Very nice video on test indictors, in my years of experience, I have found that they one of the most misunderstood measuring tools used. Many people could make good use of your video. Scott
Another interesting note about test indicators: some test indicators (like your Interapid) are most accurate with the probe set 12-degrees to the measured surface. And others (Mitutoyo, Compac, et al) are designed to be used with the probe angle at 0-degrees (tangential). It's good to keep this in mind when buying, and using dial test indicators. Thanks for the video!
I also have a Federal indicator that also reads at 12 degrees. Both Federal and Interapid state that it’s easier to set up. I also have the 312B 3, and honestly, I can’t really say that it’s easier one way other other, but they’re all easy.
Hey Dale, Nicely done. Lots of folks get tripped up on Cosine error. You have a very nice collection of test indicators. Thanks for sharing. All the best, Tom
Here's a funny side note about my test indicator collection. Little over 2 years ago I did have any, and with in 4 weeks I collected over 7 of them. Be careful what you look for. :-0
I now know where I went wrong a few years back When I made several out of tolerance parts in bronze ... I lost that job for the blunder and I could not for the live of me figure what I had done wrong I now know thank you
This was a perfect explanation for me. I just received an Interapid test indicator as part of a estate. It was my buddies father's that just passed away and my friend gave it to me. Having never used a test indicator I really needed this video, thank you.
Hey Dale, Excellent explanation on indicators. A couple things I would like to call to your attention. The value on the face of each instrument that you called the “accuracy” is actually the resolution the instrument, not its accuracy. The rule of thumb for accuracy is for it to be 10x the resolution. On the dial indicators, the part that moves in and out of the instrument is called the “rack”, only on the test indicators it is the “probe”. Keep the great videos coming.
Hi Dale, A test indicator is normally only used as a comparison purpose, not really as a precise direct measure, compared to the dial indicator, exactly as you said cause of that angle... Good share, Pierre
Thanks, well worth the time to watch. I see these things set up at crazy angles all the time. Just learning that the needle has to be parallel to the surface and the dial vertical will make me better able to use these. I look forward to getting mine in the mail soon. My surface plate is already home.
Excellent tutorial on taking accurate measurements. Just goes to show you its not how good the tools are, but how you use the tools. Looking forward to the next video. Cheers, Dave
Hot Dog! I had no idea - I just picked up a lathe that looks just like the one you have in the background! It came with a few test indicators, and I have a couple of dial indicators. But I had no idea that the use of the test indicator was so critical in terms of set up. Thanks for the tips.
Nicely done video - well recorded and informative. Also you have a very crisp style of explaining things. Just discovered your channel and you sure just gained a subscriber :)
The situation is that very often, as in setting up my new 200mm Buck Adjust Tru chuck, is that we don’t have to know exactly how far off it is, just that we can get it to a minimum of concentric error. If my reading is off by a tenth, it doesn’t matter, if that’s the closest I can do.
Hello Dale That was excellent discussion/demonstration! My mentor has always stressed the position of the test indicator and your video explains it. ATB Chuck
I always consider a test indicator to be a relative reading, and I only use them to center parts, etc-instead of considering the numbers to be actual measurements. Thanks for the video.
Your TH-cam presence has been missed. Hopefully we will see more from you soon. Thanks for taking the time to produce the fine video content and sharing. Pat
Hey Dale, thanks for all your videos. Quick question, does changing the probe on the indicator would change the result. I mean if replacing a longer probe to indicator that came with a short one.??
The length of probe matters on the test indicator only if you are depending on the values of each division to scale correctly. But if say you needed to reach farther to a feature so you could knock it on center then you'll only need to know the general swing in runout and if it's positive or negative. In that case probe length is arbitrary. You could also do the math, dividing the original probe lenght by the new probe length to get the value to factor you dial divisions by. For example if the original probe length is (20mm or 3/4in) and the new probe is (40mm or 1-1/2in) then 20÷40=0.5, then divide not mutiply you indicator reading by that factor. This would be for a situation say where you had to hold a minimum specified concentricity or runout per the print. Remember it's the length of the probe to it's pivot point and not to the base of the probes thread. It's actually a good way to measure and you'll quickly discover if you need it once a year then put the money into something more useful. If you end up needing it more and more then it makes sense to have a dedicated indicator and since they are vulnerable to accidents where the tip gets broken off, you'll already have a spare. Cheers!
