Cracked Wood

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lawrence

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Jun 29, 2018
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Location
Sugar Land Texas
But here we go I made 4 pens for 30cal bolt action kits 2 out of Red Palm 2 of Granadillo. Used 20 m1n Epoxy cured 4 days in my shop during this time the temperature swing was 35F- 65F. The day I turned the pens and finished them 50-60F with slow rain... Ca finish only. All 4 developed a crack 100% along the length of the wood.
 
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It sounds like your wood was green, i.e. not yet dried. Until most woods are dried sufficiently, they will expand and contract, some much more than others, even when dry. In most cases, it is the moisture loss or gain (humidity fluctuations) that causes expansion and contraction that results in cracking. If I suspect a blank is not yet completely dry, I will microwave it for a minute, let it cool down and microwave it again for a minute. I will do this several times. (that is my general procedure, not the specific one.)

Mesquites is one of a few woods that don't do dimensional expansion and contraction as most woods. The more brittle wood is, the more it is subject to cracking also.

One other possibility. Noticing that you are relative new to pen turning, getting a small amount of glue inside the tube and then assembling it - that can and does cause cracking. In most cases it is instantly but in some cases, there is just enough expansion of the tube that with the first sign of humidity change or heat, suddenly it will crack - sometimes for the whole length. But in your case, this probably did not happen since all 4 did that.
 
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It could be one of several things, or a combination of several things. First when you drill the blanks, you heat them up, some woods will crack just because of it got too hot. Green wood? Possible, but my guess unlikely but you are on the coast, your normal high humidity is absorbed by the wood, because wood likes to equalize with the local atmosphere.

Natural stressors inside of the wood are released when you drill, causing wood movement inside of the hole. This sounds like "hocus pocus" but pool cue makers like to remove small amounts at a time over days and weeks so that the internal stresses can be released so that the final product is perfect. Wood moves on it's own caused by both heat and humidity.

You moved them from the shop an uncontrolled enviroment to you house, which has heat and air a controlled enviroment. Part of the equation?

Some woods are just finicky and prone to doing strange things that are not explainable. My explanation for that is shop "gremlins", they are little unknowns that keep doing things to us to keep life interesting.

In short, sometimes things just happen.
 
I've never turned a green wood blank before. But I know when you turn green wood, it needs to set and dry for a period of time, depending on the size of the project. If your wood was green and you coated them with CA glue, the glue may have prevented the wood from moving while drying. May have forced them to crack.
 
My understanding is that palm is pretty stable. It isn't actually wood and doesn't have growth rings, so it swells and shrinks evenly. If all four blanks were from the same supplier, then it's possible that they were not yet dry. Typically suppliers will warn customers if the wood is still wet, but pen blank sizes should dry within a few weeks, so I'd say it's not a common problem (with purchased woods). Are the cracks all the way down to the tube? A pic of the failure might be helpful.
 
Cracked Pen blank is attached
 

Attachments

  • SPLIT PEN.jpg
    SPLIT PEN.jpg
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this was mentioned above and I am betting difference in humidity in the house and the shop. Carefully examine the wood cutoffs - are there any fine cracks in it? If so could be enhanced by heat from drilling and humidity/temp changes between the house and the shop
 
:redface:
lawrence said:
Cracked Pen blank is attached
Click to expand...

That is a humidity/heat crack. You said earlier that they were in a box. Were they in a room with a window and placed near the window so that sunlight might shine on them. Usually that type/size of crack pops up when a pen is placed near direct sunlight and short periods of quick higher temps are reached - such as in a hot car or in a glass case in which sunlight is able to hit on it for an hour or so.

It does not have to be that situation as other situations can cause it. I did not read that you took it into your house, (I missed that). Changing the environments for furniture that is made in unheated and non-environmentally controlled shops causes home made furniture to crack also. I would say - that is exactly what happened to your pens.

I lived near the coast in Japan for 25+ years and humidity played a big role in the way I did my woodworking and later my pen turning. I experienced the humidity cracking in wood in my earlier years - from wood that had been air dried for 10 years or so. My shops in my earlier years were not heated or cooled and humidity/temp changes was something I learned to adjust to and avoid when possible. As to pen blanks, I mentioned previously that I would microwave some blanks slowly or put them in humidity stable environments for a few days before using them. Sugar Land - Coastal area, that will affect some blanks and the thinner they get, as in a turned pen, the more likely that will happen.

One more bit of information: Consider this a big plus. If you start selling or just making and giving away pens, You learned early on what happens, and it happened before you sold them or gave them away. Better to happen at home than having your reputation tarnished. :redface: I have been there and done that.
 
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I too am dealing with cracking, but with some Osage orange I cut last spring. I'm experiencing cracking as I press the ends of this magnetic graduate kit. I've made this body of the pen three times. After the first one cracked, I microwaved the blank a couple of times, thinking it was still too green. The third one I slightly over sized the ends and tried to make sure all the epoxy was more in the middle.

Here is what I started with.
IMG_3634.JPG

Here is the crack.
IMG_3638.JPG

Each time I ensure there is no epoxy in the tube, I thought oversizing the blank on each end would give some room for tube expansion. Maybe I'm fighting the tight cross grain. I applied a nice CA finish, is that causing it to crack? This time it was just one end.

I plan to press it apart and try one more time, any suggestions?
 
Depending on your source, some blanks you get may be sealed with wax. If they are then most likely they are not completely dry.

Also, if you glued in the tubes immediately after drilling you may not have given the wood sufficient time to cool and move after drilling. With some woods after drilling and cooling you will notice the tube is a very tight fit and you need to drill the hole again. That is from the wood contracting and moving.
 
TG Design said:
I too am dealing with cracking, but with some Osage orange I cut last spring. I'm experiencing cracking as I press the ends of this magnetic graduate kit. I've made this body of the pen three times. After the first one cracked, I microwaved the blank a couple of times, thinking it was still too green. The third one I slightly over sized the ends and tried to make sure all the epoxy was more in the middle.

Here is what I started with.
View attachment 185473

Here is the crack.
View attachment 185474

Each time I ensure there is no epoxy in the tube, I thought oversizing the blank on each end would give some room for tube expansion. Maybe I'm fighting the tight cross grain. I applied a nice CA finish, is that causing it to crack? This time it was just one end.

I plan to press it apart and try one more time, any suggestions?
Click to expand...

Perhaps after disassembling it. You can get some CA to flow into the crack and clamp it until its closed then let cure overnight.
Next I would unclamp the body and take a needle pile to the inside of the brass tube until you can work it down until you're hardware slips in withought resistance. Then glue your hardware in using CA or a thin epoxy.
Place whatever type of adhesive on the inside of the brass tube. Not on the hardware end or the excess glue will squeeze out and make a mess. Very little adhesive is needed. Apply a small amount with a tooth pick. I prefer a 5 min epoxy which is a little more time forgiving.
I usually use this technique when working with a very thin pen body end or brittle material such stabilizes buckeye.
Good luck!
-Anhony
 
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