Curiosity question - lathe alignment testing

kevoka

AzB Silver Member
Silver Member
I have no experience building cues but am wondering how often do low production, or custom cue makers have to test, and/or re-calibrate their lathes and taper machines to ensure they are still within to their specifications?
 

Ron Padilla

AzB Silver Member
Silver Member
your post hasn't been up long so you might get a few answers, but I will tell you what I know, as for testing you can do it as often as you want all there is to it is making sure that your tail stock and jaws line up correctly and that is done a few different way? you place a bar that is know to be straight and held between the tail stock and jaws that hold live centers and then checked with a gauge and have zero movement on the gauge.
Others may add more or say I am all wrong and give a different answer or one that ex[plains it differently, you can also find answers on utube!
 

Dave38

theemperorhasnoclotheson
Silver Member
I have no experience building cues but am wondering how often do low production, or custom cue makers have to test, and/or re-calibrate their lathes and taper machines to ensure they are still within to their specifications?

I check it on every pass, as I measure both ends and do the math each time. Maybe that's over doing it, but it's not a bad habit to check each time. Even with a very sturdy bench, depending on temp and humidity, things can change ever so slightly.
Dave
 

kevoka

AzB Silver Member
Silver Member
your post hasn't been up long so you might get a few answers, but I will tell you what I know, as for testing you can do it as often as you want all there is to it is making sure that your tail stock and jaws line up correctly and that is done a few different way? you place a bar that is know to be straight and held between the tail stock and jaws that hold live centers and then checked with a gauge and have zero movement on the gauge.
Others may add more or say I am all wrong and give a different answer or one that ex[plains it differently, you can also find answers on utube!

Thank you for the reply. I am aware of a couple of the various methods, but was interested in whether trust in the machine setup lasted longer than just one setup.

Eg. if the tailstock gets moved on the bed for a different operation - say from turning to a drilling operation - do you run this test again? This means you have to have several fixed length test bars.
 

kevoka

AzB Silver Member
Silver Member
your post hasn't been up long so you might get a few answers, but I will tell you what I know, as for testing you can do it as often as you want all there is to it is making sure that your tail stock and jaws line up correctly and that is done a few different way? you place a bar that is know to be straight and held between the tail stock and jaws that hold live centers and then checked with a gauge and have zero movement on the gauge.
Others may add more or say I am all wrong and give a different answer or one that ex[plains it differently, you can also find answers on utube!

Thank you for the reply. I am aware of a couple of the various methods, but was interested in whether trust in the machine setup lasted longer than just one setup.

Eg. if the tailstock gets moved on the bed for a different operation - say from turning to a drilling operation - do you run this test again? This means you have to have several fixed length test bars.
 

JoeyInCali

Maker of Joey Bautista Cues
Silver Member
[Buy a 30" Steel rod.
Epoxy phenolic discs on the ends.
Center hole them after epoxy dries.
You can use that to dial indicate.
You cab use that to indicate your rear chuck.
 

kevoka

AzB Silver Member
Silver Member
[Buy a 30" Steel rod.
Epoxy phenolic discs on the ends.
Center hole them after epoxy dries.
You can use that to dial indicate.
You cab use that to indicate your rear chuck.

How often do you run the dial indicate test? After any configuration change (like moving the tail stock)?
 

Ssonerai

AzB Silver Member
Silver Member
On a metal lathe with V- or dovetail- ways:

If the TS is moved sideways by means of the off-set feature, say to cut a long straight taper without a taper bar, you will have to re-indicate when you want it back on center.
Also, this taper will vary (with same offset) at any different distance from spindle.

If the TS is only moved back and forth along the ways for different lengths, and if it was centered "recently", there is no need to to re-indicate unless you had a wreck or someone bumped it with the forklift or something.

