Restoration Notes - Pistons On Vintage Kaweco Dia

[siamackz]

I recently bought a lot of three vintage Kaweco Dias. The piston on one of them wasn't working - I figured this was a good time to take my restoration knowledge and skills to the next level Here are my restoration notes in case they might be of benefit to anyone:

 

Step 1: Disassembly of piston - this is simple enough. You will notice that there is a threaded portion between the barell end and the blind cap. I used rubber grippers - left hand on barell portion to left of threaded portion, right hand on threaded part and turn counter clockwise. This should unscrew the piston and allow you to pull it out

 

Step 2: Examine the seal on the piston head - is it cork (with wax around it or not), rubber washer, o ring, etc! Mine had disintegrated cork with melted wax on it (that was wearing unevenly). The seal needed to be changed, clearly.

 

Step 3: Determine seal options - research showed that seals were typically made in cork for vintage pens. But, today many restorers encourage the use of rubber washers, or even better - O rings, as they are more durable and also much easier to instal (appropriate cork needs to be sourced, cut very precisely, smoothened, etc). Depending on what you have access to, and are interested in crafting, make your choice. I just could not find O rings that fit the pen at the hardware stores around my house. I stumbled upon a set of rubber washers that fit tight on the piston head, but they were way too large in outer diameter. This seemed like a problem I could work around, so I bought ten!

 

Step 4: Trimming the washer to make an appropriately fitting seal. This took hours of mistakes to figure out! First, I used a blade to cut and reduce the outer diameter of the washer. Once it got closer to the right size, I switched to sand paper filing and constantly checking to see if it is now fitting in the barell.

 

Step 5: Shove it in! Once the piston seal and head is small enough to just barely enter the bottom of the pen (without any resistance at all), that's when you know you are getting close. The barbell tapers as it goes closer to the nib, so if the head won't clear cleanly at the entry area from barbell bottom, then there's no chance it is small enough to work inside.

Once you can clear the bottom, don't push all the way up yet! Saturate the rubber washer with silicone grease. Now try pushing it into the barbell gently. You want light resistance, not too much. If it too much and you push it up, then you will probably lose the washer deep inside the barell as it gets stuck (pulling the piston out with force will simply dislodge the washer off the piston head). But, you can recover it with a pick, so no worries.

If the seal it too large, go back to sanding. Try pushing it up the barely again. And on and on... till the piston can move smooth but with resistance.

Be cautious about sanding too far - the seal will be too lose and won't suck up water. Take the pain to check often and sand little. It's the only way to do it. Yes, you will waste a lot of time and silicone grease (wiping off before sanding and regreasing to test each time).

 

Step 5: test for function - If it doesn't suck water, you went too far with sanding the seal, the diameter is too small now! Get a new washer and start over. If it sucks water, well done!

 

Step 6. Test for leaks - now ink I up with that ink that you have been regretting having bought! This is what it's for! It's tough to test for leaks with water. Fill with ink and leave over night. Check around the barbell threads and everywhere on the pen. No leaks? Great! Use it for a week, that's when you'll know if there is any leaking at all.

 

I was so happy with the first pen's restoration that I changed the seals on all 3 pens!

 

Here are some pics:

[Chrissy]

Excellent, thank you.

[Don Jr]

Siamackz,

I can't tell how soft/flexible your washer is, but piston seals need to have a little bit of "give" as well as "springiness"... I think Fountainbel calls this "radial tension" :^) This is one reason why cork works so well. My fear -without personally handling your example- is that yours may be too rigid, and therefore, risks breaking/cracking your barrel. Whenever possible, I try to refurbish my vintage piston fillers by using cork seals. Seal replacement is usually easy on vintage Kawecos, as the piston seal "seats" are held in either by pins or they screw into the end of the piston shaft. If you don't have access to the proper tools/materials to make your own cork seals, you can find sources for O-rings on line fairly easily. Here's a link to a set you can order from Amazon; 20 each of the smallest sizes in this set are the ones you'll find particularly useful, and even if you have to sand them down a bit once installed, it should be easier than the approach you just used:

https://www.amazon.com/CZORS-O-Ring-Assortment-Pneumatic-Hydraulic/dp/B0050JOJMQ/ref=sr_1_1?ie=UTF8&qid=1492037745&sr=8-1&keywords=O-rings+rubber

 

Hope this was helpful,

- Don Jr

[LizEF]

@siamackz, I hope you don't mind me asking, but this is the only thread I could find on disassembling these old Kaweco Dia pens.  I have an 805 EF.

