why don't joints "mushroom"?

[bruin70]

i heard long ago that the original purpose of a ferrule was to prevent the shaft tip from mushrooming. thinking about ferrules,,,what is the physics of this? why won't a shaft mushroom,,,it's not as if the WHOLE tip of the shaft is encased in some material the same way snooker cues are...snooker cues have that metal thing encasing it's tip , do they not? american cues aren't built that way.

at the joint, i pretty much heard the same thing,,,that a bare joint(like a sneaky pete) will mushroom, but i've never seen this in a sneaky pete. and even if that were the case, how would, say,,,a full ivory prevent this,,,or even a piloted. somewhere there, the cue's wood is cut and lays flush and there's always pressure on a stroke for the wood to find relief sideways. am i wrong?

just curious as to the physics of the thing.

 

[cueman]

Tips mushroom because they are softer material. Ferrules mushroom because the tip gets too low and spreads out and allows too much impact on the ferrule. Joints rarely mushroom as the striking force is absorbed that far back from the contact point. Plus there is nothing to spread out like the tip does.
Chris
www.cuesmith.com
www.internationalcuemakers.com

 

[cuetique]

The joint has two things going for it. First it's a much harder material than leather, and second, the adjoining faces of the joint don't accelerate in opposition to each other. The butt face and shaft face move in unison, never striking each other, and any force experienced on impact is also distributed over the entire surface area of the screw and shaft threading. If there is any impact between these faces, it would be comparable to two cars driving one behind the other at 30 mph, and the rear car giving the lead car a 1 mph "bump". The softer leather tip takes an impact comparable to a parked car getting hit by moving car at 60 mph -- it has a much tougher job.

 

[JoeyInCali]

My joints don't mushroom b/c I light them up before they have a chance to.
The ferrule is there to prevent the end of the shaft from mushrooming.
OF course a backer like melamine, ivor-x or carbon fiber can prevent that too.

 

[cuetique]

My joints don't mushroom b/c I light them up before they have a chance to.

I originally resisted the temptation, but you started it -- the real answer is: "Joints and mushrooms simply don't mix"

 

[Cornerman]

i heard long ago that the original purpose of a ferrule was to prevent the shaft tip from mushrooming. .

I doubt it. I have to believe that the original purpose of a ferrule was to fix a split or mushroomed tail.

The protection from splitting is the tip for the most part. Prior to tips, smacking the unprotected end of the mace tail repeadetly would mushroom and split the tail for sure. If you fixed it with a ferrule without a tip, I would guess it would end up cracking too unless they used metal (like brass) I suppose. Even then, brass wouldn't hold up too long either.

I often wonder if history has anything on this. Chalk pre-dates leather tips. I always naturally assumed that ferrules pre-dated tips as well, since it was already a known item in other wood and metal industries.

Fred

 

[bruin70]

My joints don't mushroom b/c I light them up before they have a chance to.
The ferrule is there to prevent the end of the shaft from mushrooming.
OF course a backer like melamine, ivor-x or carbon fiber can prevent that too.

i guess i stated my question wrong....if a ferrule is supposed to prevent mushrooming A, why doesn't the shaft do "B"...

 

[bruin70]

I often wonder if history has anything on this. Chalk pre-dates leather tips. I always naturally assumed that ferrules pre-dated tips as well, since it was already a known item in other wood and metal industries.

Fred

hmmmmmm. just wondering now,,,,,

if i'm playing with an unprotected cue and the tip either splits or mushrooms, i think my first thought would be to fix this, ie using a metal collar to cinch the mushroom. then maybe some time in the future, i would think about a preventitive measure like adding a tip.

 

[Chris' Cues]

I would have to say that the tennon inside the ferrule helps distribute the impact down through the center of the shaft, thus lessening the force applied to the outer part of the shaft. The tennon also helps hold the ferrule at a constant height in comparrison to the shaft, so it doesn't drive itself down the shaft which would cause it to mushroom.
This may or may not be correct, but it makes sense to me.
Chris

 

[Rangercap]

i guess i stated my question wrong....if a ferrule is supposed to prevent mushrooming A, why doesn't the shaft do "B"...

