The dreaded "Y" Skip (Page 1 of 2)

Since your RAMPS install have you adjusted the VREF of the steppers?

I have a similar issue, which i thought was over heating in my SD3. In the end I realised was the set screw holding the pully to the shaft that is slipping. You can try taking the set screw out and screwing it back in again

The other one which bit me was the actual filament tension.  Occasionally it would bind on the spool when the head was travelling forward, causing the "Y" skip exactly as you are seeing there.  The filament would then "shock" loose, so you couldn't tell the problem unless you caught it in the act.

Well, in my case it turned out to be a bad stepper.  Once I replaced it with a spare, the skip went away.

This community is so amazing!  Almost every time I have come here with a problem with my machine, someone else has posted the same problem and everyone has pitched in to figure out what is wrong.  I have had this exact problem with the last 2 big prints I have done.  I have just switched to a newer computer for my printing machine, one that I felt had a better processor and memory, only to find out that the on-board video sucks so bad that the drawing of the project has to be turned off during the process.  Now this stepping thing has hit me and I was looking at the computer as being the culprit.  I will try lubing the Y axis rods and see if that helps.  Any other suggestions would be deeply appreciated!

Which board do you have (Sanguinololu, Printrboard, RAMPS, etc)

If you got your printer about the time you registered than it is most likely the Printerboard REV E.  Should be printed on the lower right of the board as viewed from the back of the machine.  Have you adjusted the VREF for that motor?

No, I have never checked the vref, for the Y axis correct?  Is there a link to a "How To" video or instructions?  Will I need an Fluke meter or will a Harbor Freight cheepy be good enough?

I was reading on another thread and they mentioned the motor being a little week for the job.  Is that something I should look into replacing? 

The printer is being used in my Jr. High Computer class and repairs and replacements will probably have to come out of my pocket.  It is too hard getting the school district to do anything.

The "original" board that came with the SD3 was the Sanguinololu.  Sometime mid last year they switched to the Printrboard.  Take a look at your board in the back.  Which one does it look like?

Here is a Sanguinololu

Here is a Printrboard

Notice that the Printrboard doesn't have plug-in type steppers like the Sanguino.  On both boards you can adjust the voltage (vRef) using the little trimpot.  Adrian has posted a tutorial on ho how to adjust the vRef and the values you should adjust to.  Do a search for vRef adjustment or tuning.

Even without that reference.  Try adjusting the "Y" trimpot clockwise just a little, 1/8th of a turn, and see if it helps.

fingers crossed?

Well it didn't do it as badly but still isn't good.

I have previously loosened the stop nuts and adjusted them to make circles more round but I will give it a try again and check the VREF also.