Mystery Diagnosis

Bumlak

Bumlak

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So I got a repair back today and I wanted some input. A little background: Porper ferrule threaded and capped installed in the usual manner using a compression die. Please note that the dark line running down the shaft from the crack is a sugar mark.

The ferrule and tip appear to be in good shape. I've installed lots of these ferrules and never had an issue. I'm leaning towards either hydraulic pressure (which I wouldn't give a high confidence to because of the glue relief hole) or maybe just a mismeasure in my epoxy (BSI 5m like I've used for years.)

Thoughts??
 
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cueman

cueman

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If ferrules crack from the bottom side where it bottoms out on the shaft, it is usually because there was unwanted pressure at the end of the ferrule. This can be from the threads not going all the way to the end of the wood tenon and no relief shoulder being bored into ferrule. Or the relief or alignment shoulder inside the ferrule was too tight or slightly off center to the internal threads. Either way it can create pressure and cause the ferrule to crack.
 
Bumlak

Bumlak

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cueman said:
If ferrules crack from the bottom side where it bottoms out on the shaft, it is usually because there was unwanted pressure at the end of the ferrule. This can be from the threads not going all the way to the end of the wood tenon and no relief shoulder being bored into ferrule. Or the relief or alignment shoulder inside the ferrule was too tight or slightly off center to the internal threads. Either way it can create pressure and cause the ferrule to crack.
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Chris,

Would running a 5/16-18" tap into the ferrule help at all just to clean up the internal threads? Interestingly, I don't remember this one going on any harder than any others but I do so many I could be forgetting. Looked like the threads went all the way down but I think I may use the back end of a utility knife and pressure in a groove or two from now on.
 
JoeyInCali

JoeyInCali

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I don't know why you would need pressure groove or two.
Your tenon size is less than .300 for that tenon die to work.
The tapped hole is 5/16 18. Plenty of room for the epoxy to top out.
 
Bumlak

Bumlak

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JoeyInCali said:
I don't know why you would need pressure groove or two.
Your tenon size is less than .300 for that tenon die to work.
The tapped hole is 5/16 18. Plenty of room for the epoxy to top out.
Click to expand...

I think I was thinking the wrong side of the ferrule when I posted that Joey. Thinking about it now, I believe the relief alignment shoulder Chris is referring to is the section just below the glue relief hole. I was just thinking in reverse.
 
BarenbruggeCues

BarenbruggeCues

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I've installed lots of these ferrules and never had an issue.
Click to expand...

Or it could have just simply been a bad ferrule to begin with. Happens sometimes...replace and stick it in your "got my eye on ya" file.
 
cueman

cueman

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Bumlak said:
Chris,

Would running a 5/16-18" tap into the ferrule help at all just to clean up the internal threads? Interestingly, I don't remember this one going on any harder than any others but I do so many I could be forgetting. Looked like the threads went all the way down but I think I may use the back end of a utility knife and pressure in a groove or two from now on.
Click to expand...
Bore or drill a full 5/16" or larger into the ferrule for 1/16 to 1/8" and leave a matching shoulder on the bottom of the tenon and that will eliminate those bottom threads from acting like a splitting maul. The other option is under cut the tenon for the last couple of threads but that just creates a weak point in the tenon.
 
cueman

cueman

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Bumlak said:
I think I was thinking the wrong side of the ferrule when I posted that Joey. Thinking about it now, I believe the relief alignment shoulder Chris is referring to is the section just below the glue relief hole. I was just thinking in reverse.
Click to expand...

No the alignment shoulder is at the bottom of the tenon.
 
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