i might be reinventing the wheel but Im thinking of a way to straighten cues.
Visualize this :
take your cue and by rolling it on a flat surface you can mark the high side of the bend and where the most serious part of the bend is. one way to examine it is to roll it on a flat surface with a flashlight placed behind the cue on the table. look for the light gap. the pool table is the obvious flat surface, often I will use a piece of thick glass, as glass is generally fairly flat. accurate tables for machinists are often precision ground slate.
mark the high spot of the bend with a bit of tape. also mark the portions where the bend diminishes.
I could take a hunk of metal pipe , about 2" diameter and cut a slot in it lengthwise with about a 3/4 gap. each end has a removable plastic bushing to support the two ends of the cue. the gap is just so you can see inside.
the walls of the pipe are threaded in different locations, 1/4 inch plastic bolts are inserted. with the highest spot of the bend marked then the cue is situated so one of those bolts can bear down a bit upon the bend, effectively forcing it to straighten, with a bit extra , knowing there will be springback. you will probably have several screws involved applying pressure at the appropriate points.
for the sake of simple explanation just think if two screws bearing down on either end of the bent portion and one screw opposing them , forcing that bent portion to move a small amount.
It may be necessary to apply pressure near to the bend using the screws as you can assume the bend is going to be in certain locations , what you want is to apply some opposing force near the bends and support it accordingly. The " pipe" jig may be made smaller if you were just working on the shaft. One could drill and thread in as many places as they liked. the cue can be padded to protect it from damage from the plastic screws.
Some mild humidity can be used, too much humidity may affect finish or bonding but perhaps some temporary humidity increase is OK. It will speed the process, but it may work dry, just take more time.. the cue is then stored a while and released, then re-examined.
this is a trial and error method, there is no damage to the cue or it's finish, but time is allowed for the bend to move more towards straight. You can expect it will take a few tries and some time but I believe most cues can be made straighter this way.
wood does have a tendency to go "where it wants" as the natural stresses and age take place. If a cue is made quickly without proper time to find it's natural position then it may warp simply because the natural stresses in the wood are causing wood movement. in this case it may want to return. If the cue is a well made one but was stored leaning against a wall , then what you are doing is reversing the same pressure only with a bit more force to speed the process.
certain species have better tendencies to stay straight. trees that grew in close proximity to one another grow very slowly , growth rings are very close together then, sections of the tree not near branches will usually have straighter grain different species have different characteristics. often more beautiful wood is beautiful because of figurative grain patterns and this can result in "ribbon" or "chatoyance" - these interesting grain patterns also mean warpage. - best saved for the Butt end, the shaft being maple or ash maybe hickory, hardwoods. Maple can be in some cases quite difficult as it can have a lot of internal stress. Cuemakers know what thye are looking for and why.
Id like to try this on a few of my junk cues. It might help save some that are worthy of a bit of time and patience. It's not rocket science and I assume others have tried similar approaches.
I sometimes need to straighten bent iron shafts for machinery and will use a similar process. it takes some patience and a dial indicator can be used as well as this little trick. if you roll a shaft and hold a felt pen near it, trying to barely touch it, then the pen will tend to mark the higher side. a few tries at this will show the high spot. some of your marks may differ, but you are looking for an average where the lines appear more or darker. Ill often us it on a lathe rather than reaching for a micrometer just to help chuck up a shaft quickly and see it set in the chuck fairly concentrically before turning, Ill simply turn the lathe on and hold a pen near the rotating piece, then very slowly move a felt in towards it, the high spots touch first and the high spot is immediately evident. Thats just a quick trick. The more accurate way is to use a dial indicator and measure the run-out. a 4 jaw chuck can be adjusted , a 3 jaw chuck finds it's center by its nature. the 4 Jaw is more accurate because it can be dialed in.
with iron , time won't help much , what I will do is put shims and apply blows to very certain areas causing bend in a way that straightens the shaft, Its still a process of trial and error , lots of checking, some blows do nthing too much and you are running back and forth going crazy what we want is very small adjustments in the correct direction, eventually reaching a state of trueness that is acceptable, this is never perfection. Its what is acceptable. Perfect is the same as infinity. that should not be the goal. Its about getting into a range of acceptable tolerance or reaching a point where more time equates to very little difference, or a state of diminishing results.
Id never expect an immediate result.
Wood has different characteristics, we wouldnt use hammer blows, but time and pressure instead.
Cue lathes are special machines that I know little about, I'm more familiar with wood and metal lathes. I'd like to learn more..
If a long shaft is turned on a metal lathe there will be deflection in the middle. This is unwanted as it causes the ends to be smaller than the middle ( ignoring taper) a steady-rest can add support to help, I assume a lathe built for turning cues may have more than one steady rest and perhaps things like a sanding attachment. It also needs to be longer and to turn a taper the operator may offset the center, probably on the end opposite the chuck ( or collet). One way to reduce the pressure of the cutter is to use a toolpost grinder so it can cut without applying a lot of side load. similarly a sander or router may be used to reduce the load of the cutting tool. Perhaps cues can be given a fine cut or sanded to restore trueness , this is a different process. I do not think applying a controlled force to a cue is going to fix problems with threaded attachments. those are deeper issues.
The iron pipe idea is pretty straightforward by comparison to turning cues. you are simply storing the cue with a calculated pressure applied to move it slowly in the correct direction over time.
Straight is really much like an infinite measurement, even a high end cue is sure to be bent if you have the means to measure accurately enough. If you think your cue is straight, try rolling it on a truly flat and true surface with no felt with a bright light on the table behind it , look under the cue at the sliver of light.
I bet you will see by the gap of light that you can detect bend and that's just natural that there will be some. What is acceptable will vary between individuals and manufacturers.
I often hear of people advertising or saying a cue is straight, or dead straight.. (whats the difference? ) What they are really saying , in my mind, is it is straight enough to be acceptable to them or to the means they have used to detect bend. since this varies it can cause issues, you said this thing was straight !
Most will show some variation just by rolling them on a table and looking carefully. I'm sure its possible to quantify the amount of bend and the tolerance.
how much bend affects play I don't know. I think many of us have had the situation where they are playing someone who is a better shot and knows they are using a bent cue.
It's easily proven The accuracy has a lot more to do with the cue pusher than the cue. I think that knowing your cue is bent could play upon confidence and that may affect play.
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