 

 

It came to me from England (I'm in the western US), and was working fine at first, but now the piston is too loose and won't create a vacuum.  My suspicion is that the cork dried up (I'm in a desert and the humidity level here would be much less than in England).  I'd prefer to fix this myself, but I can't seem to find a way to unscrew the piston.  Can you please confirm where the threads for that are?  In the picture below, I'm guessing it's that jagged line / seam to the right of the "805 EF" and to the left of the threads for the blind cap.  If that's the case, can you confirm whether it unscrews counter-clockwise (normal) or clockwise (like TWSBIs)?

 

 

If that is where you're supposed to be able to unscrew the piston to do repairs, then I'll probably just send this off to someone because it won't budge in either direction (I'm afraid to try any more force than I have, and afraid to try anything at all to loosen the threads - not that I have a clue what I could try - it's not like penetrating oil would be a good idea).

 

Anywho, if you can confirm or correct my assumptions and let me know if there's anything I'm missing, I'd greatly appreciate it.  The pen wrote wonderfully, and I'd really like to use it again.    (I have more pictures, if that would help, but these seemed sufficient.)

[Nethermark]

You are totally right: the piston threads start at the jagged line. You need to use dry heat (hair dryer, etc.) on the back part of the pen, where the piston unit is in the barrel. Typically some kind of rosin or shellac was used to hold the unit in place and the barrel can have shrunk over time, so the unit is somewhat stuck. Now Siamakz tells it, as if this is a very easy repair. However, in some cases, it is very hard to remove the piston head from the piston unit. In that case, it would be easier to use O-rings than cork, as O-rings can be stretched over the piston head.

[LizEF]

6 hours ago, Nethermark said:

You are totally right: the piston threads start at the jagged line. You need to use dry heat (hair dryer, etc.) on the back part of the pen, where the piston unit is in the barrel. Typically some kind of rosin or shellac was used to hold the unit in place and the barrel can have shrunk over time, so the unit is somewhat stuck. Now Siamakz tells it, as if this is a very easy repair. However, in some cases, it is very hard to remove the piston head from the piston unit. In that case, it would be easier to use O-rings than cork, as O-rings can be stretched over the piston head.

Thank you, Nethermark!  That's very helpful.  Sounds like mine is well-glued (or I'm just too wimpy to apply enough force, or both).  I will ponder this, but it's making me lean toward sending it to a pro who will know what the resistance means, and how to overcome it without going too far.   I appreciate the quick reply.

[LizEF]

On 4/9/2017 at 1:44 AM, siamackz said:

counter clockwise

And I missed this when I was here last night!  So that's confirmed, too. Now to ponder.

[siamackz]

8 hours ago, LizEF said:

Thank you, Nethermark!  That's very helpful.  Sounds like mine is well-glued (or I'm just too wimpy to apply enough force, or both).  I will ponder this, but it's making me lean toward sending it to a pro who will know what the resistance means, and how to overcome it without going too far.   I appreciate the quick reply.

Nethermark is correct. See pic attached - the red arrow shows where you must grip (section pliers are very useful to grip this part securely, if not then atleast rubber grips for your hand), and the yellow highlight part is where you apply dry heat gently. Then with rubber grips in the other hand on the barrel you turn. 
 

The rubber holding both ends + heat are critical ingredients to ensure a safe disassembly because they reduce the need for unnecessary torque or other pressure applied to the body. 
 

you can use O rings for the seal or make a cork seal - here is how I do it with basic tools 

 

[LizEF]

57 minutes ago, siamackz said:

Nethermark is correct. See pic attached - the red arrow shows where you must grip (section pliers are very useful to grip this part securely, if not then atleast rubber grips for your hand), and the yellow highlight part is where you apply dry heat gently. Then with rubber grips in the other hand on the barrel you turn. 
 

The rubber holding both ends + heat are critical ingredients to ensure a safe disassembly because they reduce the need for unnecessary torque or other pressure applied to the body. 
 

you can use O rings for the seal or make a cork seal - here is how I do it with basic tools 

Thank you!  This is even better than I hoped.  I'll watch the video and do some pondering - DIY or send it off - getting and reworking the cork is my biggest concern - the person who gifted it to me warned me strongly against going the O-ring route.  Either way, having all this information puts me at ease and lets me make an educated decision.

[LizEF]

Just wanted to say thanks again to @siamackz and @Nethermark for the education.   After consideration and discussing this with a pro, I decided to send the pen off to said pro.  It'll be 3+ months before it returns (a good sign, IMO, when your pen repair person is that busy).  Hopefully it will work for a good long time once it gets new cork.

[katerchen]

I was going through the same pain just a couple of days ago, trying to fix an "Elite Meisterklasse" which as I came to understand is just a relabeled Kaweco.

 

I used a couple of square cuts of a bicycle inner tube for grip and applied a short burst of the hottest setting from a hair dryer.