Over time, TS's wear from being slid back and forth, and the nose starts to droop. This will gradually introduce a taper. It can be compensated by the taper bar alignment. The ways wear where the carriage moves the most. etc, etc. Eventually the lathe is worn out and you have to get the ways re-ground and rescrape all the components and fit them back on and start over. In between you check periodically, and fudge where necessary. But just moving the TS back and forth, nothing changes for months or sometimes years, if the lathe is clean and maintained (oiled, etc).

Ideally test bars should be spun in freshly turned or ground dead centers, not live centers. Lathes are built accurately enough that the live center bearing error can be a factor indicating critical work. But for cues it won't matter, so long as the person doing it is aware that there could be an error potential & factors that in if something is anomalous.

smt
 
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Ron Padilla

AzB Silver Member
Silver Member
If a person has off set the tail stock and not trusting marks that are on the tail stock then yes it would be wise to check with what ever method a person has settled on, it should not take very long. Like some makers would use a dial indicator all the time to check run out so that every build is accurate!
 

Kim Bye

AzB Silver Member
Silver Member
You get used to doing measurmets, it's part of the job. For alignment I have a MT3 test bar and the Edge tailstock alignment test bar, unless you do alot of off center drilling, the tailstock alignment stays true, atleast on bigger metal lathes.
 
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scdiveteam

Rick Geschrey
Silver Member
Hi,

I use a Prescision Thomson Rod. By using this calibration tool as a datum, you can check the alignment between the chuck and your tail stock from 0" to 30" along the bed. It is important because as you move from 0 to 30 inches, any alighnment error is amplified the further you move away from the the chuck. This is very important when cutting a wrap groove step between centers.

My Thomson rod is straight within .0002 over the 30" length and is case hardened. I use a precision indicator graduated at .0005 increments. It is always a good idea to pre load your indicator to .007 before zeroing and reading along the rod. One should turn the chuck 360 degrees by hand at each location you check along the 0 to 30" distance.

You can adjust your tail stock Y axis with the adjustment feature. You can also adjust vertically by using precision shims.

These rods don't come with 60 degree centers so using your lathe to install centers does not make sense. I used my Hardinge Collet Chuck Tool Room lathe to install the centers. That lathe has brand new head stock bearings and the TRO is Zero. If you dont have this type of precision in you shop seek out a precision machine shop. The centering operation only takes a minute or 2 to perform and the price of a pizza should get the job done.

If you have a 6 jaw set thru Chuck, you should check and adjust your chuck TRO and also make sure your lathe is level on the X and Y axis also.

I check my lathe about once per month.

I just moved my shop equipment from Palatine to my new location in Las Vegas. I just adjusted and leveled my lathe it needed calibration from the trip over the Rockies. I will monitor it weekly to make sure it dose not settle and get out of wack.

JMO,

Rick
 
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Ssonerai

AzB Silver Member
Silver Member
If you have a 6 jaw set thru Chuck, you should check and adjust your chuck TRO and also make sure your lathe is level on the X and Y axis also

Or go all oldschool and do it with the 4 jaw. :)

I'd trust a 3J Adjustru, or a 4jaw with decent jaws over a collet for this op. Even Hardinge "extra precision" series collets can have some run-out when mated with a given spindle, if the units are 50 millionths or even a couple tenths.

IOW, if using extra precision collets, the bar should still be indicated and maybe bumped around to settle it.

Either way, the other end of the bar (outboard of the chuck) ought to be indicated to verify it is not hula-ing.

An even better method is to use a 4jaw, and a (solid finger, not roller) steady rest; both set up with all good practice. The steady forces the bar to rotate concentric with itself at the end that is drilled regardless any slight taper in the set-up, the 4J can dial it in at the other end until the needle does not flicker; utilizing both resources eliminates both taper and eccentricity from the equation..

smt, just up the hill overlooking the (former? :( ) Hardinge plants
 

BarenbruggeCues

Unregistered User
Silver Member
I have no experience building cues but am wondering how often do low production, or custom cue makers have to test, and/or re-calibrate their lathes and taper machines to ensure they are still within to their specifications?

