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Vintage Onoto Repair Help


pieemme

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I have been through a long process of restoring a vintage Onoto 6233. It took me longer than expected mainly due to my trial & error learning process. I had to order my spares twice through Roger Wolfe's custompenparts.co.uk. I also am most grateful to Richard Binder for his instructions, both from his book and website.

 

In spite of this guidance, I am not entirely at ease with this plunger mechanism, which I find in Onoto pens unnecessarily complicated in design. I replaced the rod, which I had broken in my learning process and followed Roger Wolfe's instructions in identifying the proper position for drilling a hole through the rod. With the section opened and the plunger in working order, I hear a sharp pop when the pluger reaches the end position, therefore I believe than air tightness is not an issue. What I am not too sure about is the correct position of the plunger tip, once the plunger knob is screwed in. Should it rest against the feed assembly or should it leave a gap? I've read somewhere that the Onotos have some safety feature to prevent leakages and that one needs to partly unscrew the plunger knob when writing.

 

I hope some Onoto expert is reading my message and willing to help.

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The base of the feed is curved, allowing the top of the piston rod to sit comfortably within it. This creates "a seal" that prevents ink flow to the nib (the safety feature). The knob is then turned 1/2 a turn before use, releasing the seal.

 

So to answer your question they should abutt one another.

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Thanks for this confirmation. I have just started using it and wasn't sure whether the pen was not taking in ink or there was some kind of block. I find this design a bit gimmicky. I really miss an ink window. What I hate about lever fillers too is never knowing how much ink is left.

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Buy decent 100g scales. Measure it empty, then any time you want to know ink level weigh it again. The difference is remaining ink in mL. In theory I use this for more than a dozen pens without an ink window but in reality I mostly just let them run out. I have other pens inked.

 

It is unclear why you consider a vacuum filler gimmicky. Its operation is quick and simple.

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I suppose I would not be purchasing a Model T Ford if I really wanted an 16 valve, turbo charged, electronic ignition, soft top, bimbo pulling, super car.

 

You are looking at a state of the art pen from the time of the great war. Enjoy it for what it is.

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I consider Onoto's plunger filler mechanism as gimmicky. I mean it takes a long road to deliver what any vacuum filler does. Just think of the idea of using fixing pins for the plunger design, let alone the number of parts involved in the rod/plunger assemby. I would call it a "Grande Complication" (this was the name of a Swiss watch). Compare this to the straightforward and matter of fact desgn of a Pelikan m400 or a Montblanc 342. Ink windows, reliable long lasting mechanics, no corks involved, etc.

 

I chose to get an Onoto to satisfy my curiosity but am not overly impressed by it.

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I suppose I would not be purchasing a Model T Ford if I really wanted an 16 valve, turbo charged, electronic ignition, soft top, bimbo pulling, super car.

 

You are looking at a state of the art pen from the time of the great war. Enjoy it for what it is.

 

You're absolutely right: there is a degree of pleasure in self inflicted pain in using these pens. In fact, I love these vintage pieces and strongly hate cartridges, ball pens and rollers. But, as a daily writer, I'm much happier with my Swans and vintage MBs.

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there is the legendary tale whereby a customer of Arthur Twydle - whose Onoto had just been repaired - complained that his pen wouldn't write - to which the answer from Arthur was " have you turned it on?" i.e. the shank needs half a turn anticlockwise, thus backing off the piston and allowing the ink to flow.

 

Probably too late in the day now for the op, but there is the 'Onoto Pen Repair' manual, which has much guidance on most aspects of construction and repair - I think it was inexpensive - something like £10 - £12.

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I'm still having an issue with filling my pen. When I push down the plunger, there's a clear bubbling in the liquid, ink or water, but the pen is not sucking in the ink. In fact, it only fills when the plunger goes up, like a piston filler and empties when the plunger goes down, instead of the other way round. Does this mean that the problem is with the o-ring on the other end? Or any other cause I may have overlooked?

 

I followed Richard Binder's method

 

http://www.richardspens.com/index_m.html?page=ref/repair/onoto_filler.htm

 

i.e. no cork washers, just an o-ring with a space filler underneath the packing retainer ring.

 

Any ideas?

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although not my area, it does seem that optimum function relies on the two seals - the O ring on the rod, and the plunger washer that forces out the air and creates the vacuum. Are you getting the 'pop' sound when the vacuum is released on a dry down-stroke? The rod mustn't be damaged, if so this lessens the power of the vacuum apparently, and the O ring seal must be a good fit on the rod. Am sure you've done all the necessary cleaning etc., so.....

With the rod fully withdrawn then go down slowly - the rod mustn't foul the cone at the rear of the feed prematurely.

Am I missing the point or is it the case that the up-stroke must be completed free of the liquid - then you dip the nib and push down to create the vacuum until the plunger washer passes the vacuum break point when, in theory, the ink will be pulled up into the barrel which by now should have reduced pressure.

In principle, if the feed and nib are clean and clear and allow air/ink into the barrel, and if both washers are seated and correct size and the rod isn't damaged, then things should work.

 

It all sounds so simple, but I admit to not having attempted a renovation of said models although I do have a couple that have promised myself I will repair one day!!

