Big Ben Piston Trouble

[Ernst Bitterman]

I have before me a Big Ben, which is apparently a Danish brand. It's a piston-filler, and there's clearly something amiss with the mechanism; turn how you like, in either direction (and it seems that the pistons in these things turn the opposite way to the usual arrangement), and there's no sign of the piston travelling in the chamber. This means I should open it up and see what's what.

 

...and there I stop. This is not a familiar mechanism to me, and from what I can discover, it's not a familiar brand period. Looking into the second edition of Marshall and Oldfield, I find nothing exactly on point. The closest I find to the exterior appearance is the Conklin Nozac of the previous generation, but being a cautious sort, I'd like to see if anyone here has any tips on proceeding. Driving out the pin in the knob seems the right first step... but sometimes that first step is the one that detonates a mine.

 

The subject (despite appearances, the lower part of the barrel IS an ink window):

http://ravensmarch.files.wordpress.com/2012/11/dscn2675.jpg

 

The (suspected) incision site:

http://ravensmarch.files.wordpress.com/2012/11/dscn2678.jpg

[newlife]

Hello!

 

This is definitely a piston filler! And there's no need driving that pin out. Simply grab the visible part of the thread between filling knob and barrel with a soft tool like a section plier and turn counterclockwise. A little heat or watering before surely won't do any harm. In some cases those threads have been secured with shellac, mostly not. Patience please!

 

It might happen that you can turn out only part of the piston and the spiral inside holding the cork rests inside because it's "glued" inside with old ink. In this case more watering will help, ultrasonic too, if the nib is NOT goldplated; massive gold will not suffer.

 

You'll have to recork that pen for sure, I believe.

 

Was this helpful?

 

Cheers, Klaus

[Ernst Bitterman]

Very helpful, although I've not had a chance to apply it. Just a quick comprehension check; if the threads were compatible (IF!), I could use a Vacumatic wrench to extract the mechanism... right?

 

Heat and patience, definitely, with patience being the most important tool in the kit.

[newlife]

Yeah, something like a vacumatic tool. You might try a wooden clothespin too or something like that. I also use a tool made by myself, similar to a nutcracker, works very well and does no harm to threads.

 

Good luck!

 

Klaus

[Ernst Bitterman]

Application has occurred, and despite the near-fatal pressure a cold is inducing in my sinuses, I want to share for the public good:

http://ravensmarch.files.wordpress.com/2012/12/dscn2687.jpg

The majority of the mechanism housing is a mere tube, inside which the element moved by the knob hides. There is a threaded hole at the end of that element, into which the piston itself fits. There are two seal components, one annular and the other more of a cap. That seal arrangement is odd, but it's not the BIG oddity: the piston will just turn freely with the knob if left to its own devices. The only way it moves is through the resistance offered by the seals, so unlike the familiar mechanisms in Lamy, Pelikan, TWSBI, Osmiroid and Dollar pens, the seals twist as they go in addition to the fore-aft motion. I don't know if this is going to help or hurt in seal life.

 

Fabricating new seals is going to be some fun, too.

[fountainbel]

I could be wrong, but as far as I can see there is only one (cork) seal and a seal enclosure nut?.

The piston set-up without an anti-rotation guidance is not really exceptional..

Even some Luxor fountain pens are working as such.

I would suggest to install two O rings on the cork seat, having 0.1-0.3 mm radial pretension on the cork seat and 0.1-0.2 mm pretend-sion in the barrel

In the ridge between the O rings you could apply some silicone-grease.

I'm sure you can find some fitting Orings for this placation.

If you specify the exact cork seat and inside barrel diameter, I will let you know which O ring should do the job.

Francis

 

 

[newlife]

Hi Francis!

