Disc Grinder Restoration and Conversion - 110V to 20V by Rewinding

Disc Grinder MG-125J
AC 100V 50/60Hz 8A
125 mm x 16 mm x 22 mm. 4300 m/min.
Power in 780W
Power out 480W
MITACHI
Tokyo Japan

I bought this tool from Japan recycle store without testing. When I use it, it does not seem to work well, because some bearings are broken. By replacing those broken bearing, this tool will work normal. But I want it runs with battery instead. As a result, I can do it.

Video sections
00:33 before restore testing
00:59 disc grinder blade removal
01:18 disc grinder disassembly
03:28 broken bolt removal
07:48 armature disassembly
10:04 commutator bar install
10:25 DC rewinding diagram 18V
10:29 DC armature rewinding
16:40 permanent magnet install
16:56 motor testing
17:26 carbon replacing
20:14 battery adapter mount
22:54 painting
24:48 battery disc grinder assembly
31:15 battery disc grinder grinding test

I hope you find this video useful and enjoy it!
Furthermore, I am happy to receive feedback, suggestions to improve myself.
!!! I'm sorry for the mistake if I did in this video !!!
Thank you very much for choosing to watch my video!
Have a nice day
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