 

Can only wish you luck. :)

Edited by PaulS
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Am I missing the point or is it the case that the up-stroke must be completed free of the liquid - then you dip the nib and push down to create the vacuum until the plunger washer passes the vacuum break point when, in theory, the ink will be pulled up into the barrel which by now should have reduced pressure.

 

Can only wish you luck. :)

 

That was my immediate thought on reading the reply. (The nib should not be inserted in the ink until the piston rod has been fully extended).

 

By coincidence I have replaced the seal / corks in three onotos this afternoon (corks not o-rings), first time for perhaps 6 months, it is a relatively straight forward process.

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Listen for a clear pop when the plunger passes the break point, then wait a few moments to give the ink time to enter. If the O-ring is not a good fit with the barrel then you will not get that clear pop, and in any case an O-ring is unlikely to perform as well as a cup washer as originally fitted by Onoto. Must be something about good design on their part, just like the contrarily threaded ends to avoid unscrewing, and the pinned parts to permit perfect adjustment of the plunger rod for shut-off before fixing. One other point is not to push down the rod slowly (nor clumsily to break it ). The vacuum will always be imperfect, so pushing down smoothly but not slowly will maximise the available vacuum. I presume the packing seals at the top are good?

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Thanks northlodge and PaulS for your diagnoses and suggestions. I am currently travelling and unable to do much work around my pen. Just one thought: when I had assembled my plunger with the washer in place and the o-ring in the back, the plunger was making a sharp popping sound when reaching the bottom of the barrel. However, when I assembled the rod with its knob, locating the locking position and fixing the pin, there was no more pop, no more snapping sound to be heard. Because the plunger was stopped before the popping point. Now, is this how it is supposed to work? When assembling the new rubber washer I was in doubt, where to put a ring I had found on the original plunger. I first placed it below the washer, but then noticed that, after some time the washer was sliding out if place, up the rod. So I placed the ring above the washer to help keeping it in place. I enclose a picture with all the parts involved, including my original rod. In the picture you can see the o-ring, on the farmost left, the packing ring seen sidewards, then the rubber washer, with its supporting ring right below it and, finally, this little ring I had found on the original rod, for which I haven't been able to find any use. My doubt, at the end of the day, is: could it be that this smaller ring has an impact on the washer position and hence on the function?

post-110538-0-61730800-1490935875_thumb.jpg

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Did you confirm that the rod length in position for pinning to the cap reaches the shutoff when closed, before replacing the section? If not then it will not shut off, and more, it sounds as though the rod lacks sufficient length to complete an adequate fill if mis-placement of the washer is enough to prevent it clearing the internal barrel lip.

 

Onoto pen data specified the rod in a 6233 to be 71.2 mm but they can vary a little in repair. Do you have a measure of the length in your case?

 

I am sending you an explanatory PDF which may add to the information you have already obtained.

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Thank you so much praxim, most helpful. I'll check this out as soon as I am back.

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This might have helped: https://www.fountainpennetwork.com/forum/index.php/topic/98610-onoto-plunger-filler-repair-restoration-help-needed/

 

You can see the parts you should have and how they should go together.

"Truth can never be told, so as to be understood, and not be believ'd." (Wiiliam Blake)

 

Visit my review: Thirty Pens in Thirty Days

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Compare this to the straightforward and matter of fact desgn of a Pelikan m400 or a Montblanc 342. Ink windows, reliable long lasting mechanics, no corks involved, etc.

 

 

That's not a fair comparison ... those piston fillers are the result of learning what works, what doesn't work over the years.

 

(Plus I'm pretty sure that vintage Pelikan piston fillers used treated cork for their seals)

 

-k

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Thanks, I remember having seen these pages at some stage. I haven't so far found out anything different from whar I did. In a way, I wish I had. But I fear I'll have to dismantle my pen again and won't bet on my fixing pin's survival after another extraction.

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Thanks, I remember having seen these pages at some stage. I haven't so far found out anything different from whar I did. In a way, I wish I had. But I fear I'll have to dismantle my pen again and won't bet on my fixing pin's survival after another extraction.

 

From your earlier posting I got a sense that you had fitted the o ring and seal the wrong way around at the top of the piston rod (this could prevent the vacuum from clearing when the rod is pushed). Words can confuse so please take another look at the pictures and decide. .

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Thanks again northlodge. I am still sitting on a train and musing over your comments and invaluable drawings sent by praxim. According to the cutaway, I don't see any ring, either before or after the cup washer. Positioning this ring caused me some headaches. But I found out that it was needed to prevent the washer from sliding up the rod, past the built-in plunger lip, which apparently was not large enough to keep the cup washer in place. But if this ring was not originally foreseen, then it may cause the plunger to be in the wrong position. However, looking again at the cutaway, which position would in your opinion prevent the suction? I would think, if the cup washer would stop before reaching the point where the plunger chamber widens. But this would be the case, if I had misplaced the ring after the cup washer, considering that the plunger rests, in the closed position, firmly against the feed.

 

The other reasonable possibility is that the o-ring has moved, i.e. the packing was not tight enough to keep the o-ring in place. But the pen was popping all right when the rod was moving prior to fixing the knob.

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