Ferrules
Different styles & construction techniques

There are several styles of ferrules in use today.  The common variables are:

The diameter of the tenon
Whether the tenon is threaded or not
Whether the ferrule is capped or not

  The simplest option is a sleeve type ferrule that slips over a tenon and is retained by wood glue or epoxy.  The size of the tenon can vary for a few reasons.  Usually it will depend on the strength of the ferrule material used but some cuemakers feel a larger tenon gives a better hit since you have a simpler, purer connection.  You're making a better, more direct contact with the shaft, so to speak.  Warning: many of the cheap (and not so cheap) imports use a sleeve type ferrule made of an "economical polymer material" that doesn't bond well with any glues.  They use ribbing on the inside of the ferrule to provide a mechanical bond to the tenon.  It is sometimes difficult to get tips to adhere to these cues.  The only foolproof solution is to replace the ferrule with something worthwhile.

Then, there are those who feel that the tenon should be threaded in order to incorporate a mechanical bond to help retain the ferrule while at the same time, providing additional surface area for your glue.  The standard threaded ferrules commercially available are tapped 5/16-18.  Some feel this size "thins" the tenon too much, weakening it at the base of the tenon.  Others choose to use different thread sizes & machine their ferrules to their own specs.  Another option is to add a locating diameter at the base of the tenon.  This will serve the dual purpose of adding strength while keeping the ferrule accurately centered on the tenon.  

I feel I have to comment on the "compression dies" being sold to make tenon threading easier.  Personally, I don't like them.  While they give the illusion of a thread, you actually have less than 40% of a full thread.  Think about it - the tap drill size for the ferrule is .257 while the tenon diameter prior to running the die over it is .280.  That means you're forming a thread just over .011" high per side.  That's your thread??  There's enough there to allow you to thread on the ferrule & you can even tighten it up against the shoulder a bit.  But you still have a tremendous volume of empty space that must be filled with glue.  And this sloppy, glue-filled reservoir has to repeatedly absorb the most brutal shocks your cue will experience.  That can't be the best way to do this.  'Nuff said. 

Both styles described above can be capped or not.  It might depend on the material being used or simply the preference of the cuemaker.  On one hand, a capped ferrule is unquestionably stronger & provides a consistent surface upon which to glue your tip but, on the other hand, it introduces the opportunity for air pockets which may affect the sound of the hit (although it won't affect how it plays).  The uncapped ferrule offers the most direct connection to the shaft but it is more likely to crack or split than a capped ferrule.  This is where the tenon diameter comes into play, forcing a compromise between tenon diameter (solid hit) vs. ferrule wall thickness (resistance to cracking).  But then, maybe if it were threaded, the additional glue surface will prevent it from cracking. But then...and on and on.  

Now you can see why there is no consensus as to what is the best design.  As a result, I am constantly trying new materials as they become available & as others become obsolete.  Some play well but get dirty easily.  Some are too hard and squirt more than others.  Some are too soft - they play well but scratch, dent and crack too easily.  Some don't like wood glue.  Etc, etc.

A new ferrule material.  

Remember the old yellow Micarta that was in favor more than 20 yrs ago? (see additional info below)  An enterprising new cuemaker, Mason Houghland, has commissioned the production of a very similar material, hoping to bring back its desirable playing characteristics while minimizing its squirt and hazardous materials.  The company that bought Westinghouse and owns the Micarta name makes this new material.  Mason calls it his linen based Micarta and claims that is stronger than LBM and slightly lighter in weight.  The tubing is rolled rather than sheet and is free of pits & debris.  I recently acquired some & will be offering this material as an option on my own cues.  Initial trials show it to be easy to machine though somewhat abrasive, generating some heat when tapping.  Coolant is recommended & you might be required to re-tap the threads.  Appearance is nice & playability is at least on a par with anything out there.  Time will tell if the material remains resistant to chalk dust.  I will update this in a few weeks (today is 5/29/09) after putting some miles on this new material.  Update (7/5/09): material stays clean & plays pretty nice.  Softer than the old stuff but gives a nice, solid hit.  I like it.

Installation Procedure for a Threaded Through Ferrule

           
Click on the thumbnails for more details.
The ferrule installed here is Mason's Micarta Tube with a 3/8-24 thread.  This is only one method of installing a ferrule but it incorporates some of the best ideas.  A register diameter is nice for accurately locating the ferrule concentric to the tenon while the threads provide a solid mechanical bond.  The cross section view shows how nicely  everything fits.  The fine threads fill the tapped hole almost perfectly for a solid connection.  I recommend the use of a 1/4" shank cutting tool to reduce cutter deflection. 
It definitely won't look like this if you use a compression die.

