Pulled some wort to measure the gravity by hydrometer.
The reading is exact what iSpindel reports. After applying temperature calibration, it is 1 point off.
It's not perfect but good enough for me. I would like to share some tips of calibration:
1.The nature of accelerometer is noisy. The reading won't be steady, even if you fixed it on solid ground. However, unlike gyro, the reading won't drift too far. Therefore, be patient. Take some readings, say 10, and use the median value.
2. Make sure the iSpindel floats freely without touching anything.
3. [Edited] Try to run the calibration at the same temperature, say 68F/20C. I think temperature correction to hydrometer is not necessary. The working principle of iSpindel is the same as hydrometer. The higher gravity, the more they float. When the temperature drops, the "gravity" rises. The real gravity rises because the volume of water shrinks.
When we brewers talk about "gravity", we usually means the gravity calibration at 68F or 59F, because the amount of sugar is what we want to specify. Don't mess up them.
If your are using refractometer, make sure you use correct correction factor. I think you don't need to apply the correction if you are using sugar dilution method.
4. Make sure the sled or anything doesn't move after calibration.
The reading is exact what iSpindel reports. After applying temperature calibration, it is 1 point off.
It's not perfect but good enough for me. I would like to share some tips of calibration:
1.The nature of accelerometer is noisy. The reading won't be steady, even if you fixed it on solid ground. However, unlike gyro, the reading won't drift too far. Therefore, be patient. Take some readings, say 10, and use the median value.
2. Make sure the iSpindel floats freely without touching anything.
3. [Edited] Try to run the calibration at the same temperature, say 68F/20C. I think temperature correction to hydrometer is not necessary. The working principle of iSpindel is the same as hydrometer. The higher gravity, the more they float. When the temperature drops, the "gravity" rises. The real gravity rises because the volume of water shrinks.
When we brewers talk about "gravity", we usually means the gravity calibration at 68F or 59F, because the amount of sugar is what we want to specify. Don't mess up them.
If your are using refractometer, make sure you use correct correction factor. I think you don't need to apply the correction if you are using sugar dilution method.
4. Make sure the sled or anything doesn't move after calibration.
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