First Build, some doubt (Prusa i3)

Hey, i'm almost done with the list of components for my first RepRap but i've some doubt, mainly with the extruder and his support.

I'm thinking of builing a Prusa i3 Boxed using this printed parts ([reprap.org]), but i was thinking of using this ([www.thingiverse.com]) x-axis carriage insted of the standard/old one (the one that can be found on the page with all the other printed parts).
For the extruder i was thinking of this one ([www.thingiverse.com]) with a j Head MKV.
In addition i'll probably add this ([www.thingiverse.com]) fan support for cooling the barrel,

Now here comes some doubt =)

1-It's my configuration correct? I've researched it and it seems fine to me, i presume that i can exchance the x-axis carriage without problems or am i wrong? For my understanding the original versione is the one for the Boxed and the one i would use is the one for the single plate design.
2-There is a better carriage/extruder configuration that comes to mind?
3-Last thing, the fan/fans, it's not all perfectly clear to me, i've read that there are 2 parts that benefit from dissipation, first the barrel, for preventing the heat to rise on the extruder printed parts and melt it, and second the print, for various reason, am i right?
Any suggestion on how i should configure the fan?

Thanks for your time, hope you guys can help a newly discovered Reprap enthusiast!

Edited 1 time(s). Last edit at 08/13/2013 11:15AM by Nova.

If this is your first printer, then I'm going to give you the same advise I was given. Stick with the stock parts so more people are likely to have the same setup as you, therefor increasing the number of people who can help you.

Fans, you need one blowing on the top of your extruder when printing PLA. All kinds of stuff goes wrong when you don't have this. For ABS you don't need it. Fans for cooling PLA parts and their placement is less standard. Again no used with ABS. I have seen all kinds of configurations. Some don't even use them when printing large PLA parts where the head isn't going to be going over a tiny area over and over again real quick or even when printing a whole plate of small parts. When the head is in any one area for too long things get mushy. I have used a six inch desk fan on low from about two feet away for some prints, a 50mm fan strapped to one of my i2 uprights for others, and there has been times when I have wished i had a 30mm fan mounted on my carriage blowing right where the head is. This would be fore printing really find parts by their selves.

Thanks for the advice, i would use the original parts but i dont like that in that piece the extruder is holded by a bottom plate, however, I will consider your advice =)

Regarding the fans, i have seen all king of setup and im still a bit puzzled, in an average situation printing PLA i'll need a fan pointed on the upper part of the extruder (the red part) right? just to help cool it down, and in some other situation (that i'll explore later probably) i might need another one pointed to the head (the blue part), or even somewhere else?

Sry if im so thorough but i like to be informed before doing something ^^

Edited 1 time(s). Last edit at 08/13/2013 05:37PM by Nova.

Yes, you always need one on the red part for pla. You will turn it off for abs. Then a second one depending on what your printing. It will be aimed at the part and in some situations would be attached to the x carriage so its blowing where ever the head is currently printing.

im not having fan for pla(actually i have, but im to lazy to mount them ), just filling the plate with more parts...

That's what I meant about not needing the pla fan all the time. More parts means each area gets more time to cool before the head gets back to it, so you may not need a fan.

Half of learning how to print is learning and tuning you printer. The other half is learning how the plastics behave.

I built my first i3 recently with that extruder and was very easy to get help. Would definitely recommend it. Not sure about the x carriage though

tomas02 Wrote:
-------------------------------------------------------
> I built my first i3 recently with that extruder
> and was very easy to get help. Would definitely
> recommend it. Not sure about the x carriage though


Thanks all for your help!

Actually i've studied the original .scad from Prusa and the code for the original extruder can be easily modified for a j head, is an option provided in the code.
So i'll probably use that extruder and all the original parts for the initial build, maybe after i'll try some different extruder, once i can print them myself!