Cracked Caps

[walshjp17]

While at a local woodturners' meeting today, a guest asked me about a problem he had with two of the pens he recently turned. One is a Cambridge Deluxe (Woodcraft) in Desert Ironwood and the other is an Olympian Elite (PSI) in an unknown species. The pens seem to be variants of each other.

A week after turning each pen, a crack about 1/2" long appeared at the top of each cap end -- see the photo. The crack on the Olympian is actually wide enough to see down to the brass tube. I asked if he had any problems during preparation, turning and/or assembly and he indicated there were no issues.

So, if anyone has experienced similar post-production problems and may have some sort of solution, please let me know so I can pass the info along.

BTW, I believe he will be joining IAP soon.

Apologies for the photos - poor lighting, iPhone and poor backgrounds in the meeting woodshop.

 

[thewishman]

Was the wood dry? Was there junk in the tube? Big swings in temp or humidity?

 

[Haynie]

Moisture in the wood?

 

[ed4copies]

1) Did he use a pen mill to square before turning? (This can crack the wood)
2) Did he thoroughly clean the tube of all adhesive from the glueing in process?
3) Did he insert the clip and "clip bushing" (from instructions) straight, or were they somewhat cocked?

IF ALL of the above were done properly, THEN the question of humidity, "green" wood, etc can make this happen.

In short, when making a "better" pen (read more expensive kit), it is wise to slow down and do everything as conservatively as possible. This means drill the blanks and let them sit in your shop for a week to acclimate. AND, swill thin CA in the hole a couple times during the week to reinforce the wood that will become the pen (you turn off the outside, reinforce the INSIDE!!)

Or, make it quick and it might crack.

 

[Justturnin]

Looks like the fit for the component into the tube was much to tight. Did it take a lot of force to get it in? Possibly glue in the tube or the tube ID just needing to be opened up a bit. I like to be able to almost hand press the parts and use a drop of Loctite to hold them together.

 

[JohnGreco]

Interesting. I just had a customer contact me that a Majestic Jr I made a couple months ago in Ironwood cracked on the cap. This wood is OLD so it was as dry as it was going to get. First time I've had this happen aside from ebony which I really hate to work with.

 

[jttheclockman]

When will it ever become aparent to people who work with wood that wood moves. You are locking a moving object to a solid object the tube with glue that becomes hard as a rock when cured. Some woods are prone to cracking more because they move more. Even though the piece of wood we use is so small it is so thin on the ends and that is one of the reasons you see cracks on the ends. Put the pen in an atmosphere where the temp changes alot or the moisture changes alot cracks will happen. It is wood.

Things like Ed mentioned can also cause cracks so it is hard to pinpoint exactly why this happened and what to do to stop it from happening. Alot of people think if they put a finish coat such as CA on top that would stop this movement but they never seal the ends of the blank and expect miracles.


From the photo it looks like the cracks happened down grain lines. Good luck trying to stop that. More closed cell woods such as mahagony will tend to crack less.

Just an opinion

 

[Neededwill]

I had Burmese rosewood do the same thing along the grain. I made 2 pens and they both did it 2 weeks later when I was inspecting them before giving them as a gift. I just think the grain expanded.

 

[walshjp17]

Thanks, everyone. I appreciate your comments. I wil pass them along.

 

[JohnGreco]

When will it ever become aparent to people who work with wood that wood moves. You are locking a moving object to a solid object the tube with glue that becomes hard as a rock when cured. Some woods are prone to cracking more because they move more. Even though the piece of wood we use is so small it is so thin on the ends and that is one of the reasons you see cracks on the ends. Put the pen in an atmosphere where the temp changes alot or the moisture changes alot cracks will happen. It is wood.

Things like Ed mentioned can also cause cracks so it is hard to pinpoint exactly why this happened and what to do to stop it from happening. Alot of people think if they put a finish coat such as CA on top that would stop this movement but they never seal the ends of the blank and expect miracles.


From the photo it looks like the cracks happened down grain lines. Good luck trying to stop that. More closed cell woods such as mahagony will tend to crack less.

Just an opinion

I get what you're trying to say, but I think there was a better way to say it without coming across the way this does. No need to be condescending, ending with 3 Smiles doesn't change the words you chose.

 

[walshjp17]

Many Thanks

From the person who asked the question in the first place: "Thanks. I really got some great ideas that I will try."

 

[Mintman]

John,

There were some very good potentials listed above. I have found the single largest cause to be to much glue in the tube. Since I have started plugging my tubes with dental wax, I have not had a single tube crack. Just my 2 cents.

 

[walshjp17]

John,

There were some very good potentials listed above. I have found the single largest cause to be to much glue in the tube. Since I have started plugging my tubes with dental wax, I have not had a single tube crack. Just my 2 cents.

Actually, the first question I asked him was how he glued the tube in. We discussed a few options.

Plugging is a good idea. I have used potatoes in the past but now use Play-Doh.