OD of a brass insert

spliced

spliced

AzB Silver Member
Silver Member
If the OD of a brass insert (7/16) is larger than that of a 3/8 pin, why is the 3/8 pin more likely to split the shaft when the cue bends at the joint? (edit: speaking about shafts without a collar)

Thanks
 
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I don't think a 3/8-10 is more likely to split a shaft. Repair I have done in this scenario are most commonly 7/16-14 threaded inserts. I rarely see shafts split from a 3/8-10. Somebody with more repair experience might chime in.
 
Sorry, forgot to mention I am speaking about shafts that do not have a collar. Assuming niether one has a shaft collar, Ive always heard that a 3/8 pin into wood threads is more likely to split than a 5/16 pin into a brass insert.

Bob frey, for instance, will not warranty one of his cues if you opt for a big pin with no collar. However, he will warranty one that has a brass insert but no collar.

What makes the brass insert less likely to split the shaft when it's diameter is larger, in turn having less wood around it for strength?

thanks
 
Maybe because a big pin is tighter fitting, stronger & less forgiving when flexed. A pin into insert isn't a very tight fit, plus a 5/16" pin is thin & more flexible than a 3/8" pin. Otherwise, I don't think an insert makes a shaft less vulnerable to cracking than a big pin. It just doesn't make sense.
 
The 3/8-10 is more likely to split the shaft out because it does not have the glue support that the brass insert has. The brass insert is normally epoxied in, so it gives more holing power by far than bare wood threads. The only thing keeping the shaft together with 3/8-10 tapped wood threads is the jont collar. I would never make another shaft without joint ring if using 3/8-10 wood threads. It is just begging for trouble.
 
I have had requests for all wood sneakies like this. What I do is bore a hole for the shaft, plug it with either purpleheart or bacote, and glue in the plug. Then I drill and tapped it for the 3/8-10 pin. It gave the shaft as Chris said , more strength due to the plug and glue. To this day , that cue is holding great. A local player has it so I see it often.
Just the way I compansate for the weak area in the shaft. Hope this helps,
Jim Lee
 
Leverage?

Is it because the 3/8" Pin is longer, 1 1/4" in most cases, and the Brass Insert is 7/8"?
 
Cue caps beat me to it. I agree with the depth of the hole in the shaft. Then adding the apoxy to hold the insert in would add some support.
 
So is adding a phenolic insert the best way to go on a big pin joint with no collar?
 
You are correct Sir

It's a big step forward.
The use of a phenolic insert will increase the strength in the joint area if and only if the the bonding mtrl. does it's job.
If the shaft splits now, it won't be the fault of the phenolic.
If the glue/epoxy fails in it's duties, you've actually created a weak point because in boring for the phenolic plug you have reduced the wall thickness of the shaft wood. The glue must do it's job.
Each component is reliant on the other.
The ideal bonding mtrl. would be one in which when lateral stress is applied to the cue, it will break elsewhere other than at the joint.
Dream-World stuff.
 
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