Question on Dial Test indicator

R

rdfkentucky

Registered
Registered
Joined
Sep 10, 2013
Messages
16
Hi

I purchased a cheap one to learn on and have been reading and watching some videos, but I'm not sure on how the dial is supposed to work. It seems like when I zero it on my vise it locks up the needle and the probe. The instructions don't say nothing. Am I doing something wrong or is the cheap DTI bad?


Rick
 
OK Rick, first things first. Just holding in your hand, can you manipulate the contact and get indicator movement? You do understand that the contact/stem only rotate through a small arc on the bearings in the tip of the body?. It is not omnidirectional. Depending on exactly what indicator you have, you may have an auto-reversing indicator, or one that has a lever to switch sweep directions.

When you bring your vise to position, watch the needle and see if it moves with very light contact. Fractions of ounces. The shaft the contact/stem rides (in the bearings) in at the tip of the body has an axis that must be parallel to your anticipated movement of the contact/stem, which is perpendicular to the vise jaw.

If you know your indicator has 0.0300 travel, as an example, continue to bring the jaw to bear against the movement of the indicator until you have reach approximately half the travel. If if is the lever type, make sure the lever has tensioned the indicator in the proper direction. When you are satisfied that it is at approximately at the midpoint of travel, turn the bezel assembly to zero on the needle. That part is really a matter of personal preference. If you get used to using a DTI like this, you really don't need to zero it unless you are shooting for a given misalignment or taper, or are measuring something as in using it as a comparator. If you are simply sweeping in a vise or mill head, you want to see a minimum of needle deflection, regardless if it is near the dial zero or not. The exact number you are using for reference is immaterial.

Do you have any pictures of your setup? Perhaps I have uncovered your problem, or perhaps I have only confused you, but pictures are always helpful.
 
Tony Wells said:
OK Rick, first things first. Just holding in your hand, can you manipulate the contact and get indicator movement? You do understand that the contact/stem only rotate through a small arc on the bearings in the tip of the body?. It is not omnidirectional. Depending on exactly what indicator you have, you may have an auto-reversing indicator, or one that has a lever to switch sweep directions.

When you bring your vise to position, watch the needle and see if it moves with very light contact. Fractions of ounces. The shaft the contact/stem rides (in the bearings) in at the tip of the body has an axis that must be parallel to your anticipated movement of the contact/stem, which is perpendicular to the vise jaw.

If you know your indicator has 0.0300 travel, as an example, continue to bring the jaw to bear against the movement of the indicator until you have reach approximately half the travel. If if is the lever type, make sure the lever has tensioned the indicator in the proper direction. When you are satisfied that it is at approximately at the midpoint of travel, turn the bezel assembly to zero on the needle. That part is really a matter of personal preference. If you get used to using a DTI like this, you really don't need to zero it unless you are shooting for a given misalignment or taper, or are measuring something as in using it as a comparator. If you are simply sweeping in a vise or mill head, you want to see a minimum of needle deflection, regardless if it is near the dial zero or not. The exact number you are using for reference is immaterial.

Do you have any pictures of your setup? Perhaps I have uncovered your problem, or perhaps I have only confused you, but pictures are always helpful.
Click to expand...

Thanks for your reply. I was trying to figure out what he type of indicator he is using. I've used a Starrett for all my career, it served me well.
 
Well, all he said was test indicator, so that's what I went with. I did think of another possible issue. I have seen people that have only used the standard 1" travel AGD ll indicator, which of course has the stem that plunges "into" the body, and have at first thought the DTI would be used in a similar fashion.

I have a Last Word, used it for many a year, but I prefer the auto reversing feature now, like the BesTest and Interapid have.
 
Tony

I had to work over and didn't get to take a picture. Her is some information on the indicator I got from ENCO. Automatic reversing, max measurment 0.030, Graduation 0.0005, dial reading 0-15-0. I was checking it if I hold it in my hand and have the Zero straight up and the probe straight down, the probe will move in both directions and the needle is showing .0006 on the counter clock direction. If i turn the dial counter clockwise it goes to .0004 and the needle sticks, when turning it in the clock wise position it goes to .0004 and does the same thing. Is this how they work? I hope I'm explaining this so you can understand me. I'm a noobie.
 
OK, so you have verified the direction of the arc movement. That tells you how to present the contact to the work. It must move the contact in that arc to read true. Now, you say when you turn the dial, so I believe you mean the bezel, which normally has small ridges for grip. It should spin with a little drag all the around....no stops on it. Now, the stem that the contact ball (or pear) also will move on a friction (or one few designs, a ratchet type) mount. If you firmly but gently hold the body of the indicator, you are safe to swing the contact as far as it will move, and it should be a little over 180° from its "at rest" position. In other words, it can be used in any position that you set it to, and still have a range of 0.015 in either direction. If, for instance, you put it at about 90° to the indicator body, you could have have the stem and contact vertical in either pointed up or pointed down. It's normal to have the moveable bezel, which is held to the dial face, aligned with the zero, but as I sad, it's not mandatory.

If you are only getting 0.0006 (6 ten thousandths of an inch), that would be a smidgen over the first grad line, which is 0.0005. Are you sure about this? You should be able to read at least the 0.015 movement with NO sticking. If this is new, you could just work it in your hands and see if it loosens up, but if it doesn't give you the 0.015, and feels like you are forcing it, I would return it as defective.
 
If I am understanding you, when you push the tip with the zero on the needle from rest, it should travel .015 in either direction on the dial. If it only reads 4 tenths that aint right. You push these from the side of the contact. You dont come straight down on the tip like a drop indicator. They move front to back not up and down. The face that rotates should not make the needle stick. Is that wha your rotating?
 
rdfkentucky said:
Tony

I had to work over and didn't get to take a picture. Her is some information on the indicator I got from ENCO. Automatic reversing, max measurment 0.030, Graduation 0.0005, dial reading 0-15-0. I was checking it if I hold it in my hand and have the Zero straight up and the probe straight down, the probe will move in both directions and the needle is showing .0006 on the counter clock direction. If i turn the dial counter clockwise it goes to .0004 and the needle sticks, when turning it in the clock wise position it goes to .0004 and does the same thing. Is this how they work? I hope I'm explaining this so you can understand me. I'm a noobie.
Click to expand...

Is this
http://www.use-enco.com/1/1/9862-13-723-2-spi-magnetic-dial-test-indicator-base-sets.html
the unit you have?
 
Sounds like the needle is sticking on the dial, or something else is fowled up. The needle should move smoothly throughout it's range.
 
You must log in or register to reply here.
Back
Top