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Micing my crank for the 225 - readouts
https://www.slantsix.org/forum/viewtopic.php?t=51908		 Page 1 of 1
Author:  Eatkinson [ Tue Apr 30, 2013 3:46 pm ]
Post subject:  Micing my crank for the 225 - readouts
I'm busily micing my crank for my 225 rebuild. Picked up a set of Harbor Freight (I know..) micrometers. They only measure down to .001", but was hoping they'd work.

Here's photos of my readouts. Even if I'm not reading to the .0001" there seems to be something wrong because I'm reading that I'm OVER spec on my readouts. FSM states main bearings spec is 2.7495-2.7505. Don't understand how that could be, unless I'm totally reading the micrometer wrong. I made sure to calibrate the micrometer to 0, then to get the anchor and spindle positioned correctly on the main journals, taking into account I probably didn't want to measure in the middle because there's the oil groove there, so possibly less wear, so I offset the pins from the journal center to get an accurate wear reading.

Here's the photos, what do you all think? With the exception of MB #4, they all seem to be around the same readout, which makes me think I'm reading the mic wrong....:

General Setup

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Micrometer I'm using

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MAIN 1 HORIZONTAL READOUT
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MAIN 1 VERTICAL READOUT
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MAIN 2 HORIZONTAL READOUT
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MAIN 2 VERTICAL READOUT
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MAIN 3 HORIZONTAL READOUT
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MAIN 3 VERTICAL READOUT
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MAIN 4 HORIZONTAL READOUT
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MAIN 4 VERTICAL READOUT
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Author:  Fopar [ Tue Apr 30, 2013 4:33 pm ]
Post subject: 
I read that as 2.751"

Richard
Author:  Ssg Pohlman [ Tue Apr 30, 2013 6:40 pm ]
Post subject: 
Same, 2.751.
And don't look past the HB tools. Part of my job skill I learned at Ft Lee is micrometers and torque wrenches. I checked my HB TQ wrench and was well within limits.

There's also a magazine that done a write up on them as well, turned out good in it also. They even used one of the digital extension style and worked great.
Author:  emsvitil [ Tue Apr 30, 2013 6:41 pm ]
Post subject: 
All but the last one are around 2.7495 which I see as 2.7513
Author:  emsvitil [ Tue Apr 30, 2013 6:43 pm ]
Post subject: 
Lock it at 2.7505 and use it as a 'go/no go' gauge
Author:  emsvitil [ Tue Apr 30, 2013 6:52 pm ]
Post subject: 
Calibrate the 0-1" to 0

Then measure the 1" calibration with the 0-1" mic

If it's 1", calibrate the 1-2" with the 1" calibrator

If it's not 1" calibrate the 1-2" to whatever the 1" calibrator actually is (i.e .999 1.0001 whatever)

Now you have the 0-1 and 1-2 calibrated.

Measure the 2" calibrator with the 1-2 mic and do the above to get the 2-3" mic calibrated...........
Author:  Fopar [ Tue Apr 30, 2013 7:19 pm ]
Post subject: 
Quote:
Calibrate the 0-1" to 0

Then measure the 1" calibration with the 0-1" mic

If it's 1", calibrate the 1-2" with the 1" calibrator

If it's not 1" calibrate the 1-2" to whatever the 1" calibrator actually is (i.e .999 1.0001 whatever)

Now you have the 0-1 and 1-2 calibrated.

Measure the 2" calibrator with the 1-2 mic and do the above to get the 2-3" mic calibrated...........

Good sound advice !!

Richard
Author:  Eatkinson [ Tue Apr 30, 2013 7:21 pm ]
Post subject: 
Thanks. So I guess I need to work on learning to read my micrometers. Glad to know the mains all still in spec: figured, but couldn't quite tell. Got to do the same thing on the cam. The connecting rod journals I'm probably going to have to have ground because #6 spun. But I'll still going to measure it to be sure.

I wonder how I read it wrong.... Watched a few tutorials online about how to read these, but kept coming up with the same measurements....
Author:  Sprag [ Tue Apr 30, 2013 7:29 pm ]
Post subject: 
Quote:
All but the last one are around 2.7495 which I see as 2.7513
That's how I'm seeing it too.
Quote:
Quote:
Calibrate the 0-1" to 0
Then measure the 1" calibration with the 0-1" mic
If it's 1", calibrate the 1-2" with the 1" calibrator
If it's not 1" calibrate the 1-2" to whatever the 1" calibrator actually is (i.e .999 1.0001 whatever)
Now you have the 0-1 and 1-2 calibrated.
Measure the 2" calibrator with the 1-2 mic and do the above to get the 2-3" mic calibrated...........
Good sound advice !!

Richard

Agreed, great advice!
Author:  Fopar [ Tue Apr 30, 2013 7:35 pm ]
Post subject: 
Having the whole crank turned is the best insurance for the money, juat be sure to run something like a gun cleaning rod with a patch on it through the oil pasages after it's ground same with the block if you have any work done on it or just for general principles.

Richard
Author:  DusterIdiot [ Tue Apr 30, 2013 7:37 pm ]
Post subject:  Looks good...
Quote:
Got to do the same thing on the cam.
That will be good practice, but if your machinist is hot tanking the block for cleanup before magnaflux and overboring, he will remove the cam bearings (they get chewed up by the hot tank) then toss them and install a new set (if you are ordering a kit he will just install those).

If everything is within spec you can go standard bearings on those. (I might be inclined to spend a few more moments shining the 'fat' journal with the 500 grit to see if it comes down a little more).

Mic the rod journals and see where they land, if the spun bearing journal isn't too badly scored/burned/ out of round, then you might be able to go .010 on them, if the machinist makes a mistake it might go .020...

-D.Idiot
Author:  emsvitil [ Wed May 01, 2013 2:07 am ]
Post subject: 
Also use the 0-1 to get the feel for repeatable measurements (i.e. 0 )
Author:  CNC-Dude [ Wed May 01, 2013 10:05 am ]
Post subject: 
Also, when you take your crank to the machine shop, take your mic with you also and get them to check it against their mic and standard. Then let the machinist mic a crank they already have reground with your mic and then you mic the same crank and see how much difference there is between the reading you get and he gets with the same mic.
Author:  Eatkinson [ Wed May 01, 2013 9:01 pm ]
Post subject: 
Thanks for the thoughts all. The guidance helped. Crank is mic'd. Now, on to the machine shop.
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