Start making rear part

I got all of tube and plate.

I started making rear part of python.

First cut seat stay.

But the seat stay's measurement is too big to rear axle screw. The outer diameter is about 16 mm and inner one is about 13mm. The rear axle screw's diameter is 9.4.
So I tried making tube to fit to the screw with Metal Lathe.

Then I cutted rectangler tube of rear parts and drilled 16 mm holes one both side of it.

Then, I check the horizontality,,,,,

OMG ! Next time I will need adjusting it with file. Metal work is very hard for me.