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ED conversion using teflon tape


Titivillus

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OK now that I have a Kaweco Sport another thread has made me start thinking about ED conversion to it. There is no brass plug and the only metal is in the cap. I am curious about using plummers teflon taper rather than any liquid sealant. As I have a roll of the tape and nothing else.

 

Anyone else use teflon and had success/ leaking failure??

 

 

Kurt H

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Teflon tape can work but you have to ensure that you only use one layer as multiple layers can add undue stress at the section / barrel joint and cause fractures. Even with one layer there could be an increased risk of fractures so please assume that this risk is present.

 

I would always opt for silicone grease, vac sealant, or plumber's wax instead.

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Teflon tape can work but you have to ensure that you only use one layer as multiple layers can add undue stress at the section / barrel joint and cause fractures. Even with one layer there could be an increased risk of fractures so please assume that this risk is present.

 

I would always opt for silicone grease, vac sealant, or plumber's wax instead.

Good point. I've done alot of glassware with teflon connections and was curious why more mention of the tape was not around.

 

Krut H

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Hi Kurt,

 

I would agree with Keith on this point, speaking from personal experience :D. I tried to repair a BHR ED when I didn't know anything about pen repair, and didn't have any tools, and so I tried teflon tape, which I use a lot around the house to stop liquid things from bleeding out of pipes and tubes :D.

 

Just 2 layers, and "crack" said the barrel. Blue black fingers was the result. Since then I found a few pen boards, and silicon grease, and that is what I use nowadays :D.

 

HTH, warm regards, Wim

the Mad Dutchman
laugh a little, love a little, live a lot; laugh a lot, love a lot, live forever

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OK now that I have a Kaweco Sport another thread has made me start thinking about ED conversion to it. There is no brass plug and the only metal is in the cap.

 

You must have one of the "Ice" ones. Mine are the metallic and there is a plug in the very end of the barrel. I used Giovanni's section sealant for the ED conversion - worked great (no affiliation, just a happy repeat customer . . .)!

 

Let us know how it turns out.

"But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us." (Rom. 5:8, NKJV)
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Hi Kurt,

 

I would agree with Keith on this point, speaking from personal experience :D. I tried to repair a BHR ED when I didn't know anything about pen repair, and didn't have any tools, and so I tried teflon tape, which I use a lot around the house to stop liquid things from bleeding out of pipes and tubes :D.

 

Just 2 layers, and "crack" said the barrel. Blue black fingers was the result. Since then I found a few pen boards, and silicon grease, and that is what I use nowadays :D.

 

HTH, warm regards, Wim

Yes I've had some experience where I needed to use an exacto knife to cut a length to minimize overlap. It seemed to work there and was curious as to history from others.

 

 

K H

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Kurt and others,

 

I understand the concern of repairers who are advicating passionately against Teflon, but I think they are overdoing it. Of course if one has to chose between teflon and sealants (like silicone grease) there is not doubt that silicone grease is more preferable.

 

Because many times we want to "fix" things immediately and chances are that there is a teflon tape around but not always sealants, I have the following recommendation.

All it takes to see whether 1 layer of Teflon is OK, is to test the backlash of the connection. Unscrew partially the threaded connection and see how much play there is. If there is some play then a layer of teflon is OK.

 

In a threaded connection, there is always a clearance as shown in the following picture. I have played a lot with teflon in threaded feeds that leak but my comments are true for any threaded connection. For example, the backlash for the Estie nib to be about 250 microns (10 mils) in both directions (a and b in the Figure below) while for the Sonnet and the Pelikan about 150 microns (6 mils;). The backlash in Optimas actually feel smaller - I can not estimate it well - if I had to guess I would say that it looks as small as 40-60 microns (2 mils). Leaking is typical in feeds that had the theads close to the bottom of the section (such as Esties and Sonnets), while the design of Pelikans or even better Optimas is advantegeous since it has the threads deaper in the section and minimize any risk of leaking.

 

http://mywebpages.comcast.net/azavalia/TEFLON/1.jpg

 

What makes a feed leak is shown in the next figure. When the feed is tighten then one side of the feed meets the corresponding side of the thread on the section. This does not happen for every flight of the thread. The remaining gap is smaller than the backlash but large enough for the ink to leak.

 

http://mywebpages.comcast.net/azavalia/TEFLON/2.jpg

 

How teflon works on a threaded feed/section is shown in the following picture.

Unless you apply multiple layers, a single layer of teflon does not jam completely

the gap between the two sides. The reason is that the local thinkess of the teflon is as small as 20-40 microns (1 to 2 mils). This is much smaller than the backlash (5-10 times).

 

http://mywebpages.comcast.net/azavalia/TEFLON/3.jpg

 

The thickness of the teflon tape (if you do not stretch it) is about 75 microns (3 mils). If you stretch is it becomes much smaller :) The common telfon tape (in contrast with the high density teflon tape) is very porous. The density of teflon tape is as low as 0.3-0.4 g/cc while the density of PTFE is 2.6 g/cc (PTEF is the solid which Teflon tape is made from). The picture below is from a scanning electron microscope. The pores are of the order of 0.5 microns - which means it is liquid impermeable since the capillary forces are immense at those dimensions. When you apply a layer of teflon and you tighten you pretty much close most of the pores locally. This descreases the local thickness of the layer to about 1 mil; or less which is much much smaller than the typical clearance.

 

http://www.uiowa.edu/~image/images/microscopy/EM2/teflon_sem.jpeg

 

So if there is enough play in a threaded connection and unless you wrap multiple layers, there is no problem with using teflon tape :)

Fine print: DO NOT BLAME ME IF YOU BREAK YOUR PEN USING TEFLON :o

Edited by antoniosz
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Hi Antonios,

 

Wow! Thanks for the thorough explanation and accompanying pics! Great piece of work (again :D)! And very useful, of course.

 

Maybe we need to create a standard pinned hread here on the board, with all of these extremely thorough, insightful and useful messages copied into it. I don't know whether that is possible, but worth investigating I think :D.

 

Warm regards, Wim

the Mad Dutchman
laugh a little, love a little, live a lot; laugh a lot, love a lot, live forever

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AZ - very nice work. Thanks for the effort and for sharing!

"But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us." (Rom. 5:8, NKJV)
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