General Tools 102 0-Inch to 1-Inch .001-Inch Graduation Micrometer

All specs meet my standards. Good value for price. Retired Master Mechanic.

Zeroes consistently and produced reasonable and consistent readings on ball bearings I had lying around. This was way nicer than I expected for a cheap tool. Mine came perfectly zeroed.

The instructions provided for alignment are useless, so I am including corrected instructions. First though is the anatomy in the terms used by General Tools where available, going from left to right when frame and anvil are on the left. 1 Frame, 2 Anvil (stationary measurement surface), 3 Spindle (movable rod with measurement surface), 4 Lock, 5 Barrel (stationary sleeve with numbers and graduation lines), 6 Thimble (rotates to adjust spindle position) 7 Ratchet Knob (used for final closure of spindle to anvil or surface of measured object)Calibration Procedure.Fully open the lock. Back off the thimble until you can see the slotted-head setscrew on the barrel. Loosen the setscrew 1/8th to 1/4th turn with a 2mm flat-blade screwdriver (jeweler’s screwdriver). Slowly close the spindle onto the anvil using the ratchet knob until you get three clicks. Use the larger section of the supplied pin spanner wrench to turn the barrel until the horizontal mark on the barrel matches the "0" mark on the thimble. Back off the thimble again to reveal the setscrew on the barrel, and tighten it.Initial CalibrationIt appears that General Instruments Micrometer is not initially calibrated. The two I checked were both reading about 1.5 mils when the reading should have been zero. On one the setscrew on the barrel had not been tightened.How to Read the MicrometerFor simple description, I will use units of mils (one mil is one thousandth of an inch, 0.001”). To convert from mils to inches, divide the number of mils by 1000. Each major (numbered) graduation on the barrel equals one hundred mils (.100”). Each minor (un-numbered) graduation line on the barrel equals twenty five mils (.025”). Each major graduation line on the thimble equals one mil (.001”); minor graduations are ½ mil (.0005”).For easy reading in mils (thousandths of an inch), do the following. Take the product of 100 times the number of the highest visible major graduation line on the barrel, and add the product of 25 times the number of minor graduation lines between the major one and the thimble. Then add the number of the major thimble graduation line which coincides with the horizontal line of barrel. Note that special care is required when either the major or miner graduation line of the barrel is just visible at the edge of the thimble. For example, if the thimble reads 20, the barrel line just visible at the thimble edge should NOT BE read or counted, because it will not be valid until a thimble reading of 0 past the present barrel line (same as 25 past the previous barrel line) has been reached.Accuracy Error Due to FrictionIf the frictional torque is a significant percentage of the torque provided by turning of the ratchet knob, either the calibration will be non-repeatable and thus inaccurate, or some measurement distances might produce non-repeatable and thus inaccurate results or both. The first instrument I had was shipped without adequate protection in a large container with two heaver, unrestrained items. The micrometer had escaped from its blister pack, and I assume taken a beating. It had several distances that had enough friction to cause ratcheting as the ratchet knob was turned. When that happens, measurement to one mil accuracy is not possible. Cleaning the threads gave some improvement, but still, checking the calibration would result in a variation of typically 1.5 mils. I exchanged it.The next micrometer was shipped in a standard shipping envelope with a very thin layer of bubble padding on the inside of the envelope. This packaging might provide some protection from the shock of dropping or throwing the package but none from the pressure of other objects pressing against it. This micrometer arrived with the thimble rubbing against the barrel. That caused the ratchet to click at several locations. I was able to correct the misalignment of the thimble by careful correction using only my fingers. This micrometer now repeats the calibration check within 1/4th of a mil. This instrument is likely to meet the specified accuracy of 1 mil.As received, both this instrument and the first one had so much friction as to render the ratchet knob useless. Using only the thimble for closing the spindle might have achieved an accuracy of two or three mils. The fact that I was able to correct the misaligned thimble problem with moderate finger pressure is an indication of the vulnerability of this instrument to shipping stresses. The blister pack is not appropriate protection to guarantee this instrument will be capable of one mil accuracy after shipping and handling.CosmeticsOn the micrometer I have, the threaded holes for mounting the plastic plates each side of the frame are poorly located and apparently angled. The plastic plates are both off-center, but one is so far off that it extends past the frame. I don’t think this problem was as bad on the first micrometer I checked.

great, quality product

I was concerned about buying an inexpensive micrometer, but this one works perfectly for my needs. Easy to read and use.

I wanted this to gauge my guitar strings. It is made of steel and seems to be very sturdy. It came set to zero, but also has a tool to recalibrate if needed. I looked in local hardware stores for this instrument, but only found one that was plastic and cheaply made ( at almost three times the price I paid for this one) Well worth the money. I didn't like how it was shipped. It was shipped in a bubble wrap envelope. I would think they would ship this in a small box with bubble wrap. The packaging that the micrometer is sold in kept it from any damage. If a heavy box was tossed on it, damage could occur.

Bought this to help my son learn to use micrometers. Easy to learn on and very accurate.

The General Tools Number 102 (analog) Micrometer is a handy tool to have around the house if you need to make precision measurements of external dimensions up to 1 inch in size.It is well made (the screw mechanism has a nice smooth feel) and the only exception that I have to report is that the calibration instructions (on the paper backside of the plastic cover that the micrometer comes in) are misleading as they refer to a previous (slightly different) mechanical design (I spoke with a General Tools' Engineer and this is what he told me). Instead of a 'hex tool' being needed to loosen the base ring (my term) on the micrometer (to allow the zero adjustment to be shifted) a small flat blade screwdriver is needed. In addition (the instructions say nothing about this) the screw (to loosen for the zero adjustment calibration) isn't visible until you back-off the adjusting 'thimble' (that you turn when making measurements) a couple of tenths of an inch.Like any precision device the micrometer needs to be treated gently (i.e. don't toss it unprotected into your toolbox with screwdrivers and wrenches). If you open the package carefully (it's only secured with a couple of heavy staples) it can be reused for storing the micrometer in.

Presition

Se siente de buena calidad y es bastante preciso para el precio, la verdad me gustó mucho, habría que ver que tan duradero es.

De calidad, fácil de usar y practico, hubiese estado increíble un estuche

Works well and seems to be decent quality.

Buen producto, le falta calidad