failed prints

[Jon Bondy]

I usually print these beasts one-at-a-time, but to save time (so I could print over night), I decided to try to print two at one time.

The first attempt failed with the print shifting along the X axis at the very beginning of the print.  I wondered if perhaps the parts were too close to one of the edges, so I rotated them 90 degrees in Z and tried again.  This time the parts shifted in the Y plane, and at the END of the print (although there is a little jitter visible about 10 of the way through the prints).   Notice that the shifts are along the same axis of the PART even though the parts were re-oriented. Pictures here:

http://www.jonbondy.com/20170318_090152a.jpg

http://www.jonbondy.com/20170317_221908a.jpg

I have printed these parts before without a problem, and the printer has been a workhorse for years.  I'm not sure where the problem is or what to try to diagnose it.  I will try printing them one-at-a-time, but I'm just flailing here.

Anyone seen something like this before?

Later...

I have had problems with the X axis "sticking" when moving around at high speed in manual mode (but never before during a print).  On a whim, I put some oil on a cotton swab and oiled/cleaned the two guide rods for the X axis.  Loads of black crud.  I had to do this perhaps 8 times before the swabs were clean.  I'm not sure whether this was behind the failed prints.

What do the rest of you do in terms of ongoing maintenance for the X axis?   Note that I have never had a similar problem with the Y axis (but I rarely move the Y axis manually).

Thanks!

Jon

[John D]

Hey Jon - long time, nice to see you a1 is still printing.  I've had the same sort of thing happen, but it's been a long while and I'm pretty sure it was before I moved to smoothie.

In my case Slic3r was inserting an insane travel move going from part to part, but only at a couple of spots in the model. Those would cause a skip on the travel and then the expected offset layer.  At the time Chris and I were going back and forth about it, and I think we basically came to the conclusion that 1] slic3r was doing something odd, 2] Marlin was allowing a move that was too fast and 2] the A1 has a low tolerance for "too fast" without dropping a step.

W/regard to maintenance - I've actually taken my simo's apart and cleaned and re-lubed them a couple of times.  There were some really good instructions on how to do that floating around, but I've not seen (or looked!) for them for a while.  I generally clean the simo screw with a super-lubed rag one or twice a year, usually when I'm fixing something else. 

[Jon Bondy]

John:

Great to hear from you!  And what you write completely conforms to what I observed.  I am using Repetier Host and Slic3r, and the problems only occur when I try to put "too many" parts on the build plate (triggering the "insane travel").  So I feel relieved in that the printer probably is no worse than a year ago, but frustrated that I cannot print multiple parts without these issues.  Is there some way to tell Slic3r that I do not want to move faster than a specified speed?  Could this resolve the issue (albeit with slower prints)?

I would love to find the maintenance instructions for the SIMOs, if someone has them at hand.

Jon

[Frank]

I've found that my SIMO's "chatter" when they need maintenance. Particularly the X axis.
 You can actually hear the noise level during a print increase.
while I've had my SIMO's apart
see http://www.r2-3d.media-conversions.net/printer/A1.rebuild.2.html
at least far enough to remove the carriage.
My current "preventative maintenance" consists of wiping the rails with some teflon dry lubricant
that's been sprayed onto a paper towel and then running the carriage back and forth to distribute
the lubricant on the rails. Wipe off any excess lubricant that accumulates at the end of travel.
[don't spray directly from the can, goes all over!]
and yes, I get black 'crud' on the towel when I wipe too.

Frank Pirz
Media Conversions LLC

[Jon Bondy]

I recall hearing that I should lubricate the rails but never the lead screw (to prevent the screw from attracting dirt), but John lubricates the screw.  Any thoughts about that?

[Frank]

Jon
That's why I'm using the teflon 'dry' spray. it comes out as a liquid, not supposed to leave a sticky residue.
it doesn't leave a residue, but spraying directly will wind up with spatter all over the place, including the bed
where you want things to stick.

I've wiped the lead screw from time to time, but imho that's not where the chatter comes from - the carriage isn't tight on the slide.