Esterbrook and Osmoroid Nib unit Thread size

[rnfuller]

I came across several Esterbrook and Osmoroid nib units, and would like to make some sections to use them in some custom pens.

Does anyone know the size tap needed to thread the sections for these nib units?

Thanks
Randy

 

[BRobbins629]

Many of those are odd sizes and multi start, so more than likely you will either need a custom tap or use a CNC. I usually look under a microscope with a steel rule and estimate the #/in and look carefully to see how many start places, then measure the od with a caliper. For sections, this is usually close enough. I have also done some with just a friction fit and they work as well.

 

[ldb2000]

Send a PM to Chris (apple320) , he has used estie nib units on several pens and will most likely know what the threads are .

 

[Chthulhu]

The major diameter is 0.280 inch, and the pitch is 36 tpi for the Esterbrook Renew-Points. A 9/32-36 tap *might* work if you can find one; it's not a standard thread. I've read that the Osmiroid units are the same, but haven't confirmed this.

Note that the Esterbrook units are designed to seal with the edge of the feed end of the outer sleeve tight against a 45 degree chamfer in the bore of the section, below the threads. I've found silicone grease on the threads to be an effective alternative to that chamfer.