Me and my friend recently decided to make a 3D printer for next years local Mini Maker Faire, and I had an idea about using servos for x and y axis of my printer, because of the position feedback. It will be a pretty small printer (like 12cm by 12cm build plate) so 9G cheap ebay servos will do. For the z axis Im planning to stick to stepper motors, as well as for extruder. My question is does there exist any 3d printer firmware that supports servo motors for axis or can something like GRBL be adapted to give stepper degrees instead of motor steps.
Any help is appreciated

 

I doubt you will get the resolution or the power using little RC servos. To do it properly with servo motors, you do not use RC "Servos" but motors with encoders and you count the pulses.
If you want to make it on the cheap, have a look at using steppers from old DVD drives or similar. There are quite a few sites that have done that.
for example...
http://www.instructables.com/id/eWaste-60-3DPrinter/
To run real servos on a 3D printer would be a great way to go but it is definitely not a trivial exercise to get the software going.

 

https://hackaday.io/project/11224-mechaduino

There are videos of it being used for 3d printing and being able to push the print head out of the way and it self correct and continue printing in the correct spot..
From what I've seen this is your best bet so far based on whats out there..
I've always wanted a "low cost/diy" servo cnc solution plug and play solution.. Thats the closest I've found so far..

 

That video shows "real" servo motors, not the little 9G servos.

These 3 wire type servos will not work.
But the bigger servo motors with encoders and controllers would be great. Very good way to go .

Have fun doing the software
If you get it going well you will be onto a good thing.