I sent my R2 back yesterday. Bent rods and other poor quality build issues. I tried everything I could think of and everything Jerry Grauman told me to try. Jerry doesn't feel the rods were causing the effect that I was getting (looked like vertical ringing about every 1mm and had a very tactile feel to it). He felt since 8mm rods equal 25.13mm revolution, it wouldn't cause 1mm spaced artifacts. I feel it did, since all the rods are bent, fighting each other and causing binding. What else could it be? Maybe a bad board? Bad stepper motors? I pulled the top off and disconnected the motors to see if there was binding. There was a pulsating like binding. Jerry said it wasn't the bent rods that were causing the binding. Quote from his email, "The pulleys that are attached to the small vertical belts in each back corner can rub on a bearing that is in the wall of the chassis/body of the printer. Can you please move each one (there are 2) of these pulleys slightly away from the wall and put a dab of lube between the bearing and the pulley? I think you will see really smooth movement after that. " I did what he mentioned, but it wasn't easy because they stripped out so many grub screws in the pulleys. It didn't stop the binding I was feeling. I also asked customer service for replacement grub screws and they said they don't stock them and I should get them from McMaster Carr. LOL, not a big deal but not professional. Another build issue I noticed, When I pulled the stepper motors, they are screwed through a slotted key hole. When they over-tightened them, they buried the head of the screw halfway through the plastic slot. It deformed the plastic and at least one hole had a crack. The plastic was so deformed there was no longer a slot. Now I know they shouldn't have over-tightened them, but maybe they should have used a metal back up plate for that area or even washers for better distribution. Even though my machine had a broken Z limit switch, I don't believe it was from carrier handling. My box had no visual damage and the missing limit switch lever was nowhere to be found. It was not in that machine when packed. I unpacked in a confined area and it should have stayed in the compartment with the electronics. Also, if handling bent those 8mm rods, I think there would have been apparent damage to the box. My suspicion is poor source of parts or during installation. So for replacement, I requested it at least 5 times. July 12, 14, 17, 19, 26th. Those requests went to Customer support, Jerry, Coby and Braydon. Not once did anybody answer my request for replacement until I posted a public review where I knew they would see it. I would say there are more than 35 emails back and forth about this with plenty of pictures to show them. I have plenty of experience with 3D printing. Multiple materials on multiple machines. When I asked for a replacement power supply due to the grumbling fan that sounded like it was ready to die, they said no it'll be fine. Public post to kickstarter and then that was fixed. I asked for replacement rods weeks ago, still nothing. We don't have them in yet. Would be over a month to receive them since first request. Doesn't matter now, machine is finally being replaced. Told to get my own screws, No to power supply replacement, no response for replacement or repair? I had to go public? And at no time was I disrespectful. I still believe in the R2, I still have faith that Robo can make this right. But so far my experience with customer service and the R2 has not been a positive one. Sorry for a long post.