Measuring with a Micrometer
Discussion
I picked this up on the Sunday market but I'm unsure how to measure with it.
5 tenths would be 0.5" (500 thou) ?
plus 2 divisions would be 0.040" (40 thou)?
plus thimble reading, 12 thou, plus 2x 4 ten thous (0.0008) ?
So how would this be written in inches ? 0.5528" ?
A little bit confusing for me,
5 tenths would be 0.5" (500 thou) ?
plus 2 divisions would be 0.040" (40 thou)?
plus thimble reading, 12 thou, plus 2x 4 ten thous (0.0008) ?
So how would this be written in inches ? 0.5528" ?
A little bit confusing for me,
These dual reading mics came out in the early seventies but never truly
took off.
Yes the correct reading is 0.5528". The fun starts with the metric reading
as the Zero datum line is on a spiral in red which wraps around the barrel
reading in whole mm's. Around the thimble are the tenths and hundredths.
The theory was a 50 TPI thread giving 20 thou divisions. This was very close to
19 and a bit thous for 1/2 mm. So to make it read correct the spiral datum line
came into play correcting the accrued error.
My job at the time was a machine shop training instructor and saw more scrapped
work due to misreading than was necessary.
took off.
Yes the correct reading is 0.5528". The fun starts with the metric reading
as the Zero datum line is on a spiral in red which wraps around the barrel
reading in whole mm's. Around the thimble are the tenths and hundredths.
The theory was a 50 TPI thread giving 20 thou divisions. This was very close to
19 and a bit thous for 1/2 mm. So to make it read correct the spiral datum line
came into play correcting the accrued error.
My job at the time was a machine shop training instructor and saw more scrapped
work due to misreading than was necessary.
Evoluzione said:
honestbob said:
My job at the time was a machine shop training instructor and saw more scrapped
work due to misreading than was necessary.
Just use a digital, if you get it wrong with one of those you need serious help!work due to misreading than was necessary.
was a doctors finger up your jacksie checking out your prostate.
It's made by Moore and wright,
Patent No: GB595016
595,016. Gauging-devices. MOORE & WRIGHT (SHEFFIELD), Ltd., and MORRISON, A. E. March 28, 1945, No. 7827. [Class 83 (iii)] [Also in Group XIX] A micrometer device has a screw-threaded spindle which is rotated by means of a drum provided with Braille graduations on its periphery which co-operate with a datum mark, perceptible by touch, on a stationary member adjacent to the drum. In a machine tool slide, a base 51 carries a slide 54 which is engaged and traversed by a nut 55 on a feed screw 50, on which are mounted three drums 16, 17, 18. The drum 18 is secured to the screw 50 and the drum 17 is held against rotation by means of a bracket 52. The drums 16 and 17 have toothed inner peripheries engaged by two planet wheels carried by a spindle mounted in a bearing formed as a radial extension of a sleeve secured to the screw 50 and, in this manner, the drum 16 is caused to rotate, for example, one-fortieth of a revolution for each complete revolution of the drum 18. Raised graduations on the peripheries of the drums 16 and 18, on which the zero marks are preferably raised lines, cooperate with a raised datum line on the centre stationary drum 17, which is also provided with a set of vernier graduations. The drums 16 and 18 have forty and twenty-five graduations indicated by Braille characters respectively, those on the drum 16 being indicated in ten groups of four and those on the drum 18 in five groups of five. A micrometer and a micrometer comparator (see Group XIX) incorporating the device are also described.
http://worldwide.espacenet.com/publicationDetails/...
Patent No: GB595016
595,016. Gauging-devices. MOORE & WRIGHT (SHEFFIELD), Ltd., and MORRISON, A. E. March 28, 1945, No. 7827. [Class 83 (iii)] [Also in Group XIX] A micrometer device has a screw-threaded spindle which is rotated by means of a drum provided with Braille graduations on its periphery which co-operate with a datum mark, perceptible by touch, on a stationary member adjacent to the drum. In a machine tool slide, a base 51 carries a slide 54 which is engaged and traversed by a nut 55 on a feed screw 50, on which are mounted three drums 16, 17, 18. The drum 18 is secured to the screw 50 and the drum 17 is held against rotation by means of a bracket 52. The drums 16 and 17 have toothed inner peripheries engaged by two planet wheels carried by a spindle mounted in a bearing formed as a radial extension of a sleeve secured to the screw 50 and, in this manner, the drum 16 is caused to rotate, for example, one-fortieth of a revolution for each complete revolution of the drum 18. Raised graduations on the peripheries of the drums 16 and 18, on which the zero marks are preferably raised lines, cooperate with a raised datum line on the centre stationary drum 17, which is also provided with a set of vernier graduations. The drums 16 and 18 have forty and twenty-five graduations indicated by Braille characters respectively, those on the drum 16 being indicated in ten groups of four and those on the drum 18 in five groups of five. A micrometer and a micrometer comparator (see Group XIX) incorporating the device are also described.
http://worldwide.espacenet.com/publicationDetails/...
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