What a great video. I have a garage sale find starett last word test indicator. Just figuring it out on my own has lead me astray so I quit using it (figured it was broken) and use an use dial indicator.
though i have never used one, from what i have read and seen on some authoritative sites, the interapid differs from other test indicators in that it's probe is not to be tangent but rather at an angle to the surface being read. if true, the results of your test would have been somewhat opposite to those for the mitutoyo.
Dale, I know this off the topic, but how do you like your Enco lathe? I am seriously thinking of getting one and would like your thoughts. Thanks for your time and for a great video on indicators. Dave
Hi Swart Rat. The Enco has been a good lathe, and great lathe for the home shop. Some of the nice features are the harden and ground bed ways and the hand scraped dove tail ways for the cross slide. Two things I don't like deal with the tail stock. The #3 mores taper doesn't lock the drill chuck or bit in place, so they have a tendensy to spin under heavy loads. and the tail stock dosent hold well when locked in place. Are you buying a new, or used?
A common "mistake." One usually assumes 0.0001. A good way to avoid the confusion is to use micro-inches. 0.0001 is 100 micro inches. If one says 100 micro inches, there is no confusion. Of course 100 micro inches is more of a mouthful than 1 tenth! Can you tell I am a retired scientist? lol
You guys are all saying the same thing. The problem is with the narrator of the video. He is not being careful when he discusses the limits of "accuracy" (of course it's really just stating the nominal measurement corresponding to the smallest divisions on the dial face). At 5:01, he states the Mitutoyo test indicator is "accurate to ten thousands of an inch." I listened carefully, and he gets it wrong twice, once at 5:01 and again at 5:08. He knows the difference, but he does not use the correct words. To be correct, he should have said: "...is accurate to one ten-thousandth of an inch." As most of us understand, units of one ten-thousandth of an inch are commonly (though somewhat confusingly) referred to as 'tenths', as in tenths of a thousandth, which of course is the same as one ten-thousandths. For you metric system fans, we're talking about 2.54 microns. Arguably, 'tenths' is actually a more practical unit. To put 'tenths' into perspective, consider this: a typical human red blood cell has a diameter of 3 'tenths'. So be sure to wipe all the blood off your work and indicator surfaces before attempting precision measurements... As for micro inches, well it's a nice idea, but in all the machining videos and discussion forums I've looked at, I don't recall anyone using micro inches as a unit of measure. So it might be a great idea, but, like Esperanto, it has failed to take hold...so indeed, 'tenths' it is!
You kind of alluded to it but instead of saying tangent to the piece it would be better to have said the specified angle. For example the 312b-3 (really all the 312s) wants the angle of the probe to the surface to be 12°. In their documentation they give you a correction for other angles if the 12° isn't possible.
Hi Flip de boer, Yes, in theory. The steeper angle will give you a more sensitive reading. Another way to do it would be to use a longer probe. The best way to get a more detailed reading is to use a more accurate tool. :-)
Technical point: the graduations refer to the precision of the instrument, not the accuracy. Consider a 6" scale compared to a 6" gage block. The scale is the more precise instrument, the gage block, more accurate.
What? All of them have DIALS and all of them INDICATE. The only difference is the range of measurement, the precision of measurement, and the plunger type probe vs. the stylus type probe.
