Precise angle measurment sensor

I am looking for a relatively accurate and repeatable sensor to measure a static angle. Like a Wixey or similar digital angle finder. This is for a project where a Wixey would not work nor would a rotary encoder. I would like to be at least 0.05 deg or better in accuracy and repeatability. 0.01 deg would be ideal. I am looking at board sensors like the MPU9250 and MPU6050 but they do not appear to have the accuracy I am looking for. I need at least 2 axis of angle measurement, X-Y. Worst case I could use 2 sensors, 1 for each direction.
Does anyone know of a relatively low-cost, Arduino compatible, type sensor like this? I would like it to be around $1-15 but up to $40 if it is of very high quality and accuracy.
Thanks for any help or direction you can give me.

To be repeatable, you need a FIXED base line. What are you trying to do?


God only knows what you really need, or why, but I would have thought a rotary encoder is the most obvious way to get the maximum accuracy - and repeatability.
Google "how to use a sextant"

A vernier protractor can do this:

The digital equivalent would use a high precision rotary encoder (they are available upto millions of counts per revolution!).

MEMS accelerometers are not accurate enough for what you want.

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I came across the SCA3300 [HWT31 Low-Noise Accelerometer Module】3-Axis Acceleration+Gyroscope+Dual-Axis Tilt Angle Sensor with [ High-Revolution SCA3300 Temp-Compensation Chip], It says it is accurate to 0.0035° but I am not sure that is the accuracy of what I am thinking. These multifunction chips talk in g's and with a equation get back to a angle. Cost is $63 on Amazon.
Here is another one: MPU9250
[Bluetooth 5.0 Accelerometer+Inclinometer] WT901BLECL MPU9250 High-Precision 9-axis Gyroscope+Angle(XY 0.05° Accuracy)+Magnetometer with Kalman Filter, Low-Power 3-axis AHRS IMU Sensor for Arduino. It is only $48 on Amazon. If what it says, 0.05° accuracy, is correct, then that one would work also.
What I am looking to do is put this on a table saw to measure the tilt of the blade and the height of the blade. I would mount the dual axis sensor on the arm that moves and can capture both angular movements. I would need to do a little math to compensate slightly for the geometry error on the height but it is minor, around .005" at most. The sensors would need to be calibrated to establish 90° vertical (perpendicular to table top) and 0.000" blade height but that is easy to do. My thought was that this sensor could just simply be epoxied in place. There is no place to easily mount a mechanical encoder setup. i know that would give the best accuracy of all but the effort is not worth it, if even possible physically.
I am curious on what everyone thinks on the 2 sensors I mentioned above.

Too much work. Please make them clickable links.

Here are the 2 sensor links:

Hi, this is planet Earth you have landed on.
We have websites that sell cheap things, such as: Amazon / Ebay / AliExpress.
They sell cheap things that can have counterfeit components, low quality, not certified things, stupidly exaggerated accuracy numbers, and so on. Sometimes a factory rejects a batch, and those might show up on those websites.
Some sellers tell anything to sell something.

There are companies that started cheap but aim for better quality, such as Elecrow. Those products cost more.
There are also good companies that give good information and won't let you down, such as: Adafruit, Sparkfun, Pololu.

Manufacturer's page of the muRata SCA3300 :
Manufacturer's page of the TDK / Invensens MPU-9250 :

They are in the range of 3% or 1 degree accuracy. That is the range for MEMS sensors.

When they are calibrated and a processor is added, then it can be better. If a well known brand that you trust gives certain numbers, than you can trust it. However, everyone can made ridiculous claims on those websites.

If you look at the SCA3300 datasheet you'll see its nothing like that accurate.
Its not clear what the repeatable precision is though, but that's not really relevant to measuring static angles unless you want to go through a complicated calibration sequence, and repeat this regularly - the 0.7% sensitivity error includes drift over lifetime for instance.

For the MPU9250 you may be confusing the dynamic accuracy (gyroscope) with static angle accuracy (accelerometer). The only mention of 0.05 I can find in the datasheet is the pin-spacing in inches.

There may be some confusion about accuracy and precision going on - if you make a measurement, accuracy is your primary concern. Precision without accuracy will help with repeatability, but you will be repeatable wrong... Calibration of a device can greatly increase accuracy, but temperature dependence will probably need to be characterized in the calibration for these devices, and long-term drift may invalidate the calibration regularly too.

Thanks for all the great replies. That was what I was looking for. I know you get what you pay for and the Ebay, Amazon's and other websites can say whatever, right or wrong. That was why I was looking for some of your great feedback. I looked at the mfg's websites initially and wasn't able to make heads or tails out of them. Not like a encoder spec is defined at least, that I can understand.
I have some other ideas on how to accomplish what I am looking to do, a bit more on the mechanical side with a encoder, but hopefully still simple to attach. Some simple string-pot type encoders.

Thanks again.

As a followup to this post on what I am going to use for my angle sensor here is what I found. I am going to get a AS5048 magnetic rotary encoder and make a string pot. I will wrap the string around one of the big shafts on my table saw and as the shaft rotates it will pull the string and rotate the encoder. The encoder is 14 bit and will give 0.05 deg resolution. I will have to do a little math in the controller to convert to the correct blade height and blade angles. This will be a cheap solution with High accuracy. If the shaft I wrap around is larger than my string pot shaft I will also have added mechanical advantage and increase the encoder revs per 1 saw rev giving better resolution yet. The sensors are $12 - 20 depending where you get them. Aliexpress has them and Ebay. LINK
I am going to couple the 2 encoders to a arduino and a OLED display to show the angle and blade height. Probably wont get to it all until I have time this winter but I think I can have all the components and code ready to start with.

Sounds reasonable, although complicated. How would you compensate for slack and stretching in the string? String fabric is strong, but quite flexible, and likely changes dimensions with age, temperature and humidity.

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