digital caliper

"Can any1 break this down in English for me?"


That set should be fine. As I said earlier and Dickie agreed with,as long as the instrument is clean and free from defects,measuring pressure is more important than where the calipers came from. Once you use them enough,you'll almost always exceed what the techincal specs say are the tolerances on accuracy and repeatability.

Trust me on this. The machine shop instructor I had at first made you use dial calipers before you were allowed to even have a set of digitals in your hand,and would often spot-check you on some random object against what he got on his calipers.

His reasoning for this is that such discrepancies can cause problems between co-workers in an actual machine shop environment,and that by developing genuine skill with measuring instruments,you can eliminate a potential source of unwanted bullshit on the job.

Keep in mind,the pressure you want to use on a clearcoated butt or shaftwood is MUCH less than you'd use on aluminum or steel for accurate readings. For this,I tend to use the thicker part on my calipers for measuring shafts. I also rotate the shaft 1/2 turn and re-check.

To be honest though,I use a 0-1" Mitotoyo digital mike (reads to .00005,30 bucks at a pawn shop,matches my calipers),or depending on my mood,a Starrett 0-1" vernier mike my grandfather gave me as much as I use calipers.

I never use the metric functions on any of my digital stuff,as I was drilled in school on being able to do the standard/metric conversion in my head for anything under an inch. I do know,however that there are certain import calipers that will also read out in fractions.

The only cues I've ever really needed to spec out the butt on were my own,and those were only joint,butt cap,and approximate middle of the wrap. Tommy D.
 
hangemhigh said:
China Harbor (Harbor Freight) has what you need, in 6". I prefer Starrett, in 6" too.
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I have a harbor freight 6'' and a Mitutoyo 8" . The Mitutoyo is much better and more consistant. The PAV brand from Switzerland is the best I have. They have prismatic ways instead box type like most others. But the PAV and Mitutoyo are top dollar to buy , but reflect it in their service life.
One of my Mitutoyo calipers is from 1987 and is still quite good.Better than the cheap 6".
If you are wanting accuracy better than .001 inches, you need micrometers and bore gauges.
Neil
 
You said when you close the jaws onto themselves, you can repeat the zero reading.

Try measuring something metal instead of your pool cue. The round shank of a phillips screwdriver would be a good choice that you are likely to have. A drill bit is another good choice that you might have at home.

Try measuring this several times and see if you can get consistent readings. The reason I suggest this is to make sure the taper of the pool cue is not affecting your measurements, even though you believe you are measuring the same place on the cue every time.

If you still get measurement variation, then its either your technique, or the calipers. Try measuring with different pressures on the knife edges of the jaws, and then on the part of the jaws closest to the bar of the calipers. If the measurements on the knife edges vary a lot, but the measurements towards the bar do not, that probably means you are getting flex in the jaws. This could be due to the material (for example if you bought a plastic set of calipers) or due to the jaw being loose. There should be two small screws on the top of the moving jaw. There should also be a thumbscrew. You can try gently tightening the 2 small screws 1/8 turn at a time. You don't want them so tight that they make moving the jaw difficult. This will prevent the jaw from rocking back and forth on the bar, giving you poor measurements.

The thumb screw is meant to lock the jaw in place. It is not meant as an adjustment for the tightness of the jaw when moving it.

Also, as mentioned before, besides consistent measuring pressure, you have to make sure you are not cocking the jaws. Experiment with rocking the calipers side to side so you can see how it affects the measurement.

How repeatable should your measurements be:

You should be able to get .001 inch (.025mm) repeat measurements on the screwdriver or drill bit if your technique is good and the calipers are decent quality.
 
iusedtoberich said:
You said when you close the jaws onto themselves, you can repeat the zero reading.

Try measuring something metal instead of your pool cue. The round shank of a phillips screwdriver would be a good choice that you are likely to have. A drill bit is another good choice that you might have at home.

Try measuring this several times and see if you can get consistent readings. The reason I suggest this is to make sure the taper of the pool cue is not affecting your measurements, even though you believe you are measuring the same place on the cue every time.

If you still get measurement variation, then its either your technique, or the calipers. Try measuring with different pressures on the knife edges of the jaws, and then on the part of the jaws closest to the bar of the calipers. If the measurements on the knife edges vary a lot, but the measurements towards the bar do not, that probably means you are getting flex in the jaws. This could be due to the material (for example if you bought a plastic set of calipers) or due to the jaw being loose. There should be two small screws on the top of the moving jaw. There should also be a thumbscrew. You can try gently tightening the 2 small screws 1/8 turn at a time. You don't want them so tight that they make moving the jaw difficult. This will prevent the jaw from rocking back and forth on the bar, giving you poor measurements.

