaped valve seats stiffens over time (like about 5 years) and needs to be renewed.

I can not tell you how many times I have received a pen for repair from someone who got it back from a "professional restorer" only to find that the gasket is either missing altogether or is still there in its old brittle and non-sealing state usually pressed into conformity and looking like a part of the inner area of the section. In such a case replacing the gasket and making sure the inner cap is in the right position such that when the cap is screwed down the shut off mechanism is acutated deep enough to make a seal, has almost always fixed the problem.

Granted that the mechanism relies on a few spatial relationship issues being within narrow tolerances for it to work, but if I can get it to work properly, others should be able to also.

Gimmick? Of course, but a gimmick than can be made to work properly.
Wahlnut

Syd

My observation is that if it worked well it would have been continued on later Wahl models and would have spread throughout the industry. Same with adjustable nibs, although they did work better than the ink shutoff.

Thanks for your- as usual - very informative posting Syd.
I always enjoy reading & learning from your technical sound input
Francis

Syd, this is very nice information. I have two Wahls with ink shut-offs - one that is working properly and the other does not even have the spring in it anymore. It is a shame about the non-working one because if I have a choice of pen to ink up, that broken mechanism certainly makes me think twice about using it. And it has wonderful adjustable nib on it, too!
When I do decide to put ink in it, it will be fine unless I leave the pen sideways for any length of time. After that, the ink collects at the rim of the section. Not saying I would remove the shut off system, but sometimes it would be nice not to have it around. Maybe I'll send the pen in for a restoration spa one day.

Al

Thanks, Syd!

Do you have a picture of a replacement gasket, or the whole section disassembled? How do you make your replacement seals? What's the patent number on that drawing?

Questions, questions, questions...


Cheers,
Tom

Line by line, element by element, the hard won information is slowly leaking out (pun intended)...I really don't mind sharing, mostly because the key ingredient is not the materials or the tools, but the acquired skill necessary to do the job that comes only with a lot of experience in doing these things many times.

I cut them from correct size nitrile or neoprene tubing. They MUST be cut EXACTLY the right length and at perfect right (90 degrees) angle (I use a jig to get it right each time. Prior to the second (severing) cut, the leading end of he gasket is chamfered slightly by hand using a special very sharp 60 degree bit. When time permits I can take a picture of a gasket or the exploded section.

And here's the patent number: 2142532

Best
Wahlnut

Actually, there is an off-the-shelf O-ring that works perfectly, though you need to stack two of them. Get them in fluorocarbon rubber, and you won't have to replace it for decades. I don't have the reference number handy at the moment. I've thought about selling them, but figured demand would be so small as not to be worth the fuss.

Hi David,
I have a pretty good supply of o rings of many sizes (use them in auto restoration too). But, I would appreciate the reference number you are referring to just to see if it is better. In general, I have had some trouble stacking o rings in other situations. Sometimes stacked o rings in other application tended to slide or roll off of the 2 facing curved surfaces. The material you refer to should not distort, but one of the 2 failure factors cited in the Wahl-Eversharp factory repair literature is deformity Having said that, I imagine the cone valve should always press the ring into a nice circle every time it presses home, and I can not imagine that the top ring would twist or loop inward when free unless it twists, so it should work OK. making short cylinders from the tubing has worked fine though.

I would bet there are only 3 or 4 folks including me if that many who would get this deep into such specialized restorations at the present time, so you are probably right about the pretty small demand.

My latest project is winding replacement springs for the shut-off mechanism. Very small, those springs!



Syd the Wahlnut

Thanks, Syd!

The full patent information helps tremendously, as does the description of your technique. I'm guessing that the section on rod-filling versions is similar to, but slightly different from the one shown in the patent you reference (which is a lever filler). Restoring Sheaffer Vac-Fil pens for several years has taught me that there are many variations and associated challenges on even relatively simple designs.

Thanks to both you and David for engaging on this. I'm grateful for the open discussion of these techniques. There probably aren't many people (unfortunately) that will get this far into these, but when knowledge is shared, everyone benefits. It allows us to move more quickly through the "creative pen restorer" cycle of wonder and experimentation and creates better solutions (the scientific process as applied to pen restoration). Of course, this is probably why you shared this in the first place, Syd...

The neoprene tubing solution seems like a good fix. There was mention of a 5 year lifespan in the OP. Were you referring to the original seals, or the Neoprene replacements? It seems like neoprene or nitrile would last a very long time. Stacked flourocarbon rubber (or flubber, if you will ) o-rings would probably last, as David says, for decades - perhaps longer than the plastics in some of these pens. They'd also have the distinct advantage of saving a lot of time in the restoration process.

David: I'd also appreciate the reference number you mentioned. A stacked pair of o-rings seems like it would work well as long as they are not overly compressed by the section halves. In the drawing, there appears to be a small shelf on which either o-rings or tubing would seat, and which would help keep them from slipping or twisting.

Winding new springs is a worthy effort too, Syd. Engaging in this type of activity helps keep the "nut" in Wahlnut

Thanks again!


Cheers,
Tom

Zoicks! Yet another item that surely is available somewhere ready-made, but likely to take an absurd amount of diligent searching to locate.

Plenty of good designs that work well turn out to be too expensive to manufacture or service and are dropped. "Works well" is different from "commercially feasible" or even "worth it". If it worked great but didn't catch on with the public, it would not have spread throughout the industry. Why, for example, were the ink-shuttof plungers on Japanese ED pens the norm in Japan but never really caught on in the west? They worked great, but were not what people in the west were looking for.

There is also a difference between "works well" and "reliable". If the mechanism could get gummed with ink without regular flushing, it may have not fared well with the public - or the returns and repairs associated with gummed ink might have made the company drop it.

John

Very good points. Thanks for them...We seldom get around to talking about the BUSINESS of pen manufactuing. But making money is the whole end point for any business including the pen business, of course! Glad you chimed in on this.

Syd

My thinking is that if it weren't commercially feasible it never would have made it into the first pen at all. Wahl didn't introduce it to lose money. They probably did it because they were looking then (as marketers look today) for something to differentiate their product from the other guy's. As for reliability, I consider that part of working well. In fact almost anything could be under the broad rubric of working well. If I really wanted to split a hair over working well I'd say it worked well but just didn't meet a need. Plenty of inventions fit that description. Stands to reason that if there had been a relentless demand for pens with ink shut-oofs, we'd see lots of old pens with ink shut-offs.

There are plenty of products that were introduced to make money that didn't turn out in the long run to be commercially feasible - look at Parker and the T-1. They certainly introduced it to make money, but it didn't, so eventually it died (and it also had some significant flaws). Wahl could have easily done up the intial numbers and concluded it would be profitable, then found out that the labor costs were much higher than they expected, etc. The history of business is full of Concorde's.

But basically I think we agree - it may have worked, but it did not create any overwhelming demand for ink-shuttoff pens, the way that the inner cap created a revolution in pen design. Great idea, works when maintained, but not enough to catch on and make it last.

John