I will offer a caution to this 8 year old video even though it is not likely to be read. While Interapid is the class act, Rolls Royce of test indicators and has twice the range or more of competing indicators, they are extremely prone to unintended accidental damage resulting in damage to the change of direction mechanism. If indicating a static measurement as demonstrated with the height gage and surface gage this damage will not affect the indicated measurement. BUT if indicating a dynamic function such as runout, any lash in the internal mechanism will not capture this lash in the needle movement, resulting in a false measurement. I have seen nearly as much as .002" lash in a damaged Interapid.0005" indicators that was previously unobserved by the daily users. This amount of error is pretty easy to suspect by a skilled operator, but smaller error is more easily unobserved. A proper calibration tool such as a Cadillac gage is required to validate a suspected damaged indicator. This gage us likely secured in the inspection lab and not readily available to the shop floor user. In my 40+ years of experience, I have discovered numerous Interapid indicators with this hidden damage in normal daily production use, most commonly with shop owned and multiple user tools. I own 40+ high quality indicators from several premium manufacturers, but only one Interapid (that I picked up used for cheap). I don't trust them, unless validated. The hobby user is unlikely to have adequate validation inspection equipment. The benefits of the Interapid are the large range of of measurement compared to the competition and the snob factor of owning the most costly. An Interapid "tenth" (.0001) indicator has a range of about .020" compared to .008" of a comparable Mitutoyo or Brown and Sharp. This is a huge advantage when correcting tool holder rotational error on a crashed turret lathe. But if it has lash damage, you are screwed. Another issue that frustrates me is that Interapid uses its own mounting system requiring special mag base adapters. Your beloved Noga holder will hold every other style out of the box, but requires additional expense and setup to hold the Interapid. You may have noticed that Dale didn't use his Interapid in his test demonstration, probably because the height gage and surface gage were not equipped to hold the Interapid. I have many mag bases, height gages, surface gages, etc, and the ability to swap between holders easily allows me to select the setup most conducive to job without additional fixturing changes to hold the Interapid. There are some knock off copies of the Interapid design, but I have no experience with the less prestigious makers. The cost of the Interapid can be more than double the cost of a more rugged Mitutoyo or Brown and Sharp. Starrett indicators are lovely, and are priced in a mid point between these extremes. I am a tool snob and prefer and value the best, but I strongly caution about owning and using the Interapid unless you have deep pockets and provision to validate the Interapid. My Brown and Sharp .00005" indicator has a limited range of only .004". When I purchased it for a very special requirement, it was affordable and readily available. I really had no other purchase options. This is a specialized test indicator. I worked in a " high precision" production shop of 100 machinists, and I was the first to own and require this accuracy. I own my Interapid because I can and mostly for bragging rights. I don't use it. Buy yours, treat it with more caution than your other brands, and don't ever loan it!
Very nice video on test indictors, in my years of experience, I have found that they one of the most misunderstood measuring tools used. Many people could make good use of your video.
Scott
Another interesting note about test indicators: some test indicators (like your Interapid) are most accurate with the probe set 12-degrees to the measured surface. And others (Mitutoyo, Compac, et al) are designed to be used with the probe angle at 0-degrees (tangential). It's good to keep this in mind when buying, and using dial test indicators.
Thanks for the video!
I also have a Federal indicator that also reads at 12 degrees. Both Federal and Interapid state that it’s easier to set up. I also have the 312B 3, and honestly, I can’t really say that it’s easier one way other other, but they’re all easy.
Hey Dale,
Nicely done. Lots of folks get tripped up on Cosine error. You have a very nice collection of test indicators. Thanks for sharing.
All the best,
Tom
Here's a funny side note about my test indicator collection. Little over 2 years ago I did have any, and with in 4 weeks I collected over 7 of them. Be careful what you look for. :-0
I now know where I went wrong a few years back
When I made several out of tolerance parts in bronze ...
I lost that job for the blunder and I could not for the live of me figure what I had done wrong
I now know thank you
This was a perfect explanation for me. I just received an Interapid test indicator as part of a estate. It was my buddies father's that just passed away and my friend gave it to me. Having never used a test indicator I really needed this video, thank you.
