Rick your probably getting tired of hearing from me. But your test is not a valid test, it not a real world application of this tool. I've been in pattermaking near all my life and in inspection using real world application of this and other measuring tools. Right now I program coordinante measuring machines. Basicly a 5 axis cnc that measures machined parts. The CMM is not as accurate as the calipers you have discribed in you article. Using those inside and outside calipers you will be lucky to get within .015, I have mititoyo vernier calipers that will read to 1/128" or .0075" you'll never get to that in a real world application with manual calipers. These tools are to be used with a rule, fractional or decimal, by compairing them to a known value and saying you can get that accurate in incorrect, although you may get lucky. a simple test would be to bore a 2" diameter using just the inside caliper to get to 2", the using just the outside caliper and
without checking the fit, until completed, turn a piston to fit leaving a .005" over all clearance. Don't check the measurment with anything but a rule. This will give you an idea of the accuracy of these tools. another test would be to turn/cut several parts to a given dimension the measure the repeatablity of your use of the tools. These are eyeball tools at best, using a rule and calipers.
Dave Patterson
odd_kins@yahoo.com
http://home.comcast.net/~oddkins/foundry_home.html
--- On Mon, 1/31/11, Rick Sparber <rgsparber@aol.com> wrote:
From: Rick Sparber <rgsparber@aol.com>
Subject: [gingery_machines] new article: The Intersection of Art and Precision (Using a Caliper)
To: valleymetal@yahoogroups.com, mill_drill@yahoogroups.com, gingery_machines@yahoogroups.com
Date: Monday, January 31, 2011, 4:02 PM
Developing the proper "feel" when using a mic or caliper is essential to
accuracy. This article presents a few exercises that will help you develop
and keep this feel. Although written for someone new to the metal working
hobby, I welcome experienced machinists to read it too and send me comments.
This is the only way I will reduce mistakes plus add new insights. All of us
are smarter than any one of us.
If you are interested, see
http://rick.sparber.org/f.pdf
Rick
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
http://groups.yahoo.com/group/gingery_machines/app/peoplemap/view/map
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