Omas Parts - 556/s Piston Gasket

January 15, 2017

Hi, was hoping someone could help me find an Omas parts seller. Looking for a piston-gasket for an Omas 556/S. Please point me in the right direction. Thanks

January 16, 2017

Hi, was hoping someone could help me find an Omas parts seller. Looking for a piston-gasket for an Omas 556/S. Please point me in the right direction. Thanks

Very good question.

I've never been able to find omas gaskets and I did my own in Cork or adapting some o-rings.

January 16, 2017

Hi, I just fixed an Omas 556/S piston seal. My pen is from the 1950's. It is not hard to do, but you will need to tap out the little pin that holds on the piston knob. I used a thin sewing needle with the pointed end ground flat and just tapped out the metal pin - it comes out pretty easily. Then you can unscrew the knob and pull out the piston shaft.

These pens took a cork seal. The top of the piston shaft assembly has a little piece that screws on and off, which holds the cord seal in place. The cork on mine was all dried out and hard. First I tried to make a new seal, which I have done before, but I couldn't find any cork of high enough quality that wouldn't fall apart with the cutting and sanding. So I used the special O-rings that are sold by David Nishimura of vintagepens.com. By stacking two O-rings it takes the place of the cork and is much longer lasting and does not have to be kept wet, as cork does.

You can get a set of 40 O-ring seals from David Nishimura, 10 in each of four different sizes in envelopes marked A, B, C, D. The website says these are "Easily installed replacements for traditional cork seals, use singly or in pairs, or in combination with greased felt washers. Will fit a wide variety of vintage European piston-fillers...." I think I used the "A" size but it might have been the "B" size. You just have to experiment. lubricate with silicone grease.

These rings work very well and now the Omas 556/S works perfectly. By the way, I am sure there are other sources for these O-rings, but this is the one I know of.

Be careful when you try to take the pen apart and when you put it back together. Go slowly and gently because the old celluloid is very fragile. Gently heat the parts before you try to take anything apart or the celluloid might crack. By the way, putting back the pin in the piston knob is frustrating because you have to get the tiny holes lined up just right and it's hard to see what you are doing. It's not horribly difficult, but it took me many tries to line it up and actually get the pin to go in.

Good luck!

Richard

January 31, 2017

thanks for your posts. I ended up purchasing the o-ring seals from David and one of them did the trick for me. I was unsure at first because the only o-ring that would fit would, fit very snugly. However, after I put everything back together again it retains and handles the ink perfectly.

BTW - getting the pin back in was probably the most difficult part but once you figure out how it is supposed to work it's not too bad.

Thanks again!