 

I'm not really into o-rings cause I don't know how to measure them. For me cork is the number one, because I can make them all by myself. Well, I know there are some manufacturers here in Europe who supply o-rings like you use, but that's totally difficult I believe if you're not experienced. I have reasons to believe that you might have made a list for yourself to make it easier on yourself if it comes to standard jobs like fixing standard pens. Should you have made up some kind of list like that, please give us some clues! You know, I often experience varying diameters with pens. I have an MB 234 1/2 for example, one of that kind that requires cork replacement from the front after removing the section, you surely know that model. Now I notice after making a new cork - not a big deal - that the barrels's inner diameter varies. It is conical, its diameter increases when the piston is drawn up to fill.

 

Well, I now have bought a tool to measure the inner barrel diameter to prevent such mistakes like making a cork disregarding conical barrels, hope it will help me. But if you should have some kind of list showing your experiences that might be very helpful to all of us!

 

Greetings to all of you, thanks to this forum, where all of you experienced masters of pens supply us normal folks with your knowledge!!! I'm from Germany, there's one forum with some very experienced - private - guys sharing their knowledge - penexchange.de - but don't you believe that any of those german pen masters shares his knowledge with the community over there!!! That's why I'm glad to be here sharing my knowledge, being sure I get something backk too if I'm in need. Great! I'd better not get too upset about my fellow german repairers though . . . but it's kind of frustrating . . .

 

Regards, Klaus

[Ernst Bitterman]

Francis-- I was quite surprised to NOT find cork in this pen. Both the annular object and the end-cap are rubber. I do take what you say on-board, and the prospect of o-rings does clear up some of the trepidation I've been feeling. For some reason, if they're not in there ab initio I tend to forget them as a possibility. I'll get a battery for my calipers and post some diameters as soon as I can.

 

Klaus-- Troubling news of insularity in Germany! I'm glad you're willing to share, as it was the section pliers you suggested that did the job for me.

[newlife]

Hello Ernst!

 

Should you be interested what my selfmade tool looks like, well here's a photo.

 

http://imageshack.us/a/img818/1576/img0067ede.jpg

 

It's made of beechwood and is good enough for what it's supposed to be. Francis might laugh seeing it, he makes far better tools I know, he's a damned good engineer, you know!? I'm not that good with metal work and never will be, so I have to make the best of what's inside me. Not bad either, I think!

 

Cheers, Klaus

 

P.S. The steel nail may serve for opening certain mechanisms like MB or UHU-pens, both from Germany. The photo doesn't show it, but you can push it through the wooden strip to engage those holes in the piston mechanism.

[whych]

@newlife

Great idea that. Being wood, you don't have the problem that you are going to damage the pen plastic.

What thickness wood did you use for the handles?

[newlife]

Hi whych!

 

My tool is made out of 4 mm beech wood and serves me quite well. Of course there's some signs of wear after some time, but after all it's not expensive to remake it. Improvement could be done by applying thin rubber layers where the drillings are made for gripping, but I don't know what kind of glue would be best. Rubber and wood don't match very well. But as it is you really don't get any scratches by using without rubber.

 

I even believe you could use this on vintage MB's pistons with wooden bars stronger and thinner than beech, just because the filler knob doesn't leave much space for a 4 mm beech tool. Ebony might do the job if you can get it, just ask your carpenter which kind of wood might serve well.

 

Hey, I'm glad for your feedback, that's what we're here for, helping each other and of course for some backslapping too!

 

Klaus

[crazypencollector]

Ya,that is very nice tool.Smart!

[whych]

Improvement could be done by applying thin rubber layers where the drillings are made for gripping, but I don't know what kind of glue would be best. Rubber and wood don't match very well. But as it is you really don't get any scratches by using without rubber.

It did cross my mind that you could add a bit of rubber or something to the holes. Why not try some 4 or 5 mm thin wall plastic/polythene tube. Cut it longitudinally down its length and push it into the wood.

That way, if you don't need it, you can pull it off.

To make the wood thinner around the holes so it will fit into the space between a piston knob and the body like with MB, Geha, etc. use a router and rout a bit off the sides. If you use a straight flat bottom router bit with a diameter of 1 or 2 mm bigger than the hole diameter, it should be fine.

You are pushing the handles together so the wood shouldn't break.

Perhaps, if there are more replies to the tool, we need to start a new thread.

Edited February 26, 2013 by whych