Need help tuning my printer

I am fairly new to 3D printing and this forum, i'm pretty sure this is where I would post this question.

I ordered a prusa i3 printer from ebay about a year ago, and only started trying to dial it in now. At the time I had no idea about all the different parts and things needed to properly dial it in, and the post had no specs for any parts either.

I am currently trying to set the voltage on my stepper drivers because my extruder is only extruding 30mm when told to do 100mm and apparently this is one of the first things I should be doing to fix it. I pulled out my multi meter and measured between 0.315 V and 0.320 V across all four of them.

I am now stuck in that I do not know what they should be set to, from what I can tell this board is a GT2560, but with my untrained eyes that is all I could find out about it.

Could anyone with a bit more experience with these give me a hand?

Before worrying about the stepper current, look at your extruder and see if it is gripping the filament properly. There should be light toothmarks visible on the filament. If there isn't enough tension, the drive gear will slip, under-extrude, and fill up with scrapings.

"my extruder is only extruding 30mm when told to do 100mm"

your extruder may need calibrating but still.... thats very short

Looks like one of those Geeetech printers. I have one too. A true mission to get it to print properly.. After two years, I'm still struggling.

From your post, I can think of two possible things: 1. wrong e-steps (many excellent tutorials out there, for ex. [www.youtube.com]) 2. under extrusion. If you hear clicking coming from your extruder when printing, it means the filament isn't being pushed out properly. It could be a) bed leveling issue, b) low voltage which means no power to push the filament (geeetech recommends between 0.8-1.2 I have mine at 1.0), c) extrusion multiplier is high, or d) clogged hotend.

Let us know how it goes.

The voltage on my stepper drivers are around 0.320v, that sounds awfully low compared to your 0.8-1.2, is it possible we are talking about different things? or are mine just that far off?

There are at least three different versions of the A4988 drivers out there. The difference lies in the current control shunt resistor value.
Before copying other peoples Vref values, look here for detailed explanation.
It also depends on your steppers max. current capabilities.