Measuring

340wedge

Newly Enlightened
Joined
May 22, 2011
Messages
60
Location
IN
I haven't seen this come up yet so I figured its about time for it. I'm hoping others will chime in to share their knowledge.

First off I'm no expert machinist so take it with a grain of salt. :)

Nothing has made me chase my own tail in machining more than not having decent ways to accurately measure, whether tools or methods.
My main tool for most noncritical measurements is a set of 6" Etalon dial calipers. They are not cheap new but if your lucky you can nab them on the well known auction site for pretty cheap. They are not a well known brand which helps a lot but they are still Swiss made.

For depth measurements I prefer Brown and Sharpe depth mics. Kind of hard to get the feel of them at first but with practice its not hard to pick up. Reading them also takes some practice since its backwards from a normal micrometer. Again they can be found at a good price on the auction site if you are patient.

I prefer Etalon micrometers for critical measurements. They are easy to take apart and clean or adjust if need be. I get more consistent readings with them than other brands.

Inside measurements took me the longest to measure accurately. I started with the normal telescoping gauge sets and the split ball but never was able to get really good measurements. I couldn't afford a pin gauge library so that was out of the question. I ended up getting a mitutoyo (145-193) ID micrometer and very happy with the results. I still use telescoping gauges set with a micrometer to check for bore taper.

Dial height gauge has been a very big help for measuring and or scribing just about anything along with a cheaper granite surface block.

Thread gauges, whether cheap or expensive I can not tell the difference between them. I use them only to get the tpi.

Lastly one area where its a bad idea to skimp on the cost is a set of gage blocks. You can again get lucky on the auction site just make sure to take them or send them out to get calibrated. You can then check out all your tools using them to know if they are accurate or not instead of buying new and hoping they are. Also you can use them to practice with to make sure you are measuring right.


Opps forgot a tip, if you hunting for used tools. If there is a sticker on it that says for "reference only" that means the tool failed to meet calibration.
 

Jumpmaster

Flashlight Enthusiast
Joined
Jun 14, 2001
Messages
1,641
Location
Friggin' MORE COWBELL!!!
I have a Starrett model 230 micrometer that I bought for $10 and am going to buy the 1"-2" model at a different shop for $10 when I am back home.

Ahhhhhhhh...fun with metrology. :)
 

will

Flashlight Enthusiast
Joined
Apr 14, 2004
Messages
2,597
Measuring anything requires a certain 'touch' or 'feel' to get it right. It is best to practice on something that is a known size, like gauge blocks. A lot of tools have a friction knob that does not allow you to over tighten the tool. Like anything you do in life - the more you do it, the better you get at it ( providing you are doing it correctly in the first place )
 

justanotherguy

Enlightened
Joined
Sep 8, 2008
Messages
515
I haven't seen this come up yet so I figured its about time for it. I'm hoping others will chime in to share their knowledge.

First off I'm no expert machinist so take it with a grain of salt. :)

Nothing has made me chase my own tail in machining more than not having decent ways to accurately measure, whether tools or methods.
My main tool for most noncritical measurements is a set of 6" Etalon dial calipers. They are not cheap new but if your lucky you can nab them on the well known auction site for pretty cheap. They are not a well known brand which helps a lot but they are still Swiss made.

For depth measurements I prefer Brown and Sharpe depth mics. Kind of hard to get the feel of them at first but with practice its not hard to pick up. Reading them also takes some practice since its backwards from a normal micrometer. Again they can be found at a good price on the auction site if you are patient.

I prefer Etalon micrometers for critical measurements. They are easy to take apart and clean or adjust if need be. I get more consistent readings with them than other brands.

Inside measurements took me the longest to measure accurately. I started with the normal telescoping gauge sets and the split ball but never was able to get really good measurements. I couldn't afford a pin gauge library so that was out of the question. I ended up getting a mitutoyo (145-193) ID micrometer and very happy with the results. I still use telescoping gauges set with a micrometer to check for bore taper.

Dial height gauge has been a very big help for measuring and or scribing just about anything along with a cheaper granite surface block.

Thread gauges, whether cheap or expensive I can not tell the difference between them. I use them only to get the tpi.

Lastly one area where its a bad idea to skimp on the cost is a set of gage blocks. You can again get lucky on the auction site just make sure to take them or send them out to get calibrated. You can then check out all your tools using them to know if they are accurate or not instead of buying new and hoping they are. Also you can use them to practice with to make sure you are measuring right.


Opps forgot a tip, if you hunting for used tools. If there is a sticker on it that says for "reference only" that means the tool failed to meet calibration.

I would not automatically assume a tool failed to meet calibration... I've worked in places that had the tools cert'ed.... and those that couldn't be done that day or came in later were labeled 'reference only'.
It wasn't something about the tool that was known to be inaccurate, rather the tool had not been tested and was not in the database....Therefore it was not certified and for official purposes could not be used to taking measurements...
.02" added
 
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