gt2 belt center distance & tension

Hi all.

I'm a beginner working on my first project and I have a somewhat basic question.

I have two gt2 pulleys:
Pulley 1: 36 teeth
Pulley 2: 60 teeth
Center distance: 51.5mm
Belt: Closed 200mm (100 teeth), 6mm width

If I drill the holes so that the distance between the pulley centers is the calculated 51.5mm, will there be sufficient tension on the belt?
Or should I drill slits instead of holes to allow for tensioning? If so, how long should I make the slits? Is 2-3mm long enough?

The frame material I'm using is 6mm aluminum 6061 and the stepper is a geared NEMA 17 with 6mm shaft (hence the weird ratio, I only found 6mm bore pulleys with either 20 or 36 teeth)
The second pulley shaft is 8mm.

Thanks for your help.

Edited 1 time(s). Last edit at 10/24/2015 02:59PM by ythonell.

Usually you have to make either the motor or pulley (or the other pulley) mount so it fits into slotted holes so you can adjust belt tension. If there's no way to do that because the mounts have to be fixed, you need to add a belt tensioner in the form of a bearing/wheel mounted on a slot that lets it push against the belt.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

thanks for your input, I'll make a slotted design to allow for tensioning.
It has the added benefit that it will allow to use either standard or geared motors, different size pulleys, etc.