Several questions before getting started

Hello everyone. I am looking to get into 3d printing for the purpose of generating some rough prototypes for some product ideas I'm rolling around.

1) Is there any reason why I should not buy a Folger Tech Prusa i3? http://www.ebay.com/itm/Folger-Tech-...-/231301357105
I'm aware of the drawbacks of the acrylic frame, poor instructions, and I hear the motors are lower end. What else should I know? I'm attracted because its cheap and the consensus seems to be that its a good value.

2) Is there anything that I should buy up front in terms of upgrades. IE, anything to incorporate from square one? LCD? Auto-leveling bed? Specificity is appreciated.

3) I saw a Youtube that suggested users of the Arduino Mega 2560 and RAMPS combo be prepared to reprogram the 2560 in order to get things working well. Just how standardized is the firmware for these boards, and just what parameters are users tweaking in the firmware? How is the an Mega 2560 reprogrammed? Would I need an ICSP similar to using a PicKit on Microchip's products? I have some intermediate embedded programming experience, but I don't want to get wrapped up in a new IDE/new language/new whatever just to get my printer working acceptably. How plug and play is this board?

4) I've never actually seen a 3d printed item in person. How does the smoothness and finish of a well done 3D print compare to an injection molded piece, especially when dealing with curved surfaces?

5) Maybe (Probably) I'm underestimating all of this, but is there any reason why I could not take the exact concept of an i3, buy the boards, extrusions, and make a huge (like 500x500x500mm print area) printer from scratch? From the little I've read about slic3r, you specify your print area, so what is it that's limiting the size of most of these commercial printers? What is limiting the size of 3d printers? Is it an issue of stability?

Thanks for your time.

Sounds like you might want to build your own monster printer. I'll bet you can find some answers to your questions on openbuilds.com. These guys build some seriously LARGE printers.

Have fun...

3)You don't need have an ICSP, open source circuit board include directly a USB port and the atmel chips on the. The only thing you will need is the USB driver so your computer could detect them.

There's really no firmware standard, I already have 2 in my head right now using the same Mega2560 based chip.

4) That's the catch and typical BS advertising. They did post treatment to get nice surface. Object right from the printer is rugous.
Again, your question can be explain in a wall of text, the best way to understand it, is to print over time.

5)Shipping reason, takes too much space, labour effort,etc. Not much consumer would ever buy gigantic printer. The big printer is for the big boys for the industrial world, about 30k to 500k US$. Have a look at 3DS or stratasys system, they are as big as hell.

Size limitations are there for a lot of reasons. Richard mentioned one regarding shipping. That's a big one for sure. These machines can get big and heavy in a hurry and when you're already talking 1000 or more for a printer, hundreds of dollars extra to ship it is going to turn away a lot of customers.

More than that though, as you scale up you start to run into problems with print quality unless the design is put together to handle the size of the printer. The average linear rods and bearings that most consumer cartesian printers use are not up to the task of very long runs, they will sag under the weight of the print carriage. The belts used by most printers are flexible and as such will stretch and contract under load. Longer belts increases the amount of movement within the belt which will hurt accuracy and precision. Components get more expensive because they are being scaled up. As things get bigger they get heavier so more power is needed to move them... and then stop them which could mean stronger steppers. The greater inertia adds to the belt issue mentioned before. Overall size of the machine becomes very large which eats up a lot of desk or floor space. Then on top of all of that, larger prints tend to warp far more than smaller ones do so as the machine gets bigger the need for heated build plates and heated enclosure to mitigate warping.

So at a basic level, yes, one could take any existing design and simply scale up to increase the build volume. Adjustments would need to be made to the firmware running the printer and in your slicer software settings but that's not difficult to do. The bigger concern is taking into account all the things that change as everything grows.

Thank you all for the replies. I looked at some videos on tweaking the firmware and it looks pretty straightforward. Tweaks seem to involve just changing some parameters. I was worried about having to re-write entire blocks of code.

Thanks for the tip on open builds. I would probably hate myself if I did, but I'm tempted to try one of those.

Soofle: Nice clarification on why bigger is harder.

Soofle, what would be the biggest DIY home printer build size that's still reasonably priced and won't encounter many issue's?

No idea at all Bassna.