villaveloframes
Tool of the week: Micrometer
Calipers are rather effective in quickly measuring the distance between surfaces. However, however to be very accurate the micrometer comes in handy.
The measurement components of a micrometer are very accurately ground. The fixed side is called the anvil and one edge of the object being measured sits against it. The main measuring part of the tool, called the spindle, is turned towards the object via the thimble, which moves down a sleeve containing the measurement markings. As the spindle comes into contact with the object, a ratcheting screw on the end of the thimble is turned until it clicks, signifying that the spindle has contacted the surface of the object and does not need to be tightened any further as that will result in an inaccurate measurement.
To read the micrometer, as pictured below we are measuring the diameter of the fork steerer at the crown, where the headset's crown race is fitted. The inner sleeve of the thimble reads out millimeters in half millimeter increments, with the upper markings denoting the half millimeters. The outer thimble reads out 1/100ths of a millimeter (0.01mm).
So, what does the diameter read?
The inner thimble goes past the two lower markings and the upper two also. And the outer thimble reads 10. That gives us:
The inne thimble goes past the two lower markings and the upper two also. And the outer thimble reads 10. That gives us:
26.0 (lower inner thimble marking) + 0.5 (upper inner thimble marking) + 0.1 (outer thimble marking reads 10 x 0.01) = 26.6mm
As most crown race sizes for 1 inch headsets are 26.4mm (with the exception of JIS using 27mm), this fork's diameter of 26.6mm is an appropriate size for a tight interference fit.
We will use the micrometer often for framebuilding, especially fork work. With our lathe we can turn down the diameter at the crown if it is too large to properly fit the headset race, so the micrometer will be used to check the diameter of the crown race seat.
You have seen before the micrometer was used to check the diameter of our adjustable reamer was set properly before reaming the seat tube of Quang's Kenevans: www.facebook.com/villaveloframes/posts/1885813825026288
Micrometers are also very useful for accurately measuring seatpost and handlebar diameters, for measurements such as the old Cinelli standard of 26.4mm or small increments in seatpost size, e.g. 27.0 and 27.2mm seatposts.
Tool of the week: Micrometer
Calipers are rather effective in quickly measuring the distance between surfaces. However, however to be very accurate the micrometer comes in handy.
The measurement components of a micrometer are very accurately ground. The fixed side is called the anvil and one edge of the object being measured sits against it. The main measuring part of the tool, called the spindle, is turned towards the object via the thimble, which moves down a sleeve containing the measurement markings. As the spindle comes into contact with the object, a ratcheting screw on the end of the thimble is turned until it clicks, signifying that the spindle has contacted the surface of the object and does not need to be tightened any further as that will result in an inaccurate measurement.
To read the micrometer, as pictured below we are measuring the diameter of the fork steerer at the crown, where the headset's crown race is fitted. The inner sleeve of the thimble reads out millimeters in half millimeter increments, with the upper markings denoting the half millimeters. The outer thimble reads out 1/100ths of a millimeter (0.01mm).
So, what does the diameter read?
The inner thimble goes past the two lower markings and the upper two also. And the outer thimble reads 10. That gives us:
The inne thimble goes past the two lower markings and the upper two also. And the outer thimble reads 10. That gives us:
26.0 (lower inner thimble marking) + 0.5 (upper inner thimble marking) + 0.1 (outer thimble marking reads 10 x 0.01) = 26.6mm
As most crown race sizes for 1 inch headsets are 26.4mm (with the exception of JIS using 27mm), this fork's diameter of 26.6mm is an appropriate size for a tight interference fit.
We will use the micrometer often for framebuilding, especially fork work. With our lathe we can turn down the diameter at the crown if it is too large to properly fit the headset race, so the micrometer will be used to check the diameter of the crown race seat.
You have seen before the micrometer was used to check the diameter of our adjustable reamer was set properly before reaming the seat tube of Quang's Kenevans: www.facebook.com/villaveloframes/posts/1885813825026288
Micrometers are also very useful for accurately measuring seatpost and handlebar diameters, for measurements such as the old Cinelli standard of 26.4mm or small increments in seatpost size, e.g. 27.0 and 27.2mm seatposts.