Printrbot buildup off filament question

Hello all!

I just received and assembled my printrbot simple metal and all went great. I have many succesful prints and have already used all of the provided filament.

On a few of my prints, filament will build up at sharp corners. The extruder tip will hit this buildup when it passes over to other parts of the print. I have tried to print an adjustable wrench about five times once with a raft, but the small bits that turn into the worm drive get hit by the head and usually get knocked off of the print.

What parameter do I need to change to fix this problem?

I have already set the adjsted e-steps on my printer. Could it be my Z axis is too low? Temperature not set right?

Thanks

The filament given is PLA. What are all the parameters used ?

Have you done the Z height adjustment with M212/M500 as per brook's video ? A photo of your issue would help.