The thumb screw is meant to lock the jaw in place. It is not meant as an adjustment for the tightness of the jaw when moving it.

Also, as mentioned before, besides consistent measuring pressure, you have to make sure you are not cocking the jaws. Experiment with rocking the calipers side to side so you can see how it affects the measurement.

How repeatable should your measurements be:

You should be able to get .001 inch (.025mm) repeat measurements on the screwdriver or drill bit if your technique is good and the calipers are decent quality.
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Thanks I will try this later. I did do the rocking method as the though of the cocking idea crossed my mind. I will try practicing a bit more b4 I deam them a POS.

Thank all for your help you guys rock.
 
Soulcoma said:
Thanks I will try this later. I did do the rocking method as the though of the cocking idea crossed my mind. I will try practicing a bit more b4 I deam them a POS.

Thank all for your help you guys rock.
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Most probable cause is not having the calipers perpendicular to the piece you are measuring. Any deviation will give you strange numbers.
 
Soulcoma said:
ok well either this caliper I got is a total POS or I have no Idea how to use this correctly.

I can measure the same shaft in the same spot 20 times and 20 times I get a different reading.

I have 2 Meucci Black Dot shafts that according to meucci are standard 12.75mm. However I can get anywhere from 12.98mm to 13.12mm. Have 2 314 shafts one reads anywhere from 12.83mm to 13.02mm. the other reads anywhere from 12.74mm to 12.98mm.

The way I use the gauge is I close it with no abnormal force and zero it. I open it up then close it and verify zero again. I then open it slightly wider than the shaft tip and then close it the same way as when i was zeroing the gauge. Take reading, open it slightly, close gauge read zero, then remeasure. I do that 20 time and get a different reading everytime. Even if I zero the gauge after each reading.

As far as the jaw on the gauge I use the point where it goes to almost a Cutter use the point where it goes back out of cutter shape as the center reference of the shaft. Shows this in the instructions that came with it. However, it doesn't matter where inside the jaws I use to measure I still get random readings.

I have been messing with this thing for nearly 3hrs and I'm getting Frustrated. Please help. Is it me? Or should I return this POS and bite the bullet and go for one of those Mitutoyo?

Forgot to state this is a $30 Set from Autozone Brand Name is OEM Tools for Professionals.
Specs state:
Measure Range 0-150mm/0-6in, 0-300mm/0-12in
Resolution 0.01mm/0.0005in
Accuracy + or - 0.02mm/0.001in (<100mm)
+ or - 0.03mm/0.001in (>100-200mm)
+ or - 0.04mm/0/0015in (>200-300mm)
Repeatability 0.01mm/0.0005in
Max measuring speed 1.5m/sec, 60in/sec
Measuring system Linear capacitive measuring system
Display LCD
Power One silver oxide battery 1.55v, type LR44
Capacity 180Mah
Working Temperature 5 degrees C - 40 degrees C/41 degrees F - 104 degrees F
Influence of humidity Not important under 80% of relative humidty

Can any1 break this down in English for me?
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Here could be the deal. It may require a little more force to be repeatable. Try testing it on a piece of metal you don't worry about making a mark and see it is repeats. Also, if the jaws are square an say an 1/8 of an inch wide, you may not have them squared on the shaft due to it being tapered. It would not take much, we are only talking about thousandths. Another thing, you should only be measuring in thousandths and not increments of MM. Me personally, I don't even have a digital, I only have dial, (maybe I am just old) and I always use the thin front part of the tool to measure. They repeat perfect every time and I mean every time.
 
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I believe that technique is more important for caliper use than for micrometer use. It is sometimes tricky to get the calipers perfectly aligned and square with the piece to be measured. Then you can have the issue of the jaw edges digging into softer material like wood or plastic. Combined it is quite easy to get deviations of a few though over repeated measurements. This says nothing of the errors caused by trying to measure a tapered cone, where up-or-down the shaft is larger/smaller, something that will not make repeatable measurements any easier.

I agree with the others who say to practice on good blocks of hard materials. I tend to use my 1-2-3 blocks for this purpose (they are much easier to use than standards imo). But if I want good measurements I'll use micrometers if possible. With ratcheting thimbles the pressure problem goes away, and they seem easier to get square due to the larger area of the anvils compared to the thin jaws of a caliper. You also don't have the long lever to control (try making small <1" repeatable measurements with an 18" caliper and you'll see what I mean).

