Problems with Red Coolibah Burl

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keithy

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Joined
May 5, 2015
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52
Location
winston salem
I bought 2 Red Coolibah burl blanks from West Penn Hardwoods in their recent opening sale. Along with a heap of other burls and timber in assorted sizes. Cut and drilled these ready to turn. Glued in the tubes (two with CA, two with 5 minute epoxy)

All four exploded while turning beyond salvage. I had turned them round with a 3/8 gouge and was taking them down towards the bushings with my carbide tool (just sharpened) The last two I was taking very fine cuts and stoping every few cuts to check for flaws cracks and checks. Nothing visible at any point before the failure.

I like this wood very much and want to make a couple of pens for presentation to my aussie mates. How can I stabalise it enough to finish.

Keith
 
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You could also try pouring some thin CA into the drilled hole of the blank before inserting the brass tube. Make sure you plug the bottom hole and rotate it around to soak all of the inside of the blank. That way when you get close on the final turning that part is more stable. You may need to sand the inside if the brass tube wont fit, or re-drill the blank. Also, adding Thin CA as you turn will help hold things together.
 
Standard questions:
1. Did the wood come off the tube leaving bare metal? Did the brass look clean where it shattered or were there little bits of timber stuck to it?
2. Did you sand and/or scuff the tubes before gluing?
3. Were you working from the end to center or center to end?
4. Turning one barrel at a time TBC or on a mandrel and two at a time?
5. How did you drill and what did you use to prevent internal stresses while drilling?
 
1) the wood came off leaving bare metal with little bits of timber stuck to it.
2) the tube was scruffed before glueing
3) turned end to center
4 turned on a mandrel with mandrel saver. first two were two up the last two were one at a time.
5) two were drilled on lathe and two with drill press and vice. all were pecked i.e. drill 1/4 inch and back out repeat until through.
 
Here's a test. Use just your hands, and not a lathe. Take a new #2 wood pencil and try to sharpen a point on it with a freshly sharpened carbide scraper. Now do the same thing with a freshly honed skew with it's shearing cut. Which one works the best? Same result with a wood pen blank.
 
Best insurance against this is stabilizing. I would not attempt to turn any burl or softer wood (i.e. spalted) without stabilizing it first. You can still have a blowup problem but the chances are reduced tremendously. Burl is expensive, stabilizing is cheap insurance. Soaking in CA as you go is better than nothing and works well for some people. I prefer vacuum with Cactus Juice Resin to stabilize. (This is an endorsement, not a commercial). You should be able to get it done for $2 or $3 a blank, and cheaper if you do it yourself once setup is paid for.
 
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