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the Truth about Feeler Gauges!!??

oley55

This may not be news to the machinist types out their, but today I discovered those fan feeler gauge sets are not what I expected. I was contemplating using a cut piece of .003" feeler gauge under a GO gauge to measure for NO-GO. I have a 30+ year old USA made (no name and rust free) 25 gauge set. I measured the first three with a micrometer and got these results; .002"=.0036", .003"=.0052", .004"=.0040". I stopped measuring at this point.

I only mention it here since some folks use feeler gauge material for shims in their shell holders and may not be getting the shim amount expected.
 
rsmithsr50 said:
may I suggest you check your mic ??
Click to expand...

got similar measurements (though not as accurate) on my calipers. Besides, if my Vernier mic were screwing up I wouldn't be able to get the same results over and over. Did you note I measured the .004" gauge at .0040"?

I found a review on Amazon for a set of feeler gauges and the guy had similar issues (mislabel gauges) but those were Chinesium. And here's a link to Precision Brand gauges with an example of a competitors gauges causing a costly manufacturing snafu. https://precisionbrand.com/faq/feeler-gage-questions/
 
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oley55 said:
This may not be news to the machinist types out their, but today I discovered those fan feeler gauge sets are not what I expected. I was contemplating using a cut piece of .003" feeler gauge under a GO gauge to measure for NO-GO. I have a 30+ year old USA made (no name and rust free) 25 gauge set. I measured the first three with a micrometer and got these results; .002"=.0036", .003"=.0052", .004"=.0040". I stopped measuring at this point.

I only mention it here since some folks use feeler gauge material for shims in their shell holders and may not be getting the shim amount expected.
Click to expand...
Are they kinked at all? If you measure on a bend you'll get a thick reading.
 
oley55 said:
This may not be news to the machinist types out their, but today I discovered those fan feeler gauge sets are not what I expected. I was contemplating using a cut piece of .003" feeler gauge under a GO gauge to measure for NO-GO. I have a 30+ year old USA made (no name and rust free) 25 gauge set. I measured the first three with a micrometer and got these results; .002"=.0036", .003"=.0052", .004"=.0040". I stopped measuring at this point.

I only mention it here since some folks use feeler gauge material for shims in their shell holders and may not be getting the shim amount expected.
Click to expand...

Can you post a pic? They sound like automotive spark plug/points gapping feelers.
 
Dusty Stevens said:
Unless you use a mic every day in your job for many years youll find all kinds of things that dont measure right and they change every day
Click to expand...
I worked as a machinist throughout the '80s and '90s, running centerless grinders, blanchard grinders and various other surface grinders, mills and lathes. These were manual machines from the '30s through the '60s, never designed for usage into the realm of .0001". By constantly using calibration blocks, keeping the mic and materials clean, I was able to regularly hold +/- .00025 or better. It took a lot of practice and patience to achieve this. On my finish passes I ran the pieces numerous times with no adjustment to achieve this precision. I measured literally 100s or more pieces per day for about 20 years. Quality control checked my work constantly and passed it. It takes awhile, but does come about. It is not the price of the micrometer, but rather using the same tool everyday. I then used and still use a noname Polish made mic as well as the name brand items. With a lot of practice, you can make a calibration block read the same, while your eyes are closed, in other words, .0001 readings are possible with a micrometer. Calipers are only good for rough measurements, never a finish dimension!
For what it is worth, we made parts for the ISS for Boeing in Huntsville, Alabama, before anyone had herd of the ISS. It is still up there.
A TIP: When using a micrometer, using the space between buttons on the front of your shirt, lightly close the mic and pull it up and down to clean it. Then take your measurement. Also, use calibration blocks on a regular basis that are very close to your final measurement. They will let you know when to adjust your mic for a .0001 plus or minus adjustment.
 
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jimcasey01 said:
I worked as a machinist throughout the '80s and '90s, running centerless grinders, blanchard grinders and various other surface grinders, mills and lathes. These were manual machines from the '30s through the '60s, never designed for usage into the realm of .0001". By constantly using calibration blocks, keeping the mic and materials clean, I was able to regularly hold +/- .00025 or better. It took a lot of practice and patience to achieve this. On my finish passes I ran the pieces numerous times with no adjustment to achieve this precision. I measured literally 100s or more pieces per day for about 20 years. Quality control checked my work constantly and passed it. It takes awhile, but does come about. It is not the price of the micrometer, but rather using the same tool everyday. I then used and still use a noname Polish made mic as well as the name brand items. With a lot of practice, you can make a calibration block read the same, while your eyes are closed, in other words, .0001 readings are possible with a micrometer. Calipers are only good for rough measurements, never a finish dimension!
For what it is worth, we made parts for the ISS for Boeing in Huntsville, Alabama, before anyone had herd of the ISS. It is still up there.
A TIP: When using a micrometer, using the space between buttons on the front of your shirt, lightly close the mic and pull it up and down to clean it. Then take your measurement. Also, use calibration blocks on a regular basis that are very close to your final measurement. They will let you know when to adjust your mic for a .0001 plus or minus adjustment.
Click to expand...
alot of good info there- Thanks much for that.
 
Spent my life as a toolmaker, When I really wanted to work that small and it was possible, I used a granite surface plate, height gauge, 10ths indicator, and gauge blocks, for that type of inspection. One fellows 10th was another persons 2 10ths. Rarely worked that close, but did do a little tool grinding where the optical comparator was the measuring tool of choice. With out practice, the skill of measuring that close with the human body is iffy at best. The next day some fellow with a German plainner (file) will undo all of your hard work.
As the name implies (feeler gauges), it is all in the touch.



Setting valves on a solid lifter cam does not do them any favors (feeler gauges).
 
Mic backlash for the first couple thou.

Try the 0.002 Plus a 0.004.
What do you get?

The 0.003 reading thicker than the 0.004 is a bad sign :)
 
Taught technical education for many years ( aircraft engine overhaul).
Having students reliably use a micrometer or caliper was a learning challenge. I always smile when there is a discussion about home machining to tolerances of .0001". No doubt, some may be capable of that but what level of accuracy is the machine they are using capable of?
Keep ur measuring tools clean and at correct temperatures for accuracy.
Great suggestion to check ur mic's for zero.
 
Temperature, good equipment, and skill using good equipment are needed. Another part of the equation is what your measuring, your not going to measure to a tenth on a 50RA turned surface.
 
Just for kicks and grins I checked mine that say they were made by the Chinesium company. the .002, .003, .004, and .005 all read on size. The worst one was the .002 which read .0002 large. These measurements were done in a 60 degree garage but the effect of temperature on something .005 thick will be minimal.

I would suggest throwing them away buy a new set and check them.
 
Gappmast said:
Just for kicks and grins I checked mine that say they were made by the Chinesium company. the .002, .003, .004, and .005 all read on size. The worst one was the .002 which read .0002 large. These measurements were done in a 60 degree garage but the effect of temperature on something .005 thick will be minimal.

I would suggest throwing them away buy a new set and check them.
Click to expand...

Or throw the mic away...

OP Can you post a picture of your micrometer?
 
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