Splitting/cracking - frustration

[mwildes]

I wrote a few weeks ago about an African Blackwood Majestic that came back with several splits in the cap. Yesterday, I got back a Cocobolo Designer with cracks in it. The Designer was made in late August and the customer said that the cracks appeared within the last few days. The Majestic also took several months before cracking.

Has anyone else had cracking problems after this length of time? I am assuming (not a good idea) that if the wood were not dry enough, that it would crack much sooner, since when turned, it is only a few sixteenths of an inch thick.

One thing that I will begin doing is checking all pen blanks with a moisture meter: on the exterior, as well as on the interior once they are drilled. What are opinions on proper moisture level? Is 10% - 12% dry enough? Or should a pen maker invest in a food dehydrator and get it lower?

Thanks in advance for any help and input.

 

[Daniel]

If wood is going to crack, this would be the time of year for it. winter is the driest time of the year. I stay with stabilized woods as much as possible. although there is no such thing when it comes to either African Blackwood or Cocobolo. I have noticed this a couple of times when I turned blanks that I had in my shop for only a few days. now I let them set for a month or even more. ended the problem for me. I don't think I have ever had Cocobolo crack though.

 

[GouletPens]

what kind of finish do you use? if you're using a shellac base or something like that, then it would wear off after a couple months (or sooner really) and be very susceptible to moisture level changes. If you use CA or plexi it would help with that. Even with the moisture meters though, you're probably not going to get a very accurate reading on a pen blank. You usually need to have wood at least 2" thick to get an accurate reading with meters.

You might want to just try microwaving your wood. Weigh the wood, nuke it for about 2-3 minutes on LOW power, weigh it again. Let it cool, and repeat until the wood doesn't change weight anymore. That's when it's dry enough to use. Even still though, you can't control what happens to it after it's sold. I think a good disclaimer might help you here to, if you don't already have one. Unfortunately, wood is going to continue to move, forever!

 

[ed4copies]

Marty,

I cannot offer a good answer, cause I have the same problem.

What have I done to address it? Turn mostly Acrylic and polyresin - our blanks don't crack (once they are properly drilled and assembled).

Did I mention I SELL plastic blanks?????

 

[Daniel]

Ed, I am following quickly in your foot steps. I use almost exclusively stabilized woods though. but after all the years of making these novel wood pens I am thinking that really nice pens are Acrylic or Celluloid.

 

[marcruby]

Certain woods crack, not just because the wood expands, but the metal tube does as well, and for different reasons. I've found that the best solution is to drill slightly loose and use epoxy as my glue. Don't drill blackwood or ebony that isn't dry, and let the drilled blank set for a while (like a month) in dry conditions before gluing in the tube

 

[mwildes]

Thanks to everyone for your help. The African Blackwood Majestic was finished with 3 coats of Waterlox and then the 3-step Beall system. The Cocobolo Designer was just the Beall system, minus the white diamond step.

I'm learning the CA finish process and maybe this will help. I'm intrigued by and plan to attempt the melted plexiglass "dip". Has anyone attempted the "Deft" finish dip? Is this an acrylic type coating?

The suggestion to limit usage to stabilized blanks may be the way to go, along with using acrylic blanks. Yesterday, I just received my pressure pot. So the world of casting has just opened its doors to me too. Did everyone's wife look at them weird when they first saw the pot with all the valves and fittings? Now she REALLY wonders what is going on in the shop! HA!!

Thanks again for all your help.

 

[ed4copies]

Marty,

I have a BEAUTIFUL CA-finished BOW pen. Took less than a month to develop one crack on each barrel.

I DO wish you luck, but I haven't had any!!

 

[andyk]

Most flatwoork usually runs in the 6% - 8% range. Optimally there should an equilibrium between the wood and the environment to limit shrinkage and expansion.

 

[leehljp]

Cracking can be caused by several things and then a combination of things too. Looking for "one" culprit is not necessarily going to solve the issue.

