Help Required! How Do You Operate A Telescopic Piston?

[Pennenut]

Hello,

I am wondering how do you operate a telescopic piston filling mechanism? Can someone detail the steps involved?

Thank you for your help!

 

Pennenut

[hari317]

To the user, it presents just like any other Piston filler.

 

Unscrew the knob till it can no longer be moved. Dont use too much force.

 

Dip the nib in ink such that the entire nib including lip of section is submerged in ink.

 

Screw the knob back in fully.

 

Wipe the nib feed and section with a soft cotton rag.

 

Use your pen.

[zaddick]

So that is true Hari, but the difference is that there are two very different resistance levels for each stage. The first stage can feel like the piston cone is almost free spinning and the change between stages can almost feel like you broke something if you are unfamiliar with the sensation. But rest assured, it is likely working just fine. Once you get into stage two there will be more resistance and you need to go until the cork or piston head firmly hits the bottom of the chamber or the mechanism will not retract properly.

[siamackz]

Another important thing to remember is that once extended if you want to pull the piston back in to fill ink then you must first ensure that the filler was completely extended otherwise it will not pull back it. Some resistance must be felt against the feed/section after extending before you can pull back in. You can read about it somewhere Im sure.

[fountainbel]

Hi Pennenut,

FYI, attached a section drawing of the 13X telescopic filler.

The 14X telescopic system is slightly different , but functionally identical.

As rightfully explained above by fellow member Zaddck, entering the second retraction stage one feels an increased restriction.

This is however normal , the primary small diameter lead screw features a lead pitch of 4.5 mm, while the larger diameter secondary lead screw feature a lead pitch of 6.0 mm.

When retracting the piston the smaller lead screw will screw in first, since its actuating torque is lower due to the smaller lead pitch.

Once the primary small lead screw has finished its stroke, the secondary large lead screw will start the second stage retracting movement .

At this moment one can feel a higher restriction, needing a slightly higher actuating torque, triggered by the larger lead screw pitch.

As already mentioned above by fellow members , backing up the piston against the section when moving the piston down is needed to "re-arm" the slipping clutch which is inside the filling knob.

Other wise the clutch may slip after the first retraction stage, hence the piston will not retract completely .

An ingenious system, I like it very much ….

Best regards,

Francis

 

http://i62.photobucket.com/albums/h89/fountainbel/Repair%20suggestions%20to%20forum/P1010028.jpg

[zaddick]

Leave it to the engineering master to provide the most thorough, technical, and complete answer! Thank you Francis for your always helpful illustrations.

[siamackz]

Leave it to the engineering master to provide the most thorough, technical, and complete answer! Thank you Francis for your always helpful illustrations.

+1

[Seney724]

I'm hoping for some clarification about the normal, expected, operation of Montblanc's telescopic filling system.  I have two 50's Montblanc celluloid Meisterstuck fountain pens (a 149 & a 146) each of which have the telescopic (2 stage) filling  system.  Both work fine, but they are very different in the way they fill the barrel with ink.

 

Both pens are the same when the piston is deployed.  The turning knob seems to spin freely for a few turns (1st stage deployment) after which a definite sense of engagement of the piston is felt (initiation of the 2nd stage of piston deployment)  Following this, the piston descends and, as per the recommendations of @fountainbel & others in several threads here, I have the piston fully descend until it comes in contact with the top of the section.  This is all fine, and as I understand it, reflective of a totally normal operation.

 

It is when I go in the opposite direction, the retraction of the piston back up into the barrel for which I am unclear as to what is the expected normal finding.

 

On the 149, when I begin the process it is a simple reversal of what occurred when the piston was deployed.  The first thing which occurs is the retraction of the piston head and, after it retracts well up into the barrel, the turning knob spins much more freely which is, I think, the retraction of the 1st stage all the way back up into the barrel and the return to the correct starting position.

