Hello all! Just wanted to throw this out there for those that didn't know about this site. It's called toolwatch and has been very close on testing the accuracy of my mechanical watches. It's not a timegrapher by no means, but it's simple to use and free. It has worked much better than any of the apps I have used on my droid. All it does is give you a good basis on how your watch is running. The key to using it, correctly, is making sure you synchronize your watch with the Naval Observatory Atomic Clock prior to doing any measurements on the site. Providing your watch has a seconds hand and hack capable movement this is easy enough. The site is easy to use and you can add multiple watches, keep logs, etc. The links are below! Give it a try if you haven't already!
The site
https://toolwatch.io/
Synch here
http://www.usno.navy.mil/USNO/time/display-clocks/simpletime
The site
https://toolwatch.io/
Synch here
http://www.usno.navy.mil/USNO/time/display-clocks/simpletime