Welcome 
…
…please spend a little more time in the forum (or even complete the discobot 
tutorial… see your DM or the FAQ to be able to… 
( of course you could also use an external link… but if it disappears no other could learn from this…)
This said…:
So you “original” blend does not have this difficulties ?? Then maybe you have to scale it up ( or down ) because this may be precession problems ??
For example: you applied scale ( Ctr-a → Scale) …so it has a scale of 1.0 for x,y, z ??
( Also you may have some trouble with 3D-printing later because STL has no real “dimension”… there where some posts about this… you may try the search feature 
top right… or ask some more about your specific problems here… )
And… ( as you can see while i was away from keyboard after starting this reply… )… there are other who much more about 3D printing… ( for example the mentioned 3D printing software… )