Cheap tool alert - 4in Digital Calipers
American Science and Surplus' latest catalog has a 4" digital caliper for about $15US. I could not resist the temptation, as I've been looking for a small digital caliper to keep in my small toolbox in my office at work.
The caliper is made in China, according to the box, but there is no manufacturer's name. The construction is completely plastic and feels a bit flimsy, but should hold up with care. The plastic construction is an advantage in that the caliper is very light, which is nice if your toolbox is already on the heavy side. The moving blade head has noticable wobble, but less than the resolution of 0.01". The moving head slides smoothly on the beam. Overall length is 7". The outside measurement blade depth is about 1-3/16", and the inside measurement blade depth is 1/2". Unlike most calipers, there is no depth measurement pin. There is also no locking mechanism.
With a display digit height of 3/8" and good contrast, measurements are easy to read. The display is a little slow to update while the head is in motion, but not objectionably. Three color-coded buttons control the OFF, ON and ZERO functions. The ON button is also used to toggle between inch and millimeter measurement. There is no tactile click to the buttons but they are easy to operate, regardless.
The resolution is only 0.01" and 0.1mm which is less than the more typical resolution of 0.001". I checked the accuracy against my Mitutoyo CD-6CS calipers, and measurements are consistently low across the range by 0.01", which isn't bad. The indicated metric measurement matches the inch measurement to the displayed resolution. Using the metric indication gives you more than twice the resolution (0.01" vs. 0.004"), but the error on the metric scale is still about 0.01" low.
The caliper is powered by an SR44 watch battery, which is included. The caliper will automatically power-down after a few minutes of inactivity. Remember to re-zero the caliper after changing the battery, because it seems to power up with a random offset. In fact, it is a good idea to check the zero frequently, because I noticed an occasional offset of about 0.2" had occurred.
If you don't already have a caliper, I can't really recommend this one for general purpose use. The limited range, low resolution, lack of a depth pin and occasional random offsets all mean that your money would be better put towards a better 6" caliper. However, if, like me, you just need a spare to keep in a satellite toolbox, this one will do the job. It will also be less heartbreaking if someone walks off with this caliper than your $150 'good one'. This caliper would certainly be better than nothing if you are on a tight tool budget.
At this price, this would be a good caliper for hacking applications, if you need to build a displacement measurement display into a fixture or instrument. I haven't had it apart, but it might be possible to tap into the circuit to transmit the measurement to another instrument.
The caliper is made in China, according to the box, but there is no manufacturer's name. The construction is completely plastic and feels a bit flimsy, but should hold up with care. The plastic construction is an advantage in that the caliper is very light, which is nice if your toolbox is already on the heavy side. The moving blade head has noticable wobble, but less than the resolution of 0.01". The moving head slides smoothly on the beam. Overall length is 7". The outside measurement blade depth is about 1-3/16", and the inside measurement blade depth is 1/2". Unlike most calipers, there is no depth measurement pin. There is also no locking mechanism.
With a display digit height of 3/8" and good contrast, measurements are easy to read. The display is a little slow to update while the head is in motion, but not objectionably. Three color-coded buttons control the OFF, ON and ZERO functions. The ON button is also used to toggle between inch and millimeter measurement. There is no tactile click to the buttons but they are easy to operate, regardless.
The resolution is only 0.01" and 0.1mm which is less than the more typical resolution of 0.001". I checked the accuracy against my Mitutoyo CD-6CS calipers, and measurements are consistently low across the range by 0.01", which isn't bad. The indicated metric measurement matches the inch measurement to the displayed resolution. Using the metric indication gives you more than twice the resolution (0.01" vs. 0.004"), but the error on the metric scale is still about 0.01" low.
The caliper is powered by an SR44 watch battery, which is included. The caliper will automatically power-down after a few minutes of inactivity. Remember to re-zero the caliper after changing the battery, because it seems to power up with a random offset. In fact, it is a good idea to check the zero frequently, because I noticed an occasional offset of about 0.2" had occurred.
If you don't already have a caliper, I can't really recommend this one for general purpose use. The limited range, low resolution, lack of a depth pin and occasional random offsets all mean that your money would be better put towards a better 6" caliper. However, if, like me, you just need a spare to keep in a satellite toolbox, this one will do the job. It will also be less heartbreaking if someone walks off with this caliper than your $150 'good one'. This caliper would certainly be better than nothing if you are on a tight tool budget.
At this price, this would be a good caliper for hacking applications, if you need to build a displacement measurement display into a fixture or instrument. I haven't had it apart, but it might be possible to tap into the circuit to transmit the measurement to another instrument.
posted by db at 9:55 AM
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