Tricolour Mendel - Top three tweaks,mods to enhance printing?

So my printer is built, albeit as a mono unit at this stage and I'm trying to fine tune the results before moving on to the colour side of things. Could you suggest 3 things that improved your printing? Mine are:

1) Take your time dialing in the chassis build and then go around again from the start. Fortunatly all the motor cals were already completed before shipment.
2) Next is to use PVA on the glass to get the prints to stick reliably. Not sure I have found the best mix for this yet. I'm using 1:4 PVA to Meths but elsewhere people mention using water. So need to try that.
3) So far the biggest single change to print quality was is to print with a 120mm 3 speed Antec PC fan in front of the bed connected to the fan output on the controller board. As can be seen in the attached picture. Or should I be able to get the print on the right without using a fan?

1. I have recently added some extra frame alignment instructions, which can be checked at any time during the build: [reprappro.com]
2. Kapton tape (supplied with the kit) applied to the glass works fine with PLA, and lasts for months. Clean it with Acetone or Isopropyl Alcohol, not oil-based cleaners (leaves an oily residue) or Winolene/Windex - this usually has an antistick component, which is the last thing you want!
3. When printing small components, or layers that print quickly so the previous layer doesn't have time to cool, or bridging, a fan is pretty much necessary. I'm just getting around to updating the currently blank 'Improvements' page; I'll add an x-carriage fan mount, picures and instructions soon.

RepRapPro tech support

@droftarts

Hi,

- Do you think is possible to print PLA with Glass+kapton without activating the hot bed ?

It is long time I use the kapton on the glass on my RepRapPro with good results BUT I always activated the hot-bed at 55C
I tried a couple of time without the hot, and the PLA did not attach well (detached during print) and sometime it bended (not as much ABS but it bended !!)

- Should I try again with more "cold" experiments ?

Regards