Adjusting Blake Co-Ax for larger diameters

I picked up a Co-Ax off ebuy a few years ago, and I'm getting my money's worth out of it. Bought the 3" inside feeler, and was stumped on
why it wouldn't pick up on a 1.375 bore...
Manly-man adventures deleted. The secret to adjusting the swept diameter is to pivot the feeler outward. The phillips screw just above the feeler socket is the pivot for the feeler assembly. You can loosen it up or tighten it with the phillips screw / acorn nut. Duh.
To answer the question of what the Co-Ax measures, the dial says (Quote).0005" AXIS
Does that " stand for inches or minutes?
The dial graduation is divided such that each division represents .0005" (0,01mm) of axis offset (deviation from true location) when the feeler is tracing a diameter of two inches. This will vary slightly with feeler angle. - manufacturer's instructions
http://longislandindicator.com/p5.html
Place the appropriate feeler in the indicator rocker bracket and secure it with the thumb screw. Position the rocker bracket on the rocker friction joint such that the small indicator hand is centrally located on its graduation scale when the feeler is in operational contact with the work piece.
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If I understand your question correctly, I believe it means the spindle holding the indicator is .0005" inches "off center line" with the bore you are sweeping.
I have been using a Blake for many, many years and love it. But I never cared about the graduations, I just center it as close as I possible can and go for it.
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26 Jul 2009 23:36:37 -0500 did write/type or cause to appear in rec.crafts.metalworking the following:

    I loved mine, I could center holes, pins, etc, in short minutes - faster than I could any other method, even including the 'set up' time. - pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!
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pyotr filipivich wrote:

(...)
Mine's required service for some time (no round tuit available). Imagine my delight in discovering that Blake will disassemble, clean, reassemble and certify it for only $40!
http://www.blakemanufacturing.com/pages/repairs.html
Cool!
--Winston
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Winston wrote:

Long Island Indicator Service. http://longislandindicator.com /
I found their site to have a better view of the Co-Ax parts http://longislandindicator.com/p110.html
Go with Blake, Long Island wants $152 to repair.
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Louis Ohland wrote:
(...)

Excellent! Thanks, Louis!

I shall.
--Winston
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Tim wrote:

I re-read the terse user instructions, it's .0005" at a two inch diameter, as the diameter changes, the error will depend on the cosine? of the difference.
Centered a 6" square plate on a rotary table. Co-Ax'd the table MT2 bore, locked down the table, then centered the plate.
Then I used a 1/2 cobalt machine screw drill with 135* point and drilled along the diameter. I'll follow up with a roughing end mill to connect all the holes. I'll follow this with a boring head to take it to a finished diameter. More operations to do after this, but this is starting to look like a compound clamp for an import 11x26 lathe.
My Sieg X3 finally got to do some serious chip making.
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These things come with different length probes. Heck if I know what it works out to.
But let me google this for you.
http://www.blakemanufacturing.com/pages/coaxvalues.html
HTH,
Wes
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Wes wrote: > http://www.blakemanufacturing.com/pages/coaxvalues.html
I knew I'd seen it... I'm used to web pages disappearing, so here are the values
Blake CO-AX Indicator Dial Graduation Values      Bore    2"    4"    6" 0    .00056    .00105    .00147 1    .00054     .00103     .00146 2    .00050     .00100     .00145 3    .00044     .00097     .00143 4    .00030     .00093     .00140 5        .00087     .00136 6        .00079     .00132 7        .00069     .00124 8        .00055     .00115 9            .00105 10            .00097 11            .00083 12            .00062
Bore diameter in inches 2", 4", and 6" refer to the feeler Length
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I was fairly curious since I use one of those indicators at work from time to time. I typically just settle for dead nuts ;)
I notice that there is a 800 rpm limit on the indicator. I've never used one with the spindle powered, I've always manually turned the spindle.
Has anyone used one with the spindle under power? I see that is what the long rod is for, to hold the body from rotating.
Wes
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Wes wrote:

They are designed for use under power.
Speed limits are probably due to the limits of the body moving up and down as the feeler rotates. After it goes so fast, perhaps the body or movement inside have too much inertia... Or perhaps it's the bearing surface that the feeler assembly rides on.
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I almost always use mine under power, but I have never used the rod, I just hold the body. I think the only valid purpose for the rod is if you are working to just a couple of tenths or so, and don't want to chance springing the body enough to get an inaccurate reading. I think the only time I don't use mine under power is sweeping my spindle square with the table. I burned a 10" circle out of half in plate, and had it clean up on a Blanchard, for sweeping the spindle. Makes short work out of squaring the head on a mill.
I would think the 800 rpm limit is a moot point anyway. You need to be able to read the dial every half revolution. I always select my lowest speed and let'er go. Then just adjust until dead nuts same as you.
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I gave under power in a bridgeport going as slow as possible. I couldn't read it and react fast enough. I stuck to my normal method, swing it from X+ to X-, note deviation, halve it, do the same for Y+ Y-, repeat.
If I could have got it down to 1 rpm, I probably could have used it under power.
It was nice to know though just how close I was indicating. Louis had a darn good question.
Wes
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