Eufymake E1 Cartridge Mod Center Hole

Here is the jig I used to center my hole for the threaded inserts I installed into my EufyMake E1 cartridges so that they can accept aftermarket/ third party ink. These are meant for the M8 threaded inserts I used in my video. Do not drill the top of the cartridge! Be sure to use a soldering iron or similar to remove the material. 

Video of modification here.