I have been a cupcake owner for over a year now and despite endless mechanical and software tuning and maintenance, I cannot eliminate these skips, particularly in the X axis on longer builds. I am stumped and don't know what to do next.

Hi!  

I have a TOM, not a cupcake, but I had problems like yours on one of my CNC machines.    If you're getting drift in an axis, it means the motor is losing steps.   There are two ways to troubleshoot this:  optimize the movement of the axis (tune and lubricate, make sure belts are proper tension) and the other is to boost the power the steppers and/or SLOW THEM DOWN.    Stepper motors lose torque as speed increases, so if you slow your machine down a bit it might fix it.   

Be very subtle while adjusting your stepper controllers: a little adjustment makes a big difference, and overpowered steppers will make them HOT- which could reduce their life span.

Cheers, Jim

I have the same issues on my TOM. I have torn it down, made changes and rebuilt it four times trying to fix it. I'm getting tired of the problems and the forums are not helpful as one thread will tell you to fix it by doing the opposite from what another thread instructs. I've had my machine for a few months now and have only been able to get three low-quality prints out of it. They are bad enough that I'm not sure they will work once I manage to get the rest of the parts printed...Any help would be greatly appreciated. If anyone from MakerBot is in the Northwest Arkansas area, I'll provide a home-cooked dinner with my family for help getting it going. :)

My x axis was slipping out of the box. I turned the pot on the x axis driver board 15 degrees clockwise and I haven't had an issue since. On the contrary, I think that your aggressive belt tightening may be making it harder for the motors to reliably turn. I tightened up my x belt this morning and it only got louder, not better!

Lube is next on my list. Anyone got any good recommendations?

I believe your problem has to to with the bearings seixing up for an instant throwing it off from where it thinks it is. I had the same problem. My first prints were awesome, although they were short and really didn't get the magig height that started screwing stuff up. I tried messing with the settings in skeinforge but made everything worse. Anyways, the thing that helped the most was rocking the frame a little bit while the y axis was moving (I think it moved the Y-rods and helped the bearings align). The x axis problem I fixed by just playing with the x beltjust pulled it back and forth to make sure the teeth were cathcing and that there was even tension on both sides.

This happens to me, but usually the cause is the extruder getting caught on a blob somewhere and stalling the motor a few steps. I think the culprit can be warping prints, or too high of an extrusion speed. Last time it happened (20 minutes ago) I found one corner of my bed to be slightly low, so I raised it and am printing again.

I'm also not sure if I'm the ross who answered two posts above. Just in case: I agree with that guy!