 

The cork was in ruins and crumbled away almost immediately. I came across this listing by the one and only Mr Nishimura https://www.ebay.com/itm/141751477874 

 

I have a set on order, should get here on Friday. I'll post and see how far I get on my own 😛

 

-k

 

 

 

[LizEF]

28 minutes ago, katerchen said:

I was going through the same pain just a couple of days ago, trying to fix an "Elite Meisterklasse" which as I came to understand is just a relabeled Kaweco.

Interesting ebay listing.  Best wishes for a successful repair!   Looks like yours will get its medical attention while mine waits its turn...

[Nethermark]

8 hours ago, katerchen said:

"Elite Meisterklasse" which as I came to understand is just a relabeled Kaweco

An 'Elite Meisterklasse' is just one of Kaweco's many types of fountain pens, just as the 149 is a type of Montblanc pen and the Homo Sapiens is a type of Visconti pen. Actually, the Elite Meisterklasse would be one of their top pens, so congratulations on the great find!

[Adicus]

On 1/26/2022 at 4:57 PM, katerchen said:

I was going through the same pain just a couple of days ago, trying to fix an "Elite Meisterklasse" which as I came to understand is just a relabeled Kaweco.

 

I used a couple of square cuts of a bicycle inner tube for grip and applied a short burst of the hottest setting from a hair dryer.

 

The cork was in ruins and crumbled away almost immediately. I came across this listing by the one and only Mr Nishimura https://www.ebay.com/itm/141751477874 

 

I have a set on order, should get here on Friday. I'll post and see how far I get on my own 😛

 

-k

 

 

 

Thanks for this tip.  I was intrigued by these vintage Kaweco pens, but a bit worried about replacing a cork piston seal.  How did your replair go?  I am always on the look out for vintage flex fountain pens, did your nib have much flex?

[OCArt]

As an alternative the Majohn A1 is available in a lipless model.

[mizgeorge]

43 minutes ago, OCArt said:

As an alternative the Majohn A1 is available in a lipless model.

Think this might be in the wrong thread

[LizEF]

1 hour ago, mizgeorge said:

Think this might be in the wrong thread

Yes, but the image of a "lipless model" was worth it!

[RobHarding]

I have a few Kawecos from the war period and one Kaweco Dia 90 M, the pen is missing a clip but the body and nib are in great condition when dipped it writes beautifully. The issue arises with the piston screw  mechanism, it seems to have fused to the sleeve that should rise and fall. It is in its retracted position so I can't see the issue. My other similar Kawecos that have been taken apart seem to have an aluminium section of tube connecting the knurled knob on the end secured to the base of the piston mechanism, the thin aluminium sleeve seems to oxidize and break up easily (that pen is a helios 55), I assume the Dia 90 has a similar method of securing the knurled knob and I assume that is what has fused to the interior of the piston mechanism. Unfortunately I haven't been able to take this knurled knob off the Dia 90. the pin doesn't budge. I don't want to use too much force and break the piston mechanism. Can anyone give me advice on how to approach this problem and free up the piston?

[Nethermark]

Great pen! The 90 is the largest size of the Dia's. 

 

I also run into this problem from time to time with piston fillers. I can mostly solve it by either giving it a tour in the ultrasonic cleaner, or by heating it (dry heat from a hair dryer). But you have to be careful: it's probably made from hard rubber, which can discolour when it comes into contact with water and it can deform when heated too much.

[siamackz]

6 hours ago, RobHarding said:

I have a few Kawecos from the war period and one Kaweco Dia 90 M, the pen is missing a clip but the body and nib are in great condition when dipped it writes beautifully. The issue arises with the piston screw  mechanism, it seems to have fused to the sleeve that should rise and fall. It is in its retracted position so I can't see the issue. My other similar Kawecos that have been taken apart seem to have an aluminium section of tube connecting the knurled knob on the end secured to the base of the piston mechanism, the thin aluminium sleeve seems to oxidize and break up easily (that pen is a helios 55), I assume the Dia 90 has a similar method of securing the knurled knob and I assume that is what has fused to the interior of the piston mechanism. Unfortunately I haven't been able to take this knurled knob off the Dia 90. the pin doesn't budge. I don't want to use too much force and break the piston mechanism. Can anyone give me advice on how to approach this problem and free up the piston?

Nice pen. Everything looks fine to me from the pics so I cannot quite understand what the issue is. Also, you rarely need to disassemble further from the point you have on these pens, in my experience. Nevertheless, if your questions is about how to remove the pin from the knurled knob, in the past I have tried a few things (a) I don’t know what tools you are using but I use a thumb tac of the appropriate diameter and a small hammer - it’s important to ensure that the knurled part is on flat surface and well secured when doing this (b) if it’s stubborn, I spray wd40 while continuously trying to hammer it gently (from one side then the other), which allows the WD 40 to make its way inside too (c) if it’s still stillborn then I soak that part in WD 40 overnight and try hammer the next day (d) last resort I drill out the pin with a jewellers hand drill