Unlike 'Neo' you probably can't straighten your Z rods by sheer will. It is however very important to have straight rods. A wobble on your Z axis will cause your walls to be irregular and far from a smooth build. It most likely won't compromise integrity of the object, but it won't be as smooth as it can be.
Straightening the rods is a simple thing. Put the rod without the nuts or bearings on a flat surface - glass makes a good surface - and roll the rod around. You'll immediatly notice if there's a wobble in it. On my rods i found the exact spot of the bend by pushing one side down, and looking for the point on which it tilts. If you know where to bend it, slightly curl the rod - do it with minimal force - and repeat it untill the rod rolls flat. You could also opt to just buy a new rod.
The user 'TwoTimes' on thingiverse came up with a brilliant addon to eliminate any form of wobble (Wobble Arrester). Aside from the bushings i have all the parts prepared to add this to my bot. I'll post pictures and configuration as i go along - check the blog archive for the link.
The stepper motors are strong, so strong in fact they can withstand a massive beating with a hammer! When i built my bot i made a capital mistake, get ready to point and laugh:
"When i put the pulley on the stepper motor that controls the Z stage, i noticed i accidently used the pulley on the X stage, and had threaded the inside by forcing the threaded bolt through it. Because the inside was now threaded, it didn't fit smoothly on the stepper motor anymore (not even with a whole lot of sanding). Since i figured i ruined the pulley i forced it onto the motor with a hammer(whack!). Testing the motor after each bang i grew interested in how much pummeling the motor could actualy take. Rest assure that it can take a beating far greater then your furniture can take. I was amazed at how hard i hit it forcing the pulley in place, and watching the stepper motor still happely spin!! I won't however try it again, nor do i advise anyone to try it out, unless you have a spare stepper motor you're willing to molest."
you can stop laughing now ;)
As for the electronics, i have one capital piece of advice. The cable you use to connect the motherboard with the extruder controller, should be S/STP specified (not S/UTP!). S/STP is short for "Shielded Twisted Pair". The makerbot designers use a xTP cable to keep it cheap, and although the cable suffices in many ways, the wire pairs need to be shielded in order to keep noise polution out of the signals between the boards. Noise can cause interference and disturb the build process in many more ways you can imagine. So keep your wires (Nichrome, Thermistor) away from your filament drive motor - and the communication cable should loop through the front of your case towards to motherboard to keep interference away from the signal. You should be able to buy an STP cable in any computer hardware store. Keep it as short as possible.On a final note about the building of your bot:
Don't assume that when it's built, you're done. Always keep in mind you're going to take it apart again. First two times i was reluctant to dismantle the whole thing because i believed the issues (bent z rod, loose bearing) i had were minor and didn't require dismanteling. Untill i could tweak skeinforge no more and HAD to fix the wobble in the Z-rod by taking the rods out. Always keep in mind that mechanical flaws leave a far greater imprint on your objects then you might imagine when you first start printing. It's homebrew, DIY and requires allot of maintenance. Any slight flaw in both mechanical or electronical parts immediately show in your to build object!
Happy botting,
Kling3r
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