Why do my bloodwood pens keep cracking?

[Dvoigt]

Why do my bloodwood pens keep cracking?

I have done a several pens recently in bloodwood and evreyone of them has cracked, I have not seen any cracks in other pens (knock on wood). Half of them I noticed the cracks right after I assembled them and the other half I noticed later on. I use a 2 part epoxy to glue the tubes in the blanks. I tried sealing the ends with some this CA, when I turned the pens down near to the final shape I coated it in thin CA in the hopes that it would sink into the grain and strengthen it. I tried drying the blank in the microwave... What else can I do to try and stop this?!

Thanks
Derek

 

[marcruby]

Certain woods - bloodwood, ebony, blackwood, etc., have very dense grains with very little flexibility. Since brass and these woods have different coefficients of expansion vs. temperature and moisture they are very likely to crack. Say if the wood shrinks and the brass tube doesn't. I've also seen claims that turning heat can lead to cracking. I'm not convinced of that, but it certainly is a possibility. If that's the case then CA setting heat might be a problem when finishing.

The wood shrinkage is caused by loss of oils, not water. So a pen can be fine for months and then, suddenly, crack from building pressure. It's important to allow the wood to season in a dry atmosphere for as long as possible.

In construction you want to weaken the connection between the wood and the brass. Drill the hole a bit bigger for a looser fit. If possible, use a flexible epoxy as your glue. Work with dry wood and leave plenty of time at each stage to allow the wood to adjust. Avoid sudden temperature changes.

Even then you will get some breakage. Leave enough wood initially so that you can resand and fill the cracks before final turning. Obviously part of this is that you can't make a rush bloodwood pen.

Marc

 

[spiritwoodturner]

Try snakewood someday for some real fun...

And when did you microwave it? I'm not a fan of "cooking" wood, and wonder if that may have altered the grain enough to be a problem. I've never had a problem with bloodwood or ebony or blackwood myself, but I guess there's a first time for everything. Snakewood's the only one I've had consistent problems with.

Dale

 

[YoYoSpin]

Oily woods + heat = bad

 

[rick_lindsey]

Would stabilizing the blank help in this case? I haven't turned it yet, but the next blank in my "queue" is a bloodwood slimline... I've already glued the tube in this one so it's too late to stabilize, but I've still got a fair chunk of bloodwood left.

-Rick

 

[marcruby]

I don't think stabilizing would help. Dense, oily woods don't allow much penetration of chemicals.

Marc

 

[rick_lindsey]

Thanks, Marc. I assume leaving more wood might help alleviate the issue? I was planning to turn it as a "fatline" anyways... it will still be thin at the nib end though.

-Rick

 

[YoYoSpin]

If you don't nuke the wood and don't heat it up during sanding, it should be fine, regardless of thinness or thickness of the finished piece.

 

[Dvoigt]

Well I only nuked 1 blank, and it happened on several, but i will avoid doing that again.

I use the 5min epoxy from PSI, is that flexible enough or is there a more flexible one?

I don't create heat during sanding but probably do while drilling. I can try to go slower. Now I need to figure out how to disassemble some "classic roller balls" and some slimline pens.

 

[spiritwoodturner]

The 5 min. epoxy has little to no flex, to my knowledge. I think what he was talking about was probably the "rubberized" or flex CA, but I'm not a fan of that stuff for permanent bonding.

One other thing to consider. Are you getting anything, and I mean anything, inside the tubes while gluing up? Sounds kinda basic, but on occasion I'll get a little something in there, and I have my Dremel tool with a sanding sleeve ready to buff it out. Just a thought.

Where did you get this wood? How do you know it's dry? I'm with Marc, stabilizing won't help here. If it was snakewood, I'd tell you to get used to it, but I don't believe I've ever had that happen to bloodwood, and I've done bowls out of it and laid into it with my Sioux sander, and nary a single check, so my money's on something else.

Keep trying, I reckon.

Dale

 

[Dvoigt]

What about creating a chamfer on the inside of the tube to create a lead in a maybe reduce some of the force at the end of the tube. Is that a good idea? What would be the best way to create something like that?

 

[spiritwoodturner]

Buy a chamfer tool from AZ Silhouette. They're cheap. I use one on every pen, and it does help to make sure you don't get a piece started a tiny bit crooked. It don't take much!

Dale

P.S. Here's the link- http://www.arizonasilhouette.com/Barrel_Trimers.htm

 

[Darrin]

I have never had an issue with bloodwood. Ebony, yes but never bloodwood. I can only recommend low heat on the sanding and make sure its nice and dry. Chamfering the tube is a great idea as well. Good Luck!!

