Shorter knobs for rheobus

[boyRacer]

I just bought aluminum knobs for the rheobus i was building but the knobs were too tall and they're preventing the door on my sx1030 from closing all the way... i grinded them down but of all the places it had to come in contact with it had to be the small part that extends in. anyone know where I could get shorter aluminum knobs... not from caseetc because their knobs are too tall too. thanks.