Offset Layers

Mark have you tried tightening the pulley on the x axis? The set screw might not be tight enough, causing slipping on the motor shaft

 

Something I just noticed. I am printing another test to prove it.
When I print something long (tall) and narrow, NO X slippage seems to occur.
None. Nada. It was only when we switched to printing the model that was wide (i.e. had a lot of X travel) that it started showing up.

With that in mind I tried re-tensioning the belt. Seemed tight, but WTH. So now it is about as tight as you could want it I imagine--I can't see how to get it tighter. It seems a little tighter than it was before.

I am trying another tall, skinny model that will be about 6-8 inches in the Z axis (1/4 x 1/2 in the X/Y). If it does no X axis slippage then I will try another copy of a wider, shorter model to see.

 

No, but let me give that a shot as well. I couldn't manually turn or move it by hand.

 

My bad I thought it was the y axis that was off and it is definietly the X disregard my earlier post about the bed stuff that was Y related switching thinking caps


QUESTION Have you tried printing a smaller solid object like a 1 inch cube or something to see if translates across solid fill

 

try printing a low flat wide solid object trying to get the long axis of the print on x but make it solid

 

OK, great idea.

I am printing the skinny (very little x/y, but a lot of Z) model.
Assuming that, again, prints with no X/Y errors I will go for a short stubby (lot of X, very little Z) and see what we get.

 

OK, last nights results are strange. I am attaching the photos (little blurry--sorry it was late).
The tall skinny pair of objects printed with some spiderwebbing, but no X axis malfunctions. I then printed the long-wide model which was a LOT of X axis movement, but it also printed without any issues.

I am going to try the original model that had the problems again, all I can think is that maybe the belt was a bit loose and tightening it helped (but, IMHO, if that is true then it is *very* sensitive to the tightness of this belt).

Lesson well learned if that is all it is

 

I am also going to pop the case off and check the pulley as was suggested. But I am less suspicious of that after the good prints.

 

tbh I think the issues is the ringing effect I talked about, I think though, in another thread. Your original print had the large opening in the center and all of the other prints were solid and even in the tall skinny where you would have exptected teh same shifts to occurs they did not because they were solid. If you were goin g to try again I would seriously consider altering some of the speed settings. it does not sound like it will work but I had the same thing sort of happen on a small hole
not seen in this pic is that the outside edge on this face of the print which ran parallel to x had the same slight shift outward though with it being this small it ended up being just rougher but again it was only in this small vertical spacing.

 

It is currently reprinting the original model and about 1/4 of the way done. It is at or past the spot where it would fail previously and -- it is flawless so far.

I will update this when it finishes to let you know, but I am thinking at this point that the belt tightening did the trick -- or magic

It just did not seem loose, but clearly that has affected it in a positive way. Assuming it does finish as well as it has started it bears beating the drum that the belt needs to be tightened...and it is (or was for me) tough to see that it needed this.

 

It worked, flawlessly. Clearly the belt tensioning did the trick. It did not seem loose, but clearly it was loose 'enough'. In fact I would venture that--at most--we tightened it ONE more tooth of the belt. That is it. (photo attached just for completeness to show the completed print so you can see the difference. The photo is after post-processing which helps explain the shine).

Before, even with small models, sometimes the first couple of layers would have a bit of offset that would then self-adjust. Now, that is also gone. It prints exactly as I would expect it to.

So people--tension your belt

and thanks to all of the suggestions and ideas, we now know what to look at when these glitches start to happen.
Printing now looks GREAT!

 

One last comment. Today I noticed the X axis 'drifting' a bit. Each successive layer slightly off.
This absolutely was the Allen screw in the pulley loose.

BTW: it looks like there should be two of those in there, but I only have one. Is there supposed to be two?

I am putting some locktite (tm) on that bad boy

 

that one is ok to loctite I do not know if there are two as I am in the middle of a print and can't check

 

true, and the Y axis ended up needing the same treatment.
Robo3d support seconded the notion of the pulley.

In my own defense let me say that it was not obvious it was loose until you either tried to tighten it with a wrench or take the belt completely off.

 

Hi Mark,

I did not get a chance to see the entire thread but it looks like that slipping is on the X axis, did you check to make sure the belt is tight? Let me know. Thank you

 

That problem was resolved by tightening all of the belt drive pulleys to the shafts (they were loose) and applying Loctite.

 

X axis, cut the zip ties that hold the belt by the motor (on one side). Tighten the belt as many notches as you need and reapply zip ties.

Y axis, remove bed. No zip ties hold this -- it is looped through a clamp/connector at both ends. Remove it from one end, adjust it to take up a notch or two and re-install the bed with the belt in-place (it runs between two pulleys and drive gear under the board). It was easier for me to run the belt through the gear and pulleys with one side attached and then attach the other end to the clamp/connector as tight as I could.