Are you using a build guide? If so, what does it say?

If not, maybe try Google to find one.

I looked for some info regarding your issue, but cant find anything that specifically talks about it. I'd say drill it out, because if its threaded then it will want to either pull the frame together or push it apart when the motor turns, and you might risk cracking your frame. It's just my opinion though.

You could also contact the supplier you got it from and ask for some clarification