Not sure what happened

[Madman1978]

I actually turned this pen last week. Was no cracking when I assembled this one. I just went to use this, twisted it and it cracked and the nib fell out
Any idea why this could have happened?

 

[egnald]

What material is that? It is very dark and what did you use to glue the tubes in?
Some materials crack much easier than others - horn for example and ebony woods especially if they are not dry before being turned.
Dave

 

[carlmorrell]

Is it ebony? I got a nasty crack in ebony. But it took a few weeks to show up. Ended up filling the crack with turquoise and made it my daily driver. This pen is well over 20 years old:

 

[Madman1978]

I believe epoxy. It looked wonderful until it cracked!

 

[nobodyparticular]

What strikes me as odd is that both turned parts cracked at the same time and it seems in a similar place (unless this is a pen unlike any I have seen so far and assembled from a single tube?), which makes me think that the tubes may have caught when you twisted it. Maybe the transmission was/is stuck, causing excessive twisting force?

 

[leehljp]

I actually turned this pen last week. Was no cracking when I assembled this one. I just went to use this, twisted it and it cracked and the nib fell out
Any idea why this could have happened?

Quite common. Ebony! Pen turners have been asking "Why" for years!

Ebony as a blank can crack but usually doesn't. Extreme care in drilling "seems" to help some, but that doesn't prevent it. My opinion is that it needs to be drilled 1/64 inch too large and use flexible glue. Ebony, under heat or cold or wide humidity changes does NOT like to be constricted. Ebony will fight constriction. 1 in 25 or 1 in 50 will not crack under wide changes and there is always one person that says theirs has not cracked under wide environmental changes. But in most cases, it is a given that it will.

Why do unturned and undrilled blanks not crack as much as those on pens? They can expand and contract on their own; Drill them out and constrict them with glue and nature will win. That is the nature of wood.

Your Pen: The fact that they both cracked on the same side "suggests" that they probably received too much heat equally - Sunlight, heater? Then again, it might be that you aligned the grains perfectly in their natural line and that was the weak spot.

More on this phenomena: laminates and plywoods do not expand and contract like solid wood. 3/4 inch plywood will be virtually stable. 3/4" thick red oak, cherry, white oak, walnut will expand and contract considerably, especially on a board 12" wide and 8 ft long. I have had boards crack when glued together side by side and then screwed down. Wood moves and likes to move.

 

[Sly Dog]

I'm guessing here but sometimes there is a hairline crack in a blank that you just don't notice until it fails. The crack in your pen extends the along the grain the entire length of both blanks (which I assume were once part of the same). The finish doesn't look like CA so did you use friction polish? How long after assembly did you attempt to use it? Maybe drilling and/or heat from finishing just accelerated the failure. Too bad - nice pen!

 

[magpens]

Too bad .... nice pen otherwise !!

Above suggestions seem plausible to me. . I know from experience that ebony is almost a sure bet to crack where others won't.

As already stated ... drill oversize and use a flexible, non-expanding glue.

I would also be very careful when drilling so as to minimize heat.

Sorry you have this problem ...

 

[sbwertz]

Every pen I've ever made from ebony eventually cracked.

 

[MRDucks2]

I was gonna say I had an ebony pen that hasn't cracked in 3 years. BUT, I pulled it out of the pen drawer to verify and there are 2 hairlines, one coming in from each end. Unlike snakewood, where a hairline can remain hidden in the complex grain, it it more easily noticed on the ebony.

Also, it is noticeably a wood blank and likely ebony as everyone has noted. Part of making pens well is to understand the materials you are working with. Even among resins, they have different properties and the variation among woods from around the world is huge. Some are pretty forgiving and others, not at all.

 

[PatrickR]

I would qualify that as a "check", leading me to guess that the wood was not dry when turned. If it is waxed, consider it "green" if not waxed give it plenty of time in a non climate controlled area to dry/acclimate to your local conditions before processing.


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