Coaxial Indicator Problem

Hi Billy G,
Thank you for your input.
I am doing this not only for my benefit but because it affects all owners of Coax indicators,
Most owners just say "OH" I am happy with mine, But have never tested it. So I do not find there answers very useful.
Are you happy with what the manufacturer tells you ?? Think VW ??
The test is simple.
Short feeler.
Zero radius.
Ensure the feeler travel is horizontal.
Load the end of the feeler against the tool post a little with the cross slide.
Zero all .
Move the cross slide untill the indicator moves 10 divisions.
Take the cross slide reading and divide by 10.
Compare with what the manufacturer says.

Now who will be the first person with a Blake or any other "Quality" indicator to set the standard.
Brian.
 
Mine is an MHC. Don't know much about it the label is mostly unreadable, but the mhc is formed into the plastic case. No name on the indicator or on the face. Says .0005 per division.
10 divisions is .025 on the cross slide. I don't have a fancy dro just an igaging but both it and the cross slide dial agree at .025
 
Thanks to Wyldboar for mentioning the other half it made me think , this is the total movement of the feeler and will allow us to compare resolution , but to compare the axis offset we must divide the answer by 2. this still leaves my indicator having to move .00135" for one division instead of the quoted .0005"
 
Thank you rgray divide the reading by 10 gives .0025"resolution to compare the axis offset divide by 2 = .00125"
Can any one find anything I have missed in this test.
 
Wouldn't you need to account for the 5 to 1 ratio of the lever arm?

Sent from my SM-P600 using Tapatalk
 
OK, I hope I have all the answers for you. I have a Blake CO-AX. I just ran a test like Brian did and to my surprise, I got about the same results. I have had/used a Blake for decades and never noticed the discrepancy in feeler travel verses dial readings. I have only used the CO-AX for centering not for measuring anything. Cosine error, different feeler lengths, feeler angle and whatever else can effect quantitative measurement. "The manufacture also points this out". But why such a gross error? I can see the copy indicators having the same error BECAUSE they copied the design of the original Blake indicator. The error was built into the copy from the original, huh. OK, so now where is this stated dial reading/graduations coming from??? I found out that the space from the bottom of the CO-AX case to one of the feet on the spinning feeler holder gives the correct readings on the dial, imagine that! Kinda meaningless, but that’s the deal. Just use the CO-AX as a centering tool and not for measuring and you will be good to go…Dave.
 
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Do the dials on the various coax indicators show the value? Does it say something like .001"? Or are they just undefined numbers on a scale?
 
I have a question. I just looked at several different brands of co-ax indicators and NONE of them say what each division is. They all say on the dial "AXIS OFFSET .0005"
What does this mean?
 
I have a question. I just looked at several different brands of co-ax indicators and NONE of them say what each division is. They all say on the dial "AXIS OFFSET .0005"
What does this mean?
My Blake manual says: “Dial Graduation is divided such that each division represents .0005 inch of AXIS OFFSET (deviation from true location) when feeler is tracing a diameter of two inches. (varies slightly with feeler angle).”
 
My Blake manual says: “Dial Graduation is divided such that each division represents .0005 inch of AXIS OFFSET (deviation from true location) when feeler is tracing a diameter of two inches. (varies slightly with feeler angle).”
That is what I am talking about. It does not say each division equals .0005" of movement. it says it is axis offset,:dunno: what ever that means. offset from what and where.
I give up. I'm not going to get one of these.:confused:


I know for a fact, that the dial indicators are accurate if you use the arm straight out. when you bend it ( or I should say angle it) the accuracy changes. if you use the auxiliary long arm that comes with it in the case, the accuracy goes out the window. the same is true with the Starrett indicators. they are accurate alone, but if you start using the fancy attachments that comes with it in the case, the accuracy is shot and by a lot depending on the length of said accessory. I think we are chasing our tail here and to get back to the original question, I think there is no clear answer as they don't say that .0005" is readable movement....it is offset .... and for me that makes the waters muddy. That is what I think.
 
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