Hey Dale,
Excellent explanation on indicators.
A couple things I would like to call to your attention.
The value on the face of each instrument that you called the “accuracy” is actually the resolution the instrument, not its accuracy. The rule of thumb for accuracy is for it to be 10x the resolution.
On the dial indicators, the part that moves in and out of the instrument is called the “rack”, only on the test indicators it is the “probe”.
Keep the great videos coming.
Hi Dale,
A test indicator is normally only used as a comparison purpose, not really as a precise direct measure, compared to the dial indicator, exactly as you said cause of that angle...
Good share,
Pierre
Thanks, well worth the time to watch. I see these things set up at crazy angles all the time. Just learning that the needle has to be parallel to the surface and the dial vertical will make me better able to use these. I look forward to getting mine in the mail soon. My surface plate is already home.
Your videos are great! Having a photography background clearly translated well into your editing and production quality!
+Roger Kimball
thanks for your comment
I'm glad you showed this video, I did not know that about the test indicator. Thank you
Finally got around to watching....great vid Dale! Thanks!
Very good info.
I wish I would have learned these tips years ago!
Excellent tutorial on taking accurate measurements.
Just goes to show you its not how good the tools are, but how you use the tools.
Looking forward to the next video.
Cheers,
Dave
Excellant, as a newbie to precision metal work, you have just open my eye's to how these test indicators work. Thanks
+David Haxton
Im glad you liked it
Hot Dog! I had no idea - I just picked up a lathe that looks just like the one you have in the background! It came with a few test indicators, and I have a couple of dial indicators. But I had no idea that the use of the test indicator was so critical in terms of set up. Thanks for the tips.
I had no idea. Thanks Dale.
Excellent video with very useful information, well presented. Thanks for sharing!
Nicely done video - well recorded and informative. Also you have a very crisp style of explaining things. Just discovered your channel and you sure just gained a subscriber :)
Thanks
The situation is that very often, as in setting up my new 200mm Buck Adjust Tru chuck, is that we don’t have to know exactly how far off it is, just that we can get it to a minimum of concentric error. If my reading is off by a tenth, it doesn’t matter, if that’s the closest I can do.
Great video Dale. Learned something new. Keep em coming
Thanks for the encouragement :-)
Hello Dale
That was excellent discussion/demonstration! My mentor has always stressed the position of the test indicator and your video explains it.
ATB
Chuck
Thanks.
Its always good to here from another You tuber
Good important information, thank for the demo.
I always consider a test indicator to be a relative reading, and I only use them to center parts, etc-instead of considering the numbers to be actual measurements.
Thanks for the video.
Glad you enjoyed it .
Smart!
They aren't exact.
Your TH-cam presence has been missed. Hopefully we will see more from you soon.
Thanks for taking the time to produce the fine video content and sharing.
Pat
Thanks for your comment. I have a big crazy and fun announcement coming soon, The news will explain my absence.
good info man. thanks for posting
Outstanding! My charts are going to get better.
thanks, nice demo. thanks for sharing.
Thanks for your explanation. Keep the videos coming, and keep up the good work. Like your videos,
Thanks. Im working on getting more videos out.:-)
Nicely produced, but strangely no mention of the very-necessary-to-know clutch on the DTI probe.
Thanks, you just solved one of my problems - :-)
Hey Dale, thanks for all your videos. Quick question, does changing the probe on the indicator would change the result. I mean if replacing a longer probe to indicator that came with a short one.??
The length of probe matters on the test indicator only if you are depending on the values of each division to scale correctly. But if say you needed to reach farther to a feature so you could knock it on center then you'll only need to know the general swing in runout and if it's positive or negative. In that case probe length is arbitrary. You could also do the math, dividing the original probe lenght by the new probe length to get the value to factor you dial divisions by. For example if the original probe length is (20mm or 3/4in) and the new probe is (40mm or 1-1/2in) then 20÷40=0.5, then divide not mutiply you indicator reading by that factor. This would be for a situation say where you had to hold a minimum specified concentricity or runout per the print. Remember it's the length of the probe to it's pivot point and not to the base of the probes thread. It's actually a good way to measure and you'll quickly discover if you need it once a year then put the money into something more useful. If you end up needing it more and more then it makes sense to have a dedicated indicator and since they are vulnerable to accidents where the tip gets broken off, you'll already have a spare.
