# Threads not concentric



## Simplex (Nov 29, 2011)

For those of you who cut your threads with a die like I do, I was was wondering if you ever had an issue with your threads not being concentric.  I recently finished one of my kitless fountain pens and when I screwed on the cap I found that the cap was shifted off to one side of pen more than the other.  From what I can see, my die will not sit in the holder in a way that aligns the center of the die to the center of the die holder.

Does anyone else have this issue?


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## Dalecamino (Nov 29, 2011)

If there is an adjustment screw in your die, it could be sticking out just enough to prevent the die from seating into the holder. I took a small file and, cut a groove in the holder wall. Just a guess.


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## soligen (Nov 29, 2011)

Try making an "on ramp" where the die engages the blank to cut threads.  This on-ramp helps align the die to the blank (assuming your tail stock is not locked down).

See my tutorial on bulb filler that was just posted for an example


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## mredburn (Nov 29, 2011)

Which die are you using that is giving you problems? Or is it the same for all dies?


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## Simplex (Nov 29, 2011)

It appears to be all dies.


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## 043Turning (Nov 30, 2011)

if the dia is not secured, to prevent it from moving off centre then one thread will start to cut before the others and this will pull the threads off centre  

A longer lead and one of these http://littlemachineshop.com/products/product_view.php?ProductID=2314&category=

 should fix the problem


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## Russianwolf (Nov 30, 2011)

Are the threads consistent around the piece? If it is truly cutting off center you will have threads that are fully cut on one side and on the opposite side the threads will be less than fully cut. 

The other possibility is that the cap was drilled off center. So check to see if the sides of the cap have a consistent thickness.


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## Simplex (Nov 30, 2011)

043Turning said:


> if the dia is not secured, to prevent it from moving off centre then one thread will start to cut before the others and this will pull the threads off centre
> 
> A longer lead and one of these http://littlemachineshop.com/products/product_view.php?ProductID=2314&category=
> 
> should fix the problem



I had to laugh when I opened the link; this is exactly what I use right now.  I have noticed that the diameter of the die is sufficiently smaller than the diamter of the die holder such that the center of the die does not align with the center of the die holder.


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## glycerine (Nov 30, 2011)

Simplex said:


> 043Turning said:
> 
> 
> > if the dia is not secured, to prevent it from moving off centre then one thread will start to cut before the others and this will pull the threads off centre
> ...


 
Gary, I noticed the exact same phenomenon with some of my dies in my homemade die holder (which is much like the LMS one).  What I did was took an empty soda can and cut a few thin strips as shims and wrapped these part way around my die before inserting it into the holder.  (I do this on the opposite side as the set screw, obviously because if the die will be off center, it will be becasue the pressure of the set screw is pushing it off center.)  I am able to get the dies centered and haven't noticed any issues so far.


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## RichF (Nov 30, 2011)

I used a similar approach as mentioned above.  I shimmed my dies with a couple of small strips of aluminum tape so it rests centered in the die holder.


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## Curly (Nov 30, 2011)

Simplex said:


> I had to laugh when I opened the link; this is exactly what I use right now.  I have noticed that the diameter of the die is sufficiently smaller than the diamter of the die holder such that the center of the die does not align with the center of the die holder.



There are two ends to that holder, one for the 1" die diameter and the other for the 13/16" die diameter. By any chance is your die the smaller one and you have it in the bigger end?


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## Simplex (Nov 30, 2011)

Curly said:


> Simplex said:
> 
> 
> > I had to laugh when I opened the link; this is exactly what I use right now.  I have noticed that the diameter of the die is sufficiently smaller than the diamter of the die holder such that the center of the die does not align with the center of the die holder.
> ...



I thought about that, too, but the die does not fit into the small end.  Like the others, it looks like i will be shimming the die.


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