Coaxial Indicator Problem

I have a question on your test Brian. You are testing a Co-Axial Indicator. How many positions are you checking it at. IMHO you would need to check it at a minimum of 4 locations and take the average of all 4. More positions would prove more accurate. The killer is that even a Blake was never meant to be accurate. As Mark and others have said, it is an expensive center finder. Blake claims .0002 center accuracy. That is closer than most will ever need. Now I bid you all good bye. I can add no more to this thread.

"Billy G"
 
And as my final thought on this. Bill said a key word " .0002 CENTER accuracy" is the claim.
 
I just solved my CO-AX discrepancy, actually two of them. First, and this is I believe for Brian also. Initially I set-up the CO-AX as Brian did on the lathe and used the cross slide as a calibrated translator. Big mistake, if you use the cross slide, the dial on the cross slide does not read 1 to 1. That dial is made to read for diameters. My second mistake was assuming the small feeler I had was 2” long, it’s more like 1 1/2”. After I undid my mistakes the Blake does read accurately…Dave
 
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Well we appear to have thrashed this one to death, and the answer seems to be, Just use it and don't question it.
Thanks to everyone that has taken part your input is much appreciated.
And Mark I don't think any feathers have been ruffled this is possibly the only site that a discussion like this can take place in a gentlemanly manner.
Brian.
 
The paper says ..0005 dia. and the op is measuring in radius.
 
The indicator is a center finder. What difference does it make. It indicates minus to plus with the half way mark being center ( -.0001 ---- 0.0 ---- +.0001) that is a .0002 margin of center error just as it says. That's close enough for me.

"Billy G"
 
BRIAN said:
Just lately I have had cause to question the accuracy of my coaxial indicator. so as a test I held the stem in the lathe 3 jaw. and placed the end of the short feeler ( the most accurate ) against the tool post zeroed the indicator -- the cross slide dial and the digital read out. fed in the cros slide to give one division on the Co ax -- said to be .0005" offset,
And the dial and digital read out read about .0025" this did not look good. so to get better accuracy I went to 10 divisions and divided the result by 10 and came up with .0027"per div the long feeler gave a figure of.0064" per div.
View attachment 126830

The information with the indicator defiantly says :0005" per div offset.

View attachment 126831
So confused and just a bit annoyed I placed a dial indicator against the body of the co ax and lo and behold one division on the co ax is .0005" on the indicator. IT's the dial resolution not the indicator.
How is that for a useless piece of information??
View attachment 126832


The manufacturers have forgotten about the ratio of the feeler arm. Test yours you may be surprised.

I am waiting for a reply from the suppliers
Brian is not a happy boy.
Click to expand...
Amateurs tend to beat the wrong end of a dead horse
 
Used my recently acquired Blake for the first time today.
Wow!!
The Zero-it goes to the back of the drawer.


Daryl
MN
 
coaxial DTI are only meant to indicate/show an offset exists. Not meant to measure a defined offset. they will help to locate a spinning spindle to the center of a hole. The designed purpose.Some may find other uses,but defined off set should not be one.
 
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