Vintage Mb Telescopic Pistons

[fountainbel]

Hi all,

 

The MB telescopic filling system really is a mechanical juwel , which – being a mechanical engineer- I'm very found off

 

Given the confusion there is on the need to back-up the piston against the section edge for efficient filling, attached my sketch showing the working principle of the MB telescopic pistons.

 

The sketch shows the system of a pen in the vintage 14X range, although the principle is similar for the 13X range and in fact for all MB telescopic fillers.

 

And yes, one really has to turn the piston down till its backs-up against the section edge, otherwise the piston will not make its complete telescopic stroke.

 

A pen on which the piston has not to back-up against the section end, yet allowing the full piston stroke is - in my opinion - a pen on which the piston cork tension is"on the edge", meaning the cork will probably leak.

 

Contrary to normal piston fillers, obtaining the optimum radial pretension of the cork is very delicate.

 

In my experience a radial pretension ( on diameter ) of 0.10/0.15mm is the optimum

 

Surely when the barrel bore is slightly wider at the section side - which is sometimes the case - one has to fiddle and optimize de cork diameter to get a good result.

 

The friction of the cork in the barrel should be as low as possible , while fully tight.

 

I therefore soak the corks in a liquid paraffin /beeswax solution for one hour , heated up"au bain Marie".

 

Doing so the solution penetrates in the cork cavities, resulting in reduced friction inthe barrel and reducing the back-up force piston/section end needed to avoid slipping of the blind cap thread fit.

 

Hope this clarifies somewhat the working principle of these beautiful - real Meisterstuck- pens.

 

Francis

http://i62.photobucket.com/albums/h89/fountainbel/Repair%20suggestions%20to%20forum/MBtelescopic002Kopie.jpg

Edited January 7, 2012 by fountainbel

[hari317]

Dear Francis, unable able to see the sketch now. Much appreciated.

 

Thanks!

Hari

Edited January 7, 2012 by hari317

[pavoni]

Wow, how lucky we are to have you contribute to this forum Francis.

 

Thank you very much for the excellent (and typical) Fountainbel explanation.

 

Pavoni.

[specialk0449]

Francis thank you for your detailed drawing and explanation of telescopic pistons.

[Wael El-Dasher]

Fantastic section Francis. Please don't tell me you drew it on a drafting table

 

cheers

 

Wael

[yus2001fr]

Hello, Francis

 

It's really nice to see this beautiful mechanism ... I appreciate this in my 3 Celluloid Montblanc Meisterstück from the 50ies, 142,144 and your 149 !

 

Regards

Yves

[fountainbel]

Fantastic section Francis. Please don't tell me you drew it on a drafting table

 

cheers

 

Wael

 

In fact I've drawn/sketched it on our living table, took me just 2 hours.

 

Francis

Edited January 7, 2012 by fountainbel

[Soot]

Francis, you're a treasure to the board!

 

Always drawing up excellent schematic sketches of pens that we love and treasure, helping us understand the inner workings of the mechanism. We can't thank you enough! A big thank you!

 

 

Bob

[georges zaslavsky]

outstanding piece of engineering

[orfew]

That is very very helpful. I was wondering how the telescoping mechanism in my 142 actually worked. Thanks very much for the excellent schematic.

[FredRydr]

Very cool! Thank you, Francis. Now I can build millions of them.

 

Fred

[apatel]

Wow! I wonder why they abandoned such a great filling mechanism? :hmm1:

[fountainbel]

Thanks for your comments !

Major reason why MB went away from this excellent filling system is its complexity, hence the cost.

Secondary reason might be blotting risks due to the large ink tank volume.

Specially when the ink volume is low, the risks for blotting by air expansion triggered by temperature and air presuure fluctuations.

is higher

Francis

Edited January 10, 2012 by fountainbel

[hari317]

Francis, can this filler be reproduced in delrin? as a drop in replacement for current MB piston pens, but with greater stroke?

[fountainbel]

Francis, can this filler be reproduced in delrin? as a drop in replacement for current MB piston pens, but with greater stroke?

 

Not in my opinon

One can't obtain the ridgidity in delrin

The design is perfect as is..........

Francis

Edited January 10, 2012 by fountainbel

[Maxpens]

Francis, can this filler be reproduced in delrin? as a drop in replacement for current MB piston pens, but with greater stroke?

 

Not in my opinon

One can't obtain the ridgidity in delrin

The design is perfect as is..........

Francis

 

 

since 1936 !

 

D.R.P. 746437 Patentiert im Deutschen Reich 23. Februar 1936

 

http://www.maxpens.de/bilder/mbpate6.gif

 

kind regards

 

Max

[FredRydr]

since 1936

Thanks for that, Max! Now, to have it matted and framed.

 

Fred

[Readymade]

I wonder if the need to push the piston down till it backs up against the section edge contributed to my pen breaking? I love the telescopic mechanism for its weight and materials, but might it place too much stress on the celluloid? :/

 

[draeroheli]

Great engineering work. Francis, Good to see you again on this Forum.

 

 

[Mikale]

When I read Barry's article on the 149 he briefly mentioned this telescopic filling system and I wanted to know more about it. Thank you for such an educational thread