Dave
 
Soulcoma said:
I want to buy a digital caliper so I can measure shaft size joint size, butt size, etc.

THanks
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I quoted this post, the OP's, because it seems to be the most relevant to what I'd like to add.

I think that (and would greatly appreciate if) every owner of a cue that had any thoughts of ever ordering an aftermarket shaft, either owned a set of calipers or knew where they could use a set, prior to ordering their new shaft.
Trust me, when I build an aftermarket shaft for you, I want to get the jnt. dia. as close to DNP as is humanly possible. But when I'm given a work-order that only say's : "Build 314-2, 3/8x10, BC (black collar)", I'm going to bring it in at .850" because one of the most popular cues out there that uses that pin is McD and that's their dia. for that configuration. I'm actually just hoping to get lucky by playing the odds.

OK, so what about the non-McDs out there that use that thread? What's their jnt. dia.? I use the big pin on my own cues but at .840". I've seen some down around .820". I've also seen them up around .900" and everything in btwn.
A couple thou per side isn't a big deal considering. But too much more than that and you ain't going to like it; not on a $250 shaft anyway. And that's the point of this post. Buy a set of cals and use them. Hey, they're cheap and save you from ever having to say, "WTF, this ain't the way I ordered this shaft." Actually, it is because you didn't specify a diameter.
A usable set of cals can be had on eBay for $25, delivered to your door. You don't need B&S, Starrett or any other high-dollar set. You're not making bolts for NASA.
But when you're paying $200/250 for an LD shaft, a few bucks spent on cals is cheap money to insure that your shaft fits properly. My job is to make you happy with your purchase. A little help from you and I can make this happen.

A set of calipers is likely to be with you the rest of your life. Once you get them, you're going to start measuring everything in sight. You'll know your tip dia., ferrule, jnt., butt, everything and you'll probably plot the taper of your shaft too. Have fun.

Thank You for allowing me to post some thoughts I've had for a while in a thread that is somewhat on topic.
 
KJ Cues said:
I quoted this post, the OP's, because it seems to be the most relevant to what I'd like to add.

I think that (and would greatly appreciate if) every owner of a cue that had any thoughts of ever ordering an aftermarket shaft, either owned a set of calipers or knew where they could use a set, prior to ordering their new shaft.
Trust me, when I build an aftermarket shaft for you, I want to get the jnt. dia. as close to DNP as is humanly possible. But when I'm given a work-order that only say's : "Build 314-2, 3/8x10, BC (black collar)", I'm going to bring it in at .850" because one of the most popular cues out there that uses that pin is McD and that's their dia. for that configuration. I'm actually just hoping to get lucky by playing the odds.

OK, so what about the non-McDs out there that use that thread? What's their jnt. dia.? I use the big pin on my own cues but at .840". I've seen some down around .820". I've also seen them up around .900" and everything in btwn.
A couple thou per side isn't a big deal considering. But too much more than that and you ain't going to like it; not on a $250 shaft anyway. And that's the point of this post. Buy a set of cals and use them. Hey, they're cheap and save you from ever having to say, "WTF, this ain't the way I ordered this shaft." Actually, it is because you didn't specify a diameter.
A usable set of cals can be had on eBay for $25, delivered to your door. You don't need B&S, Starrett or any other high-dollar set. You're not making bolts for NASA.
But when you're paying $200/250 for an LD shaft, a few bucks spent on cals is cheap money to insure that your shaft fits properly. My job is to make you happy with your purchase. A little help from you and I can make this happen.

A set of calipers is likely to be with you the rest of your life. Once you get them, you're going to start measuring everything in sight. You'll know your tip dia., ferrule, jnt., butt, everything and you'll probably plot the taper of your shaft too. Have fun.

Thank You for allowing me to post some thoughts I've had for a while in a thread that is somewhat on topic.
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That is exactly the point I was getting at. You just made it a lot more clearly. I'm still fairly new to pool considering that most of you all have been playing most of your lives. I only really been playing for about 5 years. and I'm now starting to tinker with different tips joint materials and so on. and as I buy something I'd like to know the diameter, and joint size for that exact reason. So 1, I can sell it and give as much information as possible. But 2, and most imortantly. be able to use it all as a guide for myself. SO I know what I like and don't like so that I can go back to my Cue Maker and give im all the specifics that I care to have in my custom Shaft or Cue for that matter. Like stated in about a million posts on every possible pool forum, What cue is best? That is the one that you are the best with. Don't mater if it's a broom handle or a $10,000 cue if you like then it's best for you.