 

[marcruby]

Thickness won't make much difference. Bloodwood bowls don't crack because the whole piece is changing at the same rate. I use bloodwood for bowls and trim, it's weakest along the grain, although I wouldn't call it a weak wiid.

The problem really is a simple one of relieving the pressure from when the wood starts to shrink around the brass. I would think that, as long as the hole is a slightly loose fit you could get away with standard epoxy. If you Google 'flexible epoxy you will find a good selection. Sumo glue, which foams, might work. And CSUSA sells a flexible CA which might be worth trying.

 

[GBusardo]

I have turned a ton of bloodwood pen blanks and never had a problem. However, I have had one piece of larger stock that I was using to turn bottle stoppers and I had all kinds of problems, including cracking. Maybe you just got some bad stock?

 

[toolcrazy]

Drill a couple of pieces and let them set for a few days before gluing in the tube. Be sure to check the hole. You will probably need to re-drill them. If you do, you might want to let them set for a few more days. Keep testing them by inserting the brass tube. Your blanks may be a bit wet, still. And they are drying and cracking.

 

[Dvoigt]

Maybe you just got some bad stock?

No, becuase I've had it happen on 2 different lots from 2 different places. I'll take some of the tips that I've gotten from this post and see if i can't improve the condition.

Thanks!

 

[bitshird]

If you Nuke the wood, only use about 1/2 power and about 20 seconds, let the wood get cold between nuking.

 

[rick_lindsey]

My bloodwood pen cracked too, but then again it also slipped out of my fingers while buffing and got thrown rather hard into the lathe/table. :doh:

Lesson learned -- buff before assembly, while still on the mandrel! (though I was also getting a minor OOR issue even with a short mandrel, and at the headstock end to boot! As soon as I get my grubby fingers on a dead center I'm going to try turning between centers)

-Rick

 

[Dvoigt]

Well I've taken all of the advise from this post...

I made 2 pens with 7mm tubes. I drilled them slightly larger with a english (fraction) bit and glued them up, finished them up and assembled them. Then I kept my eyes on them for a few days. No cracks so I gave them to the person that ordered them.

The other day I made a pen with a 10mm tube. On Sunday cut and drilled the blood wood blank with a 10mm bit, then tried to reem out that 10mm hole with a round fle to try and open it up a bit. Then I glued it with a 2 part epoxy. On Monday I trimed it with my barrel trimmer and turned and assembled it, it went together nicely and looked good. I then look at it today (Tuesday) and there is a hairline crack a little over a half inch long coming up from the bottom and one less then a quarter inch coming down from the top of the same blank.

I'm at my wits end with this and don't know what else to do.

I keep all my stuff in my heated garage, but glued and it all in the house at room temperature, so I can't blame it on the cold... or can I?

Please help!

 

[marcruby]

Sometimes cracks are just gonna happen! Try letting the wood set for a day or so between drilling, gluing, turning, and assembly. That might help a bit. Of course there comes a point when you just give up on bloodwood.

One last thing - bloodwood lumber does develop very fine end checking. Is it possible that the wood is really already cracked when you start out?

Marc

 

[Dvoigt]

I closely inspect the wood when i use it because I've been having so many issues.

I don't want to call it quits with bloodwood! I love the look of the wood, and I don't seem to hear alot of other people having the same issues. So it isn't like we are dealing with Snakewood here.

I will get it eventually, it will just be a painful process apparently.

 

[Dvoigt]

If i can disassemble the pen, would filling the crack with CA and bloodwood dust make it ok? Of course I'll need to sand through all the CA that I put on as a finish.

I have never had luck taking pens apart, I order some punches from harbor frieght to help.

Thanks

 

[marcruby]

I'm not sure you need to take off all the old CA. I'd just fill the crack and use 400 sandpaper to rough the surface and put s few coats on and MM everything out. I'm about to do that to an Amboyna Statesman that, much to my surprise , cracked.

Marc

 

[GouletPens]

Yeeahhhh....bloodwood is kind of notorious for cracking, for all the reasons mentioned by everyone else. Do you rub the wood with acetone before applying the CA finish? It will help to get some of the oil off the surface for the CA to bond. I wonder if maybe soaking/dipping the pen before finishing would help the oily problem??? Never tried it. Just curious.

 

[workinforwood]

I use bloodwood a lot. It's the only wood I know of that is a good red color. I've carved dozens of flowers, made many a pen, and scrolled who knows what else with it and never had a crack develop. I think the wood you bought is wet.

 

[Darrin]

Brian..that Yeeeeeeaaah you did made me think of 'Office Space'. Sorry, to interrupt, I had a chuckle.