Help with Pen Blanks

[Paul Ray Moore]

My son turns these celtic knot pens from ebony and holly. I recently purchased a block of ebony 3" x 3" x 12" from woodcraft and cut it up into pen blanks for him. I've used these blanks before from woodcraft and have had no problem but on this set all of the pens cracked after he turned them. He then bought some ebony pen blanks from Bell Forest Products. He has turned 2 from these blanks and they have both cracked.

The woodcraft blank was waxed and so I originally thought that there was too much moisture. So we ordered what were called pen blanks from Bell forest and they came in waxed. We've checked the ends with a moisture meter and they are around 9% so I'm not sure that is the problem.

He originally assembled 3 or 4 and brought them in the house. After being inside for a couple of weeks he looked at them and saw the crack. Then he turned some more and they did the same thing. Thinking it might be the drier air in the house he turned one and left it in the shop unfinished but it also cracked.

Any suggestions? He has turned 9 and it is getting kind of expensive for him.
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[James Combs]

Regardless of what the moisture meter said the problem definitely sounds like wet wood especially since both vendors supplied it waxed.

You don't show any details of how they are being finished. I doubt that the finish is the problem but give us some details on how you are finishing them, perhaps we may see something you are missing. However, my money is still on it being wet wood.

Just a thought, take one of the blanks before it is turned and run it through a drying process such as "lightly" micro waving and weighing until it stops loosing weight or do a DNA soak for a day then let it air dry for a week.

Keep us up-to-date as how it goes and what you did if you solve the problem.

[Jon Behnke]

Pens made of Ebony are notorious for cracking as you've unfortunately found out. I've heard that if you drill the blank with a slightly smaller bit, set the blank aside for a few days and then drill with the correct bit it allows the blank to dry more evenly, lessening the chance of cracking. I've not tried this myself but it might be worth trying. The other option is to use African Blackwood instead of Ebony or else a black resin, either will achieve a similar look which makes a sharp looking pen. By the way, Leopard wood is known for the same issues.
Good luck.

[Paul Ray Moore]

We are using BLO and medium CA. Good idea on the DNA or microwave. I think I'll use the DNA because I don't think my wife will let me use the microwave in our house. Maybe I'll take it to the work microwave. Think anyone will notice?

[Dan Hintz]

I would microwave it, then turn immediately after it cools.

[Jim Seyfried]

I was thinking heat in the process might be cracking them too. Seeing that he has successfully made them before could the drill bit be getting dull and producing more heat? Just a thought.

[Dale Gillaspy]

It is a possibility as well. I have had that happen to me, but usually I notice it right away and yell out some choice words your son probably shouldn't say.

[Brian Brown]

I would be very careful with the microwaving. Ebony hates heat. If you do try , very low power over an extended period of time. Don't let it get very hot. I am thinking that the drilling might be the problem. We tend to start slow and cautious with anything new, then when our confidence builds, we work faster and more aggressively. I wonder if he is pushing the drilling of the blanks too fast, and causing a heat build up. This could be causing micro cracks in the wood that enlarge when the wood gets really thin during the turing process. One possible solution would be to slow down the drilling process, and drill the blanks once or twice with smaller diameter bits, working up to the final bit size. This produces less friction on the last bit diameter, and less chance of cracking. I hope he finds a solution, Those are very nice looking pens.

[Jim Burr]

As a thought...try drilling it, put the shavings back in the hole and put the blanks in a Ziploc style bag. See if you can mediate the moisture release. Every chunk of ebony I have was received un waxed and dry as a bone so I am probably of no help. When doing bowls and mill blanks that are still a little damp...I do the bag thing. Maybe worth a shot?

[Tim Browne]

Seeing those pictures I also thought of a heat problem while drilling. Another thing to check is a dull trimmer head. I had one that suddenly went dull and ruined so many blanks I almost stopped making pens. Once I figured out the problem and replaced mine the love and joy have returned.

[Richard Coers]

You can also crack the wood from sanding. Dull paper and too much pressure will crack exotics every time.