Cheers!
What a great video. I have a garage sale find starett last word test indicator. Just figuring it out on my own has lead me astray so I quit using it (figured it was broken) and use an use dial indicator.
+Micheal Double
Im glade the video helped :-)
thanks so much
though i have never used one, from what i have read and seen on some authoritative sites, the interapid differs from other test indicators in that it's probe is not to be tangent but rather at an angle to the surface being read. if true, the results of your test would have been somewhat opposite to those for the mitutoyo.
Well done, hope to see more - lots of bad habits out in the real world. Not making sure the tip or back plate is tight or mag base that rocks..
Dale,
I know this off the topic, but how do you like your Enco lathe? I am seriously thinking of getting one and would like your thoughts. Thanks for your time and for a great video on indicators.
Dave
Hi Swart Rat.
The Enco has been a good lathe, and great lathe for the home shop. Some of the nice features are the harden and ground bed ways and the hand scraped dove tail ways for the cross slide. Two things I don't like deal with the tail stock. The #3 mores taper doesn't lock the drill chuck or bit in place, so they have a tendensy to spin under heavy loads. and the tail stock dosent hold well when locked in place.
Are you buying a new, or used?
Dale . . . I plan to get in new. Thanks for the input.
Regards,
Dave
How do you know that it is safe to grab the sensing pin and force it to a new position? Is this a universal feature common to all test indicators?
The Interapid is not ten thousanths of an inch reading. It is a tenth of a thousanth reading. A factor of 100 difference!
+Joseph Lippencott 1/1000 * 1/10 = 1/10000
A common "mistake." One usually assumes 0.0001. A good way to avoid the confusion is to use micro-inches. 0.0001 is 100 micro inches. If one says 100 micro inches, there is no confusion. Of course 100 micro inches is more of a mouthful than 1 tenth! Can you tell I am a retired scientist? lol
You guys are all saying the same thing. The problem is with the narrator of the video. He is not being careful when he discusses the limits of "accuracy" (of course it's really just stating the nominal measurement corresponding to the smallest divisions on the dial face). At 5:01, he states the Mitutoyo test indicator is "accurate to ten thousands of an inch." I listened carefully, and he gets it wrong twice, once at 5:01 and again at 5:08. He knows the difference, but he does not use the correct words. To be correct, he should have said: "...is accurate to one ten-thousandth of an inch." As most of us understand, units of one ten-thousandth of an inch are commonly (though somewhat confusingly) referred to as 'tenths', as in tenths of a thousandth, which of course is the same as one ten-thousandths. For you metric system fans, we're talking about 2.54 microns. Arguably, 'tenths' is actually a more practical unit.
To put 'tenths' into perspective, consider this: a typical human red blood cell has a diameter of 3 'tenths'. So be sure to wipe all the blood off your work and indicator surfaces before attempting precision measurements...
As for micro inches, well it's a nice idea, but in all the machining videos and discussion forums I've looked at, I don't recall anyone using micro inches as a unit of measure. So it might be a great idea, but, like Esperanto, it has failed to take hold...so indeed, 'tenths' it is!
Which confusion suggests you should be using microns.
You kind of alluded to it but instead of saying tangent to the piece it would be better to have said the specified angle. For example the 312b-3 (really all the 312s) wants the angle of the probe to the surface to be 12°. In their documentation they give you a correction for other angles if the 12° isn't possible.
Good of you to spot that.
So you can use an angled setup to get more sensitivity (?)
Yes, but the readings would be relative and not absolute...
