# Anyone had thread failures with PR?



## Dan_F (Dec 29, 2009)

Has anyone either had problems tapping PR, or had thread failures after using a tapped PR blank for a while? Just wondering if these will be as durable as the acrylic ones. Thanks,

Dan


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## cnirenberg (Dec 29, 2009)

Dan,
I had some problems with the threads in a multi colored PR cast blank.  I don't know think it was the PR itself but possibly the powders that made up the deep colors (i.e silver, bronze etc.)  It was a 10x1 thread (used a die with the standard lubricant etc.)and the threads chipped so bad I had to scrap and move on.  The tenon looked good and was as true as I could get it with a wood lathe. I haven't been able to try more PR to see if it was me or the material.  I will try next with a metal lathe to see.  Hope this helps in some way.


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## bgray (Dec 29, 2009)

Most polyesters thread very poorly.

I avoid them.  If you are going to try it, use lots of lubrication/coolant, and very very light cuts.  You will need to single-point them, I wouldn't try a tap.

But even then, I don't like trying.  The threads might function, but they will most likely chip and not look attractive, at best.  

There are so many standard acrylics to choose from, that I find no reason to use PR's, if they need to be threaded.


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## BRobbins629 (Dec 29, 2009)

I have to agree with Brian, but if you really like the PR or it is a special cast, you can bore out the end and make an insert from something that threads easily.  I usually use ebonite and glue it in with epoxy.  Saves a lot of anxiety over cracking a special blank.  I've even done this with wood blanks.


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## cnirenberg (Dec 29, 2009)

Thanks for the heads up on this.


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## Dan_F (Dec 29, 2009)

Thanks.  I'm trying to find a way to use some of Dawn's lovely casts for kitless fountain pens. This is my first experience with PR, and just from turning them round, it didn't seem that they would take to tapping. Oh well, back to the drawing board. 

Dan


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## skiprat (Dec 29, 2009)

Dan, I tap Dawns PR on a regular basis and I find that if you can incorporate some sort of re-inforcement like a cb then it works fine.
Here is one I did some time ago.


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## apple320 (Dec 29, 2009)

*And I though it was only me*

After fighting with this problem this was the way I was able to deal with it






Chris


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## Dan_F (Dec 29, 2009)

Skiprat---I have been tapping a black acrylic center band for my pens, but then that still leaves the male threads of the barrel to go into the center band, as well as the females in the barrel to hold the section. In addition, I also thread the cap finial so that I can turn it and the cap at the same time for a perfect fit, and then unscrew it to install the clip. I would worry about the longevity of the threads, even if I were able to create them. 

Apple--- That's the way I was thinking of going, only having the black portion of the barrel set into the PR so that the minimum - just the threads - will show. Hopefully it won't show through the PR too much. 

Dan


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## apple320 (Dec 30, 2009)

*Another one I found*






Same idea

Chris


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## cnirenberg (Dec 31, 2009)

Chris,
Excellent idea.


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## ldb2000 (Dec 31, 2009)

I guess I have been lucky so far , I thread PR all the time and haven't had many problems . I use taps and dies to do all my threading and get nice clean threads , both inside and outside . Like this one 





I do try to reinforce the inside threads with some kind of centerband , but even with out the CB I have had good success , like this 



 

The cap threads on this pen are cut in the PR and a metal threaded coupler threads into them , so far the threads are holding up just fine and these are both pens that I use on a regular basis .


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