Causes:
1. Humidity changes;
2. Dramatic Heat/Cold;
3. Heat built up during drilling;
4. Non stabilized woods of different kinds;
5. "Green" wood as in high moisture content, especially with cross grain cuts;
6. Too tight of a fit between blank and tube (doesn't allow microscopic expansion/contraction;
7. IMO and a theory - in some cases, especially on brittle woods - a flexible barrier is needed between the tube and wood. Differential expansion rates of brittle wood and metal tube/hard glue can cause cracks.

 

[mwildes]

Thanks again to everyone to take the time and offer their experienced opinions. For now, I think I will change from CA to epoxy for tube glue and I will drill 1/64th larger than what each kit calls for. Hopefully, this will give the wood a more flexible foundation, yet keep it affixed to the brass.

I will also work more and more with purchased acrylic and cast PR blanks. Although I can foresee plenty of shop made blanks, I don't foresee a significant decrease in wood blanks. I'm a wood guy, the look and feel of wood can't be beat, IMHO.

As far as customers go, perhaps a limited time replacement warranty. Of course it would include the same species of wood, but a grain or pattern match could never be guaranteed. I think I would have to offer something in case a crack develops in a short period of time. I know that as a customer, I would expect at least a short warranty. Maybe a 4 or 6 month warranty, and add a pen "registry" to the website that they would have to complete to activate the warranty. Is this reasonable?

Thanks again!

 

[NewLondon88]

For now, I think I will change from CA to epoxy for tube glue and I will drill 1/64th larger than what each kit calls for. Hopefully, this will give the wood a more flexible foundation

I know that as a customer, I would expect at least a short warranty. Maybe a 4 or 6 month warranty, and add a pen "registry" to the website that they would have to complete to activate the warranty. Is this reasonable?

Thanks again!

I think that extra bit of room is a good precaution. Some of the kits are
drilled to a pretty close tolerance, and CA makes an unyielding gap filler.

Unfortunately, you can't control how the pens are cared for once they
leave your shop. The registry is an interesting idea.. I'll bet that it raises
the perceived value of the pen immediately. But . .how to track them?
Serial numbers for your pens? Or perhaps there's few enough to just keep
track? But the registry idea sounds good.

The only pens I've had the cracking problem with have all been related to
heat and/or moisture. I made a lot of amboyna pens from a large block I
got at a retailer. While they looked stunning when they left the shop, they
ALL came back cracked after a few months. A couple of ebony pens did
that, too. I learned to nuke first, weight the block before cutting into
blanks (and if you cut them first, cut WAY oversized!) and let them sit
quietly on a shelf for a while.

 

[GouletPens]

Certain woods are worse than others, as well. Even with the correct moisture, a lot of the denser woods are going to want to crack before others: tulipwood, amboyna, bloodwood, end especially gabon ebony (black) among others. It's just always a risk, and you can't really control how they're treated after you sell them. The registration idea is interesting....

 

[Randy_]

It's interesting you are having trouble with African Blackwood. That is a wood that is recommended to substitute for Ebony as it is supposed to be more stable than the highly unreliable Ebony. Russ Fairfield posted some thoughts on the cracking of Ebony. Don't know that I agree with everything he says; but there are certainly some interesting things to think about and he claims to have nearly a 0% failure rate. Do a search of the IAP threads and read his comments. Post if you can't find it and someone here will point you in the right direction.

This subject has intrigued me for quite a while so I thought I would dip my toes in the water. I just bought a few blanks from Nolan.....Ebony and Snakewood....and am going to try an experiment or two for myself. I have a couple of theories I would like to test. Can't do as much testing as I would like.....at 8 bucks a blank for snakewood, it gets a little expensive!!

Nolan assures me that he puts a moisture meter on all of his wood and it is properly dry. In spite of that, I intend to let the blanks sit for a month before I drill them and then let them sit for another month before I turn them.

I weighed the blanks when I first got them and will weigh them again at the end of the month to see if I can detect any weight change. I really don't know a lot about wood; but can speculate that oily wood like Ebony might take a lot longer to dry out than your average wood. Maybe letting it sit for two months is not enough; but I will start there and see what happens. As I recall, the wood Russ was using has been sitting around for 10 years.