Tibaldi Iride- Cracked Pump Housing

[fountainbel]

Hi all,

Just finished the repair of a beautiful Tibaldi Iride on which the thin walled pump housing was cracked.

After giving the matter some thoughts, I decided to make a new larger piston which fits directly in the larger barrel bore, and cut the original thin walled off from the filler housing ( already cut-off on the picture)

The only problem was that the piston screws on its stainless shaft with a 36 pitch thread, external diameter being only 3.8mm, and I did not have a tap.....

But after grinding a special thread cutting knife i was finally able the cut the thread on the lathe.

The new delrin piston seals directly using a standard with 0.15 mm radial pretension.

Reassembling and filling tests showed a perfectly working filler

This beautiful pen is again ready for a long lasting service !

Francis

 

BTW,After seeing the partly fretted thin outer wall of the pump housing - caused by enclosed ink remains between the barrel bore and the outer diameter of the pump housing- I was wondering why Tibaldi did not made the pumping piston directly in the barrel ( as I did now)

 

http://i62.photobucket.com/albums/h89/fountainbel/Repaired%20Vintage%20fountain%20pens/P1000427.jpg

 

[fountainbel]

Hi all,

Attached a clarifying sketch showing on top the original situation, and below how I've repaired the pen

Note i've forgot drawing the "breather tube" in the "repaired" situation, but logically its still there...

The piston shaft has a central bore allowing going over the one millimeter smaller breather tube.

Hope this clarifies the difference between the "original" and "after repair situation.

Francis

http://i62.photobucket.com/albums/h89/fountainbel/Repaired%20Vintage%20fountain%20pens/P1000430.jpg

[Flounder]

Thank you for this, very interesting stuff. What was the thinking behind the original piston cylinder sleeve? Stronger/smoother than the barrel material? Or perhaps the sleeve made it easier to meet manufacturing tolerances for a good seal?

[hari317]

Francis, is that a spring around the piston shaft in the first picture? what is its purpose?

[penboard.de]

Hi Francis,

 

compliments.

I had the same problem with two of them,

but went the other way, rebuild the insert from ebonite.

 

QUESTION and possible problem for your solution is the plastic you used:

Delrin is not fully resistant to acid.

And my Iride pens had suffered exactly from that - especially transparent celluloids tend to decompose and while slowly doing that - they evaporate nitric acid.

 

so I replaced all the internals with ebonite.

 

Best regards

Tom

 

 

 

[penboard.de]

BTW

had a closer look at your solution,

 

could you show a picture of the repaired pen, A close up of the barrel end?

 

your solution - basically the same - reviving the vac-fill system,

first got it wrong - thought you made the pen become a pistonfiller... :-)

 

while my solution maintains the original at 100% (sum people will prefer that)

your solution shows a bit more of the inside, especially the piston at work inside the semi transparent barrel. (sum others will prefer THAT)

 

just do it from ebonite... otherwise you will need to redo the work in some years time.

 

Next Iride that arrives I will copy your solution. :-)

 

Saluti

Tom

[hari317]

your solution - basically the same - reviving the vac-fill system,

first got it wrong - thought you made the pen become a pistonfiller... :-)

 

Ah, Vac filler, I was under the same confusion, now it is clear. thanks Tom.

[fountainbel]

BTW

had a closer look at your solution,

 

could you show a picture of the repaired pen, A close up of the barrel end?

 

your solution - basically the same - reviving the vac-fill system,

first got it wrong - thought you made the pen become a pistonfiller... :-)

 

while my solution maintains the original at 100% (sum people will prefer that)

your solution shows a bit more of the inside, especially the piston at work inside the semi transparent barrel. (sum others will prefer THAT)

 

just do it from ebonite... otherwise you will need to redo the work in some years time.

 

Next Iride that arrives I will copy your solution. :-)

 

Saluti

Tom

 

Hi Tom,

The pen is already shipped back to the owner in the meantime...

Agreed, Ink containing a high percentage of acid could attack the delrin.

However, given given a solution with 20% acid the resistance is specified as being "fair", i'm not really affraid the delrin will be deteriorate.

Note also the delrin piston is not in contact with the barrel wall, being 0.5mm smaller in diameter as barrel bore.

Thanks for tor advice though, i'll surely keep it in mind and also use HR in the future !

Drawback of the original piston housing is the fact that ink remains penetrate between the long radial seam between the original piston housing and the barrel bore.

These ink remains can't be removed by flushing the pen, so when changing inks there will always be a risk de new ink is contaminated with these old ink remains.

In fact the owner- who loves changing inks - suffered from this ink contamination problem long before the filler became defective

Using my repair approach these contamination risks are completely eliminated

 

Cheers, Francis

[penboard.de]

Hi Francis,

 

ink hiding in the original design of the mechanism,

thats a good extra motivation for the modification.

BUT keep in mind, I did not think of the acid ink,

i referred to acid emanating from the celluloid.

 

I am sitting on a batch of no nib Iride pens,

took them out of the drawer to check, and to learn, how they were made.

and found the black inserts already decomposing.

Just because of the celluloid.

 

check these posts on FPN about celluloid pens cristallizing.

that mostly starts at the transparent parts of the pen,

missing (mostly basic) pigments accelerate the process in transparent celluloid.

(took this wisdom from a book on celluloid from 1934)

 

Best regards

Tom

[newlife]

A very interesting pen, thanks for giving us insight!

 

Klaus

[rogerb]

Eeek ... this is scaring me!

I have lovely Iride set with a sweet Broad nib .... I have never figured-out the 'vac' filling system, which has a REALLY strong spring, so I just unscrew the nib and fill it with a syringe Huge ink capacity that way, so no problem doing it.

 

Sounds as if I'd better ink it up with gentle ink and enjoy it while it lasts!!!

(I have a FPN friend who covets it dearly!)