 See HERE for my method of threading a tenon.
Note that the video shows 3/8-16 threads being cut while the above pictures show 3/8-24 threads.
After experimenting with 5/16-18, 3/8-16 and 3/8-24, I find I prefer the 3/8-24 threads.  The tenon remaining is about as strong as you can get while still using a ferrule.  It is significantly stronger than a 5/16 diameter tenon with the added benefit that it is not excessively undercut by a coarse thread.  Now I'm sure someone will point out that 5/16 tenons have been used for years without problems but I beg to differ about the "without problems" portion of that statement.  Granted they work well in general but why not improve something if you can? 
As long as the ferrule is strong enough, leave as much of the original shaft in place to provide the maximum in strength & "feel". 
It's just common sense.

In response to a few inquiries, here are some details about cutting a 5/16-18 tenon.  I turn the OD to .3125 with a .190/.200 long register that is slightly larger at .320 diameter.  I touch up on the .3125 diameter with my threading tool & plunge to a final depth of .040/.042.  The depth can vary because some ferrule materials don't tap as cleanly as others.  I don't take it all in one cut.  I usually take a pass at .030 deep, a second cut at .038 and a final pass at .040.  A trial fit of the ferrule lets me know if another pass at .042 is required.  The picture above shows the finished tenon as it comes out of the lathe.  Usually I hit it with a toothbrush while still in the lathe to remove the fuzzies but I forgot in my haste to get these pictures up.  Again, let me emphasize the importance of starting with a full diameter.  The whole concept of cutting your threads with live tooling is to get a full, perfect thread form.  Why defeat the purpose by starting out with your major diameter undersize?

Another sequence showing the installation of a short ferrule on a 3/8-24 tenon.  This tenon also has an 1/8" locating register at the shoulder.

This is an extreme example of the difference between a full thread form & the shortcuts some are willing to take.  The tenon on the bottom was made by a fairly well known & respected cuemaker.  He relies on the ferrule itself to cut the threads on the tenon.  Considering that the normal tap drill is .257 diameter & his tenon was .272 diameter, that leaves a total thread depth of .0075".  Not much of a thread.  And not surprisingly, the ferrule came loose in a fairly short time & required the installation of a new maple dowel to correct the problem.

And now, a word about Micarta...
A long time ago, in a world where asbestos wasn't a dirty word, there existed an insulator made by Westinghouse called Micarta.  It was (depending on who you talk to) either an asbestos based or a paper based phenolic resin that was used in the electrical industry.  Some cuemakers found that the reinforced product withstood the rigors of a game of pool & used it to make ferrules.  It was a putrid color but it was strong and it was cheap.  Then along came the EPA and Micarta, as the pool world knew it, disappeared.  Many years later, as aging pool players reminisced, memories of sharper skills, dancing cue balls & seldom missed balls caused these former world beaters to wonder why they could no longer play like they did in days of yore.  Since the fault couldn't possibly lie in their own abilities, it had to be the equipment they were using.  But what was different?  Of course!  It had to be the Micarta that was no longer available.  If only they had that old Micarta, they could once again be the players that resided in their memories.

And so, despite the plethora of new materials produced today, there is still the quest for that which was once, but is no longer, available.  The almost mystical qualities attributed to the Micarta of days passed has given rise to an almost cult-like following of this magical material.  And fortunately, thanks to the miracle of eBay, almost anyone can now own this Holy Grail of ferrules.  That is...if you're rich.  It is pretty pricey, of course.  And it might not really resemble the material the Micarta of the past.  But it WAS made in many different formulations so if it's yellow & reinforced, it can probably safely be called Micarta.  I guess. 

Below is a picture of a material, commonly sold as the original Micarta, that is obviously linen based.  Below it is an old Scruggs ferrule from 1985 that is definitely the original Micarta and just as definitely not linen based.  And on the bottom is Mason's Micarta.  Again, a linen based material.  Now let me be clear here: all 3 of these materials hit very nicely.  But they are obviously different materials.  And since I obviously have nothing better to do, I feel an obligation to present this information to the general public.  I have no axe to grind nor do I have any conflict of interest but I am asked about the differences in these materials almost weekly.  This picture shows the differences very clearly.  If you MUST have the Micarta look, the material on the top is closest.  If you just want a strong, solid hitting material that sort of resembles the original Micarta, the material on the bottom is a much cheaper alternative.

Another thing to consider...
is ferrule weight as it relates to a shaft's tendency to squirt.
Maple is given a value of "1" and this chart shows how a few common ferrule materials compare.
Remember, a higher number (heavier material) will have a tendency squirt more than a lower number (lighter weight).

Maple was given the reference weight of 1.  A material with a relative weight of 2 would be exactly twice as heavy as maple.
The sample of maple I used was chosen at random.  I really don't know if it was lighter or heavier than normal so this whole chart might be a waste of time.

The weight of maple shafts can vary considerably.  Most people prefer a shaft with high grain count & dense wood - usually heavier, rather than lighter.  This might not be the best choice to make if low squirt is your priority.  The dense shaft might sound & feel better but...

Don't you just love it when something new comes along to confuse you?

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