Back to my last diagnois. I still believe these calipers are crap. I have tried practicing with all different tensions/pressures, rocking method, and about everything inbetween. On a screwdriver with a 1/4" hex shank I still can't get it to repeat consistantly no matter the pressure used or whatever. It is close but is this good enough? Esspecially for the joint size for the purpose of getting a custom shaft made?

The shank is 1/4". I measure .247" - .249" regularly.
or in mm I measure 6.25mm - 6.32mm mostly getting 6.30mm

Is tis good or shuld I return them?
 
Absolutely no offense intended but I think you're going to have to have someone who knows how to use calipers, sit you down and show you.
I doubt that your cals are defective because they are tested and calibrated before they leave the factory. You just need to learn how to use/read them.
 
OK, I'm going to suggest you return them and get another set. At this point my thoughts are that you have convinced yourself that they are no good, and need to move on. I predict that the next set will perform about the same, and hopefully this will lead to improvements in technique.

Like KJ, I mean no offense. We've all been there. And if you think getting reliable repeatable readings from a caliper is difficult, try measuring bores using one of these :

Dave <-- still not over the "what square is square" issue and may need professional help soon :o
 

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No Offence taken. It probably is me but I seem to have tried what has been suggested. I'm a fairly technical guy so these don't seem to far out in left field for me to understand. I'm willing to learn if any of could maybe do a demo video and email it to me it would make me a lot more confident that I'm doing it correctly. Thanks again Rob
 
Harbor freight, http://www.harborfreightusa.com/usa/itemdisplay/displayItem.do?itemid=47257
This is all that I use, they are cheap and work well. I have about 4 of them in my shop and 2 in backup, and they all show the same readings when compared. I have a coupon that is good for up to Five of them for the price of $9.99 each, but it's only good in the store, not internet sales. At this price, if they aren't working right, throw them out and move to the next. If you don't have a Harbor freight store near you, just PM me, I have one about 5 minutes from my house, I'll pick them up and ship them to you for actual cost. Just let me know. They come with a case and extra battery. For what you want it for, It will work just fine. The only problem I have had was I dropped one, and it broke... can't complain about that:grin:
Dave
 
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The problem with often cheap or inaccurate equipment,is it usually raises it's inadequcies when a dimension is taken and someone else makes the part.Unless the equipment is made to traceable standards,the dimensions can not be relied upon.
In such cases, I recomend people to take the item to an engineering shop where they have the correct measuring equipment and can use it reliably.
This saves everyone the headache afterwards.
 
IMO there are 2 things (at least) that you should never skimp on. A top quality Starrett level and a top quality set of calipers. :grin:
 
Get a test standard

Get a gauge block and use it to compare mics. Then when you can get very close readings start measuring finished cues. The goal is to measure without leaving any mark in the finish, and get good readings. Then progress to raw wood, and remember that if the wood is not super smooth the little nibs will play havoc with your measurements. develop a consistent touch or feel for the caliper, something you can repeat every time. It is almost like developing a stroke in pool.
 
Soulcoma said:
I want to buy a digital caliper so I can measure shaft size joint size, butt size, etc. There are so many out there not sure if there is certain brand that any of you use for the best accuracy.

THanks
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dear sweet clueless one:

accuracy is in the eyes of the reader not of the caliper......
OKAY, here is the deal.....calipers are accurate but only depending upon who reads them. In my shop I always try to have laying around at least 6 DIAL, not digital, calipers, which can be adjusted at anytime to ZERO and have an accuracy of 0.0001" as long as my eyes are good and I have the correct reading glasses around my neck. For the price of these 6 DIAL calipers [14.95 @ plus postage] I can buy one DIGITAL caliper, which in three months after having been dropped a few times, etc, etc, will go on the fritz and now you gotta spend another $100 [buy STARRETT, buy AMERICAN is you go this route----China shit is what I buy for again $14.95 @ six at a time....once a year.......most accurate are even calipers called verniers but most people under 50 will have no clue how to use these...again accuracy to 0.0001" is possible but see what number your battery operated toy digital will give you. 0.001 if luck.
When you get as old as I am you are allowed to be an a%%%%%h****le.
Call me with any questions....no pm's 734-428-1161
 
As always, excellent advice from Dr. Dieckman...

And, I'm under 50 but can operate a vernier (an Aerospace background helps). BUT, they certainly do suck to read, and are very 'feel' dependant- when you get down to tenths, pressure can be a killer. I have used verniers up to 36" and you can 'crush' several thousanths pretty easily out that large...
 
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