 

For the 146, when I begin the process (again, the piston head is at the top of the section) the turning knob turns with some resistance but nothing happens.  After I turn it several turns, the piston finally begins to retract up into the barrel.  The sense I am getting is that the 1st stage is retracting before the 2nd stage.  But, at the end, the piston head is far enough up into the barrel that it cannot be seen through the ink window.

 

So, which of my pen is exhibiting the expected, "normal" operation of the telescopic filling system, the 149 or the 146?   And, for the one which is not functioning normally, is there any cause for concern or a need to get it looked at by an expert??  Given that they both fill with more than enough ink, I am not anxious to have the one which is not working normally disassembled.

 

Thanks!

[omarcenaro]

Just inserting the diagram that Fountainbel linked in 2019 so it’s visible to all.

[Seney724]

1 hour ago, omarcenaro said:

Just inserting the diagram that Fountainbel linked in 2019 so it’s visible to all.

Thank you.  Yes, a really terrific diagram and a most valued reference source.

I have read every word again and again.

But, unfortunately, unless I am missing something, it does not provide the answers or any insights into the question I have posed.

[stoen]

On 3/25/2023 at 4:10 PM, Seney724 said:

The turning knob seems to spin freely for a few turns (1st stage deployment)

Not so. The turning knob first makes a few free spins, extending from the “locked” position, before the deployment mechanism (1st stage) gets engaged, AFAIK. 

 

Hope this can help.

🙂

 

 

[Seney724]

3 minutes ago, stoen said:

Not so. The turning knob first makes a few free spins, extending from the “locked” position, before the deployment mechanism (1st stage) gets engaged, AFAIK. 

 

Hope this can help.

🙂

 

 

Thanks for your input.

Apologies if I was not clear enough.  I'm not so much concerned about the descent of the piston as I am its retraction back up into the barrel. 

Do you have any thoughts about that?

[stoen]

1 hour ago, Seney724 said:

I'm not so much concerned about the descent of the piston as I am its retraction back up into the barrel. 

I know that it has to extend all the way until touching the section from inside. Gently, but firmly. Else it won’t retract fully.

 

[Seney724]

3 minutes ago, stoen said:

I know that it has to extend all the way until touching the section from inside. Gently, but firmly. Else it won’t retract fully.

 

Yes, this is true.

But, it is not the question I have posed.

Thanks for trying to help, I appreciate your time.

[stoen]

1 hour ago, Seney724 said:

But, it is not the question I have posed.

Your particular question implies one of your pens may be broken in terms of inking action. The information you’ve provided is not enough for me to give a decisive and precise aswer. Without being able to come to precise conclusion, I opted for giving a more general answer: the retraction should normally mirror the deployment.

 

Therefore, whenever piston retracted, the knob starts turning more freely. Often I feel no physical difference between 1st and 2nd stage retracting.

I have a spare telescopic mechanism here. The piston friction also affects the mechanism behaviour, AFAIK.

 

The knob “unscrewing” and screwing back take approx. 4 U-turns each.

 

The mechanism deployment and retraction take approx. 8 U-turns each.

 

One way for you to get more data could be:

- getting information on exact ink capacities for 149 and 146.

 

- measuring the intake of your particular pens.

 

Hope this can help.

[fountainbel]

1 hour ago, stoen said:

I know that it has to extend all the way until touching the section from inside. Gently, but firmly. Else it won’t retract fully.

 

Exactly!!

The piston should not only "touch" axially the section, but effectively "back up" against the section, applying a relatively firm axial pretension.

Doing so the slipping clutch ring inside the filling knob gets enough axial pretension inside its housing to ensure a full retraction stroke.

Wishing you success !

Francis

[Seney724]

4 hours ago, fountainbel said:

Exactly!!

The piston should not only "touch" axially the section, but effectively "back up" against the section, applying a relatively firm axial pretension.

Doing so the slipping clutch ring inside the filling knob gets enough axial pretension inside its housing to ensure a full retraction stroke.

Wishing you success !

Francis

Many thanks Francis.  Your input & insights are very gratefully appreciated.