Omas Piston Filler Repair, Sheared Anti Rotation Key

[fountainbel]

Hi all,

Just repaired a small size Omas piston filler in titanium on which the filler was defective.

The inner barrel part is however plastic, only the outer sleeve is made from titanium

The filling system was still complete, however the anti rotation key inside the barrel was worn off / sheared off.

So the piston rotated together with the filling system and did not move axially when rotating the filling knob.

The filling knob -which is to be glued permanently on the filler housing - was loose, most probably by applying excessive torque with a blocked piston.

After measuring an sketching the inner bore of the barrel I realized he only thing I could do was turning the piston bore out - removing the largest part of the smaller diameter worn anti rotation part - and install a friction fitted replacement ring featuring an anti-rotation key.

Enlarging the diameter deep in the barrel was a delicate operation since I wanted a 0.05mm radial pretension between the ring and bore fit.

Shearing/ wear of the anti rotation key seems to be a real weakness in these beautiful Omas pens......

i've already done a few similar repairs, so I had made me already a reaming broach which allows me - starting from a ring with a smaller diameter - to enlarge the bore while making guiding key by pressing the broach through.

This worked out fine, the piston works perfectly now and the filling knob is glued on the filler housing.

And most important, the owner is very happy his beautiful pen is functional again !

Francis

http://i62.photobucket.com/albums/h89/fountainbel/Repaired%20Vintage%20fountain%20pens/P1010130%202.jpg

http://i62.photobucket.com/albums/h89/fountainbel/Repaired%20Vintage%20fountain%20pens/P1010131%202.jpg

[Dr.Grace]

Bravo Francis, it's so good to see that you can fix these delicate pens!

[Chrissy]

Good job Francis. I will certainly bear you in mind if I ever have a problem with one.

[eckiethump]

Hi Francis,

I have the same pen, but plan on making it a vacuum fill type of piston filler, well that's the plan anyway ? My own pen so no particular rush, but too nice to just have lying around as parts.

Eric

Edited January 25, 2017 by eckiethump

[luigilevin]

thanks Francis for your excellent advice and drawings

[ChristianEl]

I know I'm very late to the party, but I have an Omas Buffetti that has that exact problem, except, I think the anti rotation key was part of the barrel or glued in as the whole barrel is just plastic.

 

 

Francis, would you mind sharing your photos again? Thank you so much!

 

Christian