TUTORIAL: Step-down tube size, increase casting clearance

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SteveG

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Dec 21, 2009
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I mentioned this process in another thread and was asked to post a tutorial. I am working from memory, presenting something I did about four years ago. The pen photo is not the best, but all that I had. :frown: This pen photo was cast with highly treasured Hawaiian Ni'i'hau shells, set in the form of a shell lei against a beach sand background. There was not enough depth available in the standard Zen kit, so I stepped down the tube size to an 8mm tube. This is the smallest tube that would accommodate the RB refill. It provided just enough depth to cast the small shells and sand.

The process:
1. By trying different tube sizes, I was able to find tube diameters that would nest nicely. I recall having to sand one of the tube segments slightly to get it to fit inside the next size up. The step-down tube segments were each about 3/8" in length.
2. I used epoxy to glue the tube segments together. This proved to be strong enough. Note that I did sand the normally-pressed-in kit components to a slip fit, then epoxied them in. This was done to avoid stressing the step-down glue joints.
3. The tube joint glue-up was set in a V-grove block to cure, ensuring straightness of the tube assembly. The overall length was made slightly over-size so the tube assembly could then be sanded back to the exact length of a standard Zen tube.
4. For this pen, I glued the two precut wood blank segments in place with the 'show' ends sanded square and smooth. Then the exposed 8mm tube was coated with sand, followed by gluing on the shells. Once everything was cured, I partially wrapped the area of the sand/shells in a 'U' shape with some heavy paper, and did a no-pressure clear cast.
5. The blanks made this way all worked fine, with no failures. I was cautious to not over tighten the tailstock when turning, keeping in mind the tube glue joints.

Comments: The step down could have been accomplished by turning/drilling a small filler piece from hardwood or brass. Also, the brass (tube segments or filler piece) could have easily be soldered instead of using epoxy. I eased the internal end of the 8mm tube prior to assembly to make it easier to insert the refill. This process can easily be adapted to a number of component sets, but a pen cap would need close attention to internal clearance requirements. My personal preference is for the Zen to be turned straight, no bulge. I did in fact turn the blank with a slight increase along the length (save the shells margin) that is not noticeable visually.

Oops, photos disappeared...will fix.
 
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jttheclockman

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Feb 22, 2005
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Steve thank you for doing this. I have saved this thread and will diagnose this. This could help in many different kits and expand some ideas. I was hoping you would post. Very well done. I do not believe we have a library attendee any more so probably will not make it there but this is good too because of your title.
 

leehljp

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Back in my model car and airplane building days in the early 60's, I used to get several successive sized tubing and make increased/decreased connections. Only I used solder.

Works well and easy to do.

I have numerous successive mm size tubing from when I was overseas. And it helps when making kitless pens as well as wanting to increase the wood thickness for various reasons. IN those cases, glue is your friend instead of solder.
 

jttheclockman

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Feb 22, 2005
Messages
12,343
Location
NJ, USA.
Back in my model car and airplane building days in the early 60's, I used to get several successive sized tubing and make increased/decreased connections. Only I used solder.

Works well and easy to do.

I have numerous successive mm size tubing from when I was overseas. And it helps when making kitless pens as well as wanting to increase the wood thickness for various reasons. IN those cases, glue is your friend instead of solder.

I just got my delivery from Exotics which I bought all size tubes he had in 10" lengths just for this kind of stuff. Will be playing with the idea in the future.:)
 
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