Welcome! Log In Create A New Profile


Weird Z artefact

Posted by drmaestro 
Weird Z artefact
March 22, 2017 03:31PM

I am trying to discover the reason for the following artifact. I have printed a unicorn as shown below:

The print was oriented horizontally, as seen on the picture.The left side, which you can see on the first picture, is OK, except 2 linear prominent disalignments at the neck of the horse. However, look at the other side:

There is a wobble like artifact, which is very prominent on this side.I assume it isn't Z wobble, as I am using linear rails and steppers with lead-screw shafts. Also it doesn't have a periodicity.

What is it? Why is it asymmetrical? Any ideas how to fix it?

Re: Weird Z artefact
March 23, 2017 06:20PM
Found the solution!

This kind of wobble was a chronic problem of mine and I have posted about it before. It did come and go apparently randomly.

I was using the Prometheus hotend, but had some consistent feeding problems. I couldn't finish many of my prints, as the hotend was jamming at random intervals. While I like Prometheus, as it is very small and can heat up very fast, I gave up and changed it with an original E3D V6. When I did that, I used the same X axis car that I was using for the Prometheus, however the mounting size is slightly different so while E3D fits, there is a very small gap. I use a clamping machanism which presses the hotend to the X car, so it is quite stable. If I tried to move the hotend applying light pressure, it didn't move at all. If I applied more force I could see a very small movement but I was assuming that it was OK, as the hotend wouldn't have to receive this much abuse during normal prints. Well, it seems that I was wrong. The hotend should not move, even the tiniest bit! I thought that was impossible, because even if the hotend didn't move, it would flex the X car, resulting in movement.

I tried to fix this problem by re-designing the X car for a very snug fit for E3D. Also, I used Colorfabb XT instead of PLA or nGen (my previous car is made frpm nGen). The net result is a very very thight fit (seriously, I cannot fit the hotend manually, I have to use something metallic to pull it) and a very rigid X car (it doesn't flex). The net result: Perfect prints.

TLDR: When people tell you your hotend might be wobbling, listen to them and know that even the slightest movement can degrade printing quality considerably.
Sorry, only registered users may post in this forum.

Click here to login