The simple answer is measuring.
If you want to check your tail stock alignment at any given point on the bed, just take a short pass on a spinning piece of wood between centers and measure both ends.
Make necessary adjustments.

One of the most important aspects before you will have accurate readings on any lathe is the machine MUST be leveled with a machine level in all directions.
A carpenters level may get you close but probably will not get the job done to my liking.
Even on the large cast bed machines the bed can flex if it is out of level and throw things off. I can only imagine on the smaller cue building machines how easily this can happen.
After initial set up on a machine I check the levelness 2-3 times in the first month and maybe a couple times a year after. It takes about 60 seconds of my time to check and a little longer if adjustments are needed.
 

kevoka

AzB Silver Member
Silver Member
I really appreciate all the responses. I am not intending to take up cue making, but have been fascinated by the operations and precision that cue making requires, especially given the nature of the material.

My question was generated from having spoken to metal and plastic mold machinists who have varying degrees of precision requirements and how often they test their machine alignments. They are using higher end equipment.

Given the cue making specific equipment out there, I would envision the testing frequency would need to be more just due to nature of the equipment and the platform.
 

JoeyInCali

Maker of Joey Bautista Cues
Silver Member
Or go all oldschool and do it with the 4 jaw. :)

I'd trust a 3J Adjustru, or a 4jaw with decent jaws over a collet for this op. Even Hardinge "extra precision" series collets can have some run-out when mated with a given spindle, if the units are 50 millionths or even a couple tenths.

IOW, if using extra precision collets, the bar should still be indicated and maybe bumped around to settle it.

Either way, the other end of the bar (outboard of the chuck) ought to be indicated to verify it is not hula-ing.

An even better method is to use a 4jaw, and a (solid finger, not roller) steady rest; both set up with all good practice. The steady forces the bar to rotate concentric with itself at the end that is drilled regardless any slight taper in the set-up, the 4J can dial it in at the other end until the needle does not flicker; utilizing both resources eliminates both taper and eccentricity from the equation..

smt, just up the hill overlooking the (former? :( ) Hardinge plants

If I had to use a 4-jaw in every operation, I'd go nuts after one day.
There are very few operations in cue making that might require a 4-jaw.
 

conetip

AzB Silver Member
Silver Member
Dave's method will test the real world bed alignment for twist and is a very needed test in my view. You also need Ricks way to test the alignment of the headstock to the lathe bed as well. So to make sure the headstock is in alignment with the true run of the lathe bed. The bed also needs to be not only twist free, but flat. All these can be adjusted with correct levelling and tramming.
It takes time to get it right, but once correct becomes a real time saver and makes the machine repeatable no matter where on the length of the bed you are working.
 

Ssonerai

AzB Silver Member
Silver Member
If I had to use a 4-jaw in every operation, I'd go nuts after one day.
There are very few operations in cue making that might require a 4-jaw.

True dat.

That's why i said go "all old school"
OTOH, in combination with a steady, it is stone axe reliable. And about as fast as tweaking my adjust-tru's for a one time operation, such as lathe bed checking.

Since this particular discussion was started by the OP about the subject of lathe inspection, not cue-making, It's worth considering that any jaw chuck, there's some worry about condition of the jaws. E.g., it is sometimes commented that the downside of a 6 jaw scroll chuck is that on non-yielding surfaces, it often only really only contacts on 4 jaws. Wood of course won't notice.

I often use a miniature 4J as the outboard chuck on the headstock (mostly) used for cue-making. But i am not in production by any stretch; & have mentioned in the past other machines to use (than lathes) if production was a factor for me. I think you already know i use a planer for profiling.

It kind of boils down to where a person feels comfortable. Cue makers tend to use what other cue-makers use. I didn't know any better & just got on using the machines & tooling at hand. :wink:

smt
 
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