Cross threading when fitting cap

[ibex]

I've been having trouble when people are looking and trying some of my pens at sales, and sometimes they end up with the cap cross threading slightly when they put it on the body. It's easy to turn it back a third or so and restart it but it gives a poor first impression of the the pen.

I presume I'm doing something wrong with the fit of my cap and body threads but I don't know where to start.

I am using Tapco M13x0.8 and M14x0.8 taps and dies and the blanks are typically either from Just Turning in Australia or TurntPenCo.

I've included some photos of two of my pens so maybe you can see what I need to do differently.

Any help would be appreciated.

 

[hooked]

It looks to me like you need to put a radius on the end of your tenon and possibly chamfer the inside edge of the cap. At least from what I see on the blue section.

Doing so with help create a smoother start to the threads and guide the two pieces to join properly to help avoid cross threading.

 

[NJturner]

I agree with @hooked - you need to give a bit of a 'runway' for the two parts to align themselves to prepare for turning. A chamfer or radius on the body would be my first step - allowing the cap to align with the threads as it is pushed forward on the body. The goal also should be to have a corresponding 'receiver' thread on the cap, so you have leeway for alignment before threads come into play.

The pics you provided show the thread starting immediately, without any space to help the cap be aligned before it hits the threads. Providing a non threaded area that brings things into alignment, even if you reduce your threading a bit, will cut back on the cross threading and ultimately help things last.

Kevin

 

[mredburn]

May I ask what diameter your tenon is and the size of the hole you drilled for the different sizes?