Hi Flip de boer,
Yes, in theory. The steeper angle will give you a more sensitive reading. Another way to do it would be to use a longer probe. The best way to get a more detailed reading is to use a more accurate tool. :-)
*****
Dale, Wouldn't a shorter probe give a more sensitive reading??
Fred Miller Your right. What is funny I did experiment once that shows that and forgot all about it. thanks for the correction. ;-)
For future videos note the difference between a probe and a stylus.
Technical point: the graduations refer to the precision of the instrument, not the accuracy. Consider a 6" scale compared to a 6" gage block. The scale is the more precise instrument, the gage block, more accurate.
I own a b&s accurate to .00001 and I will probably never use it lol
xsniper3500x so would that be a "hundredths" indicator or a "10 millionths" indicator when using shop talk?
Test indicators are NOT intended to "measure" , they are COMPARITORS. Their readings are intended only as an estimate.
if Interapid is a rolls royce the COMPAC is a Saturn V.
What? All of them have DIALS and all of them INDICATE. The only difference is the range of measurement, the precision of measurement, and the plunger type probe vs. the stylus type probe.
I will offer a caution to this 8 year old video even though it is not likely to be read. While Interapid is the class act, Rolls Royce of test indicators and has twice the range or more of competing indicators, they are extremely prone to unintended accidental damage resulting in damage to the change of direction mechanism. If indicating a static measurement as demonstrated with the height gage and surface gage this damage will not affect the indicated measurement. BUT if indicating a dynamic function such as runout, any lash in the internal mechanism will not capture this lash in the needle movement, resulting in a false measurement. I have seen nearly as much as .002" lash in a damaged Interapid.0005" indicators that was previously unobserved by the daily users. This amount of error is pretty easy to suspect by a skilled operator, but smaller error is more easily unobserved. A proper calibration tool such as a Cadillac gage is required to validate a suspected damaged indicator. This gage us likely secured in the inspection lab and not readily available to the shop floor user. In my 40+ years of experience, I have discovered numerous Interapid indicators with this hidden damage in normal daily production use, most commonly with shop owned and multiple user tools. I own 40+ high quality indicators from several premium manufacturers, but only one Interapid (that I picked up used for cheap). I don't trust them, unless validated. The hobby user is unlikely to have adequate validation inspection equipment.
The benefits of the Interapid are the large range of of measurement compared to the competition and the snob factor of owning the most costly. An Interapid "tenth" (.0001) indicator has a range of about .020" compared to .008" of a comparable Mitutoyo or Brown and Sharp. This is a huge advantage when correcting tool holder rotational error on a crashed turret lathe. But if it has lash damage, you are screwed.
Another issue that frustrates me is that Interapid uses its own mounting system requiring special mag base adapters. Your beloved Noga holder will hold every other style out of the box, but requires additional expense and setup to hold the Interapid. You may have noticed that Dale didn't use his Interapid in his test demonstration, probably because the height gage and surface gage were not equipped to hold the Interapid. I have many mag bases, height gages, surface gages, etc, and the ability to swap between holders easily allows me to select the setup most conducive to job without additional fixturing changes to hold the Interapid. There are some knock off copies of the Interapid design, but I have no experience with the less prestigious makers. The cost of the Interapid can be more than double the cost of a more rugged Mitutoyo or Brown and Sharp. Starrett indicators are lovely, and are priced in a mid point between these extremes.
I am a tool snob and prefer and value the best, but I strongly caution about owning and using the Interapid unless you have deep pockets and provision to validate the Interapid.
My Brown and Sharp .00005" indicator has a limited range of only .004". When I purchased it for a very special requirement, it was affordable and readily available. I really had no other purchase options. This is a specialized test indicator. I worked in a " high precision" production shop of 100 machinists, and I was the first to own and require this accuracy. I own my Interapid because I can and mostly for bragging rights. I don't use it.
Buy yours, treat it with more caution than your other brands, and don't ever loan it!