A ferrule is basically the same setup as a cue joint, but no screw, unless you build a cue with a threaded ferrule. You have two flat surfaces tied together with a shaft running through the center. If you fasten them so they cannot move, the impact of the force exerted on the top of the ferrule will get transferred evenly across the face of the shaft. the force will continue through the shaft, and to the joint, where it again will get transferred though the flat face. then on to the forearm/handle joint, and to your hand. We could talk about buzz rings, but that is another thread...

Your first picture is sort of correct, the top of the SHAFT will mushroom, since the wood fibers run parallel to the point of impact (if the wood fibers would happen to be perpendicular to the impact, it would splinter, like a baseball bat). But, the tip would mushroom first, since it is softer material. Its kind of like hitting a malleable iron pin with a hardened steel hammer. It will deform, or mushroom. The shaft may or may not mushroom, since the glue joint between the tip and the top of the shaft with act like a ferrule, holding the fibers together until the glue joint breaks. Then, mushrooms happen.

As for B, this would only happen if the glue joint between the ferrule and the tenon fails, and if the faces are not perfectly square. Then, a loose ferrule would act like a wedge, splitting the wood fibers. In the case of a capped ferrule, like you have shown, the picture you have is unlikely to happen. If the ferrule is not capped, and the glue joint fails, and there is a space anywhere in that ferrule tenon system, B would possibly occur.

If you made a shaft out of Balsa wood, B would probably not occur right away, as long as the tenon/ferrule is constructed correctly (the tenon would snap if you shot a hard shot with a lot of english due to the lateral force exerted on the wood fibres). I bet you could get a fair amount of play out of a basla shaft hitting only centerball hits.

Anyone built a balsa wood shaft? that would be cool to run through Bob Meucci's mystery machine....

I'm not a cumeaker, but I did stay at a Holiday Inn last night....

Brian

 

[JoeyInCali]

The ferrule cap, tenon threads and the shoulder of the ferrule absorbs most of the shock.
Actually a cap or a backer alone would be enough to prevent the shaft to mushroom. I have a 3mm thick hard backer on my shaft ( no ferrule ) and it's been enough.

 

[Cornerman]

hmmmmmm. just wondering now,,,,,

if i'm playing with an unprotected cue and the tip either splits or mushrooms, i think my first thought would be to fix this, ie using a metal collar to cinch the mushroom. then maybe some time in the future, i would think about a preventitive measure like adding a tip.

But remember that hitting the ball with the tail end wasn't as common of a shot compared to hitting it with the club end.

Fred

 

[Cornerman]

i guess i stated my question wrong....if a ferrule is supposed to prevent mushrooming A, why doesn't the shaft do "B"...

You've answered your question. Since the shaft doesn't do "B," then the premise that a ferrule is supposed to prevent mushrooming must be incorrect.

But, "A" doesn't happen either. Maybe that also solves your question.

Fred

 

[ShootingArts]

The cue joints can mushroom

The simple answer is joints and joint collars can mushroom if you have a crappy enough stick. The joint has a lot of material between it and the tip dampening and adsorbing impact and it also has a much larger area to spread the remaining forces over so if you have a decent joint it will never mushroom. However, very cheap sticks with plastic joints do mushroom mainly due to flex in the joint I believe.

I have a one in a million presentation cue by Budweiser I am working on right now, complete with the original vinyl case with only about an inch and a half round chunk of vinyl missing. I'm changing out the pin and joint collar on the butt and building an all new shaft to replace the deluxe ramin wood that came with it. I'm hoping that it will hit at least decently when I am done. I'll definitely look like Bubba come to town toting it!

Hu

PS Maybe this is a one of a million cue!