Potentially deadly platter

[john lucas]

I thought I would pass this on. I was cutting out platter blanks this morning from dry wood. This one looked sound until you inspected it extremely close. In fact I would not have found it had I not done my usual test. As I cut off the corners I flex them or tap them on the workbench corner. If one breaks I suspect there could be a problem. On this piece 2 broke almost exactly opposite each other. I inspected the blank very very closely and could barely see the crack on one side. I traced the grain across and could see it on the other side as well. I could not see it on the back or the freshly cut edges. This was a heavy wood and that is about 1/3 or more of the piece that would have flown off once I cut started thinning it out. That would have been very dangerous.
When I cut green wood I typically cut 3 to 6" off the end to get rid of end grain checks. To make sure I make another cut about 3/4" thick and bang this on the corner of my cutting stand. if it breaks I off another 3/4" until I'm sure it's sound. Chainsaw cuts can often mast checks that are still in the log so look very carefully or do the test I do. The very first line of defense for safe turning is starting with sound wood.
I'll be turning ornament finials today so no danger other than possibly a paper cut from the sharp edge of a freshly cut edge or sticking my fingers into the chuck.

 

[John Teichert]

Wow John, good catch.

I started turning a oak blank yesterday that had wildly figured grain around a limb. Although both ends of the blank appeared to have solid wood, as I trimmed the end that would be the mouth of a vessel with it mounted in a chuck, and working on the tailstock end, I was suddenly turning a bit of open air. Since I was still in the roughing out stage, it was being turned slowly (300/400 RPM). Turned out portions of the center was very punky wood / open air. I was very glad I started on it cautiously and with small "bites". About 1/8th of the side is disintegrating. It is interesting, but I don't know how much further I will try to coax it into being other than a burn pile candidate.

 

[Ian Thorn]

That's a good post John and something for all to be aware of I do the same test as you it could save a trip to A&E.

Ian

 

[Tom Coghill]

Great teaching lesson. 🙂

Now tell me honestly, are you tempted to CA that crack closed and see what you get??😱

 

[john lucas]

Absolutely not. CA is brittle. If you got a catch or even took a very large cut you could still have it blow up. I have on rare occasions broken the piece in half (since it's already about to go anyway) and then glued it back together with colored epoxy. Even then I don't totally trust the epoxy (even though I've never had one break). when I turn something that's been glued together like that I never get in the line of fire and turn at slower speeds. I know it's risky but I do all I can to reduce the risk by using sharp tools, taking light cuts, turning slower and of course wearing protective gear and staying out of the line of fire.

 

[MichaelMouse]

The glue, as they always remind us, is stronger than the wood. When a piece splits off on its own, it's got a lot of weak short fibers bent and sticking up on the surface, so if you're going to reattach, run a wire brush on both sides prior to the refit. If the crack is largely intact, tape one side and wick in water-thin CA. There will still be a lot of cross-crack fibers to help.

They also make a flexible CA, though , once again, more likely the wood will split than the adhesive. No glue or wood can survive poor technique, so always cut at arm's length.

 

[hockenbery]

Absolutely not. CA is brittle..

Like john, I never depend on CA to provide a structural bond.

I often use it for bonding bowls to a glue block. When the Bowl is finished a chisel in the glue joint breaks the glue.
I can clean the glue from the glue block with a gouge and reuse it literally hundreds of times.
Probably the most effective way to bond wet blanks to a glue block.

CA is one glue that is not stronger than the wood!

A catch would probably break the glue joint as well.

 

[MichaelMouse]

CA is one glue that is not stronger than the wood!

A catch would probably break the glue joint as well.

Sure. It lacks shear strength, but then again, if it's being used to close a split along the grain of the wood, even that is moot. The wood will split along the grain more readily than the glue joint. I rely on this phenomenon every year when I start hitting the ends of logs with a maul.

Too many present have used it too many times in too many ways to believe it presents a danger.

Now if you're going to heat or soak....

 

[Bill Boehme]

The glue, as they always remind us, is stronger than the wood....

The "they" in this instance are the marketers. While it is not a false statement, that may not be the whole story. A chain is only as strong as its weakest link.

Something caused the wood to fail. It is unlikely that the failure was only one or two cell layers thick which in some cases suggests that we have a very strong glue line holding together two pieces of weak wood.

 

[John Torchick]

sticking my fingers into the chuck

That could ruin your whole day! I did leave the chuck key in the Jacobs chuck but noticed it before it started the lathe. Got to think of a way to prevent that from happening again.
Thanks for the tip. It could save someone a lot of pain and discomfort by having a plate or bowl fly apart.