Issue with top layer looking like extruder has been dragging through it

[Horendus]

Im new to 3D printing and have so far managed to solved my initial issue of a terrible first layer however now im having issues with my top layers looking terrible and ruining my prints.

See the picture bellow
Poor Top Layer.jpg

It seems by the time its doing the top layers the extruder is to low causing it to drag around the top layer messing it up however maybe its just to much filament has been used which really adds up by the time it gets to my top layers

How can I get a normal looking top layer?
Iv tried a range of temps (200c > 225c) and speeds (20 > 100) but I get a constant top layer result.

I have only been printing at .3 res with blue tape and heater bed off.

Im using ReplicatorG with a CTC 3D printer from China.

Iv managed a few nice prints however when there is flat top layers they look like the above.


Any thoughts??

[Davo]

It looks like you are overextruding, so the material is building up into the area the bottom of the nozzle will pass through.

Do you see this on intermediate layers as well? Getting worse and worse, the higher the layer?

[Horendus]

Thanks for the reply!

Yes it does seem to get worse and worse...however its harder to tell on the example print I gave you because the printer head kind of covers the whole thing during the print process.

How do I adjust this or compensate? Im using ReplicatorG.

By the way those parts im trying to print are to add bolstering bearing holders to my back rods as im trying to eliminate this waving effect I get by the 3rd or 4th layer on large flat surfaces (see pic bellow).
Strange thing is on the bellow print example the first few layers look AMAZING, then suddenly those wavy lines start to appearing after a few layers go down....

Thoughts? The bearing holders are from Thingiverse and are from a youtube video.

Waves after 3 or 4 layers.jpg

[LambdaFF]

While I agree with Davo that you seem to be over extruding, and this is the biggest issue, it would also help if you added a slight "up" movement to each travel in your slicer.

[Horendus]

How do you add a slight "up" movement?

Im using ReplicatorG

Here is another example of an in progress print.

Its actually looking great but the head still is making drag marks across layers!
Scraping.jpg

[Davo]

I think you have two problems:

1. Your Z zero position leaves a small gap between the head and bed, and

2. Your head is overextruding.

Why do I believe this?

I believe that on the first few layers, the extra Z distance allows the material to go down without any problem, but as the height increases, the extra flow overcomes that initial extra space and begins to force material up into the path of the print head.

This is why I advise people not to decide if their flow rate is correct until they are at layer eight or ten, so that they know any error in the Z distance (which can mask over- or underflow) has been overcome.



EDIT: I don't know how to make these adjustments on your platform, sorry.

[Horendus]

So I resolved this issue and it was really to do with my desk not being properly braced against the wall. The patterns I was seeing was the desk slightly resonating (wobbling) ! (not really noticeable by the eye but shows up in print patterns espcially in speeds above 40mm/s)

In all my 3D printer research I have never read about how important it is to have a SOLID build platform, eg a braces desk with minimal moment possible!