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Starting to get a feel for this stuff. Nessism your posted video was a big help. The 10 thou micrometer arrived yesterday. Silky smooth and just needed a small tweak on the barrel/sleeve to zero it. Even with what I think is a worn sloppy telescoping gauge I’ve been able to “feel” the ID dimension and get very consistent repeatable numbers. I’m playing with the piston pin hole and the wrist pin. Then a set the mic on a .675 and used it to set the telescope gauge. Then backed off the mic and sized the telescope gauge. I’ve done this several time and can get very repeatable measurements. As soon as the other set is telescope gauges arrive I’ll break the crank free of its shipping package and dive in… 

Good on you Matt!  Nothing like being able to measure stuff on your own and get good repeatable results.  Measuring to one thou is pretty easy after you practice for a while and get good at it.  Measuring to 10/thou is a bit more difficult and where you really need a feel for what you are doing.  A lot of guys rely on the rachet stop for telling them tight enough.  I choose to use the large thimble barrel and let my fingers tell my brain when it's tight enough.  Rachet stops can sometimes give you false readings.  If you know someone who is well versed in measuring things using mic's and telescoping gages etc., have them test your skills at measuring items and see how you do.  Don't be surprised though if the readings are slightly different especially measuring to 10/thou, hence in many instances there will be a "+ or - " tolerance in readings even at a 1/thou threshold.  I have a pretty good DRO on my mill that measures to 4 decimal places and even that can give you different readings at times.  It's weird and depends on how the sun and moon align.

Rick H.

Thanks Rick. Great idea. I will have to buddy up with a machinist and challenge him to a mic off….

Competition breeds perfection!

Rick H.

Seams I’m going to be in the market for a crankshaft…   

Well that sucks!  Maybe only new rods?

Yeah!! Great measuring tools turn a disassembly and reinstall into looking for new parts and waiting for delivery really fast!! Now you'll see what you have been missing!! Good Luck! Chris

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Well that sucks!  Maybe only new rods?

HRM, new (used) rods are out of the budget, I’ve been ballparked $500 minimum. Though I’m going to reach out to both Gardner and Pearson about my options. Allen Millyard makes pressing the crank together pretty easy. 

It's better knowing the true situation before "saving" money and installing them in that condition.  Accurate measuring is a double edged sword.  Sometimes it does not reward you for being accurate!  But in the long run the reward will come when you know it went back together within specification.

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It's better knowing the true situation before "saving" money and installing them in that condition.  Accurate measuring is a double edged sword.  Sometimes it does not reward you for being accurate!  But in the long run the reward will come when you know it went back together within specification.

True, Thanks. I had previously seen the spec range but hadn’t committed them to memory. I didnt look them up the evening I started to mic the crank. I wanted to just get the measurements as is without skewing the results hoping it would be within spec. Like said it’s actually a money saver in the long run. If I had assembled as is it could have damaged the engine, and all the work put into it. 

 

That YouTube video of telescoping gauge method of snugging up the gauge and gently pulling it through the diameter of the round hole is exactly correct, that way the thumb screw is not disturbed when the gauge is at the correct orientation to yield an accurate reading. The other thing he does is rely on the friction clutch built into the thimble on the micrometer. This helps with consistent readings since the user is not relying on “feel”. The feel is set in the friction clutch. 
I have my grandfathers Starret 0” to 1” micrometer, it’s pretty old (75 years plus?) and works perfectly, the clutch gives exact readings. 
The more you practice the better you will be at it. 
 

MauiZ1, thanks for the tip. I’ll be getting more practice soon. A member has sold me a Crankshaft so I’ll be breaking out the tools soon. Stay tuned and wish me luck I find a good part.