Unwanted seam appearing in prints on FFCP

[Horia 0]

Hello, I encountered a problem in my prints. We use FlashForge Creator Pro

Here are some photos:

I am using Simplify3D as a slicer.

I printed the handle for nylon bags a few times and every time the seam was there. I changed the orientation and the seam didn’t disappear.

Here is the Z seam for the bag handle:

After that I printed 2 coat hangers and again the seam was there. The model has 3 perimeters. The infill touches the inner perimeter at another spot above the unwanted seam. The Z seam is at random points.

For comparison:

Infill picture:

Seam picture:

The Z seam is in another spot and has nothing to do with the continuous seam seen in the pictures.

Is this from the slicer or the printer?

Edited March 14, 2016 by Guest

[gr5 2,271]

The Z seam is usually where the printer pauses briefly and the Z axis moves. Because of this pause you get extra PLA leaking out. You can reduce until the seam is almost invisible through a few techniques (speed/temp). The best thing to do is lower the speed drastically. Try to get your print volume under 2mm^3/sec if you want higher quality. Whatever your speed was for this print, cut it in half. Each time you cut speed in half the seem will get fainter.

In fact I recommend you play with this in the TUNE menu, try 10 different speeds and mark the part with a permanent marker each time you change speeds and keep notes. By the time you finish 30 minutes of printing you will be an expert on Z seams. Also consider lowering the temperature. This will help the z seam also but only if you also slow it down.

[Horia 0]

I feel that all the odd things in 3d printing are happening to me... :(

I'll reformulate:

This is the Z seam that I wanted to appear in the same place:

This is something that I don't know what to call, so I named it "unwanted seam"

We figgled a lot with the Z seams in different places and depending on the model. If the model has a lot of corners we print with Z seam at random places and if it has smooth surfaces (like that bag handle) we print the Z seam at the same Z coordinate for each layer.

I can't figgure out why that "unwanted seam" is appearing. The weird thing is that when I printed the coat hanger (with the Z seam coordinate placed randomly at each layer) the same effect appeared.

[gr5 2,271]

well I don't know s3d very well but isn't there a "slice view" or similar so you can see what's going on at that darker line? I'm guessing maybe the infill is visible? Because this is a translucent material. But you would know better than I as you have the slicer and the gcode. Gcode can also be visualized by other software such as repetier host which loads a gcode file and you can highlight each layer or each line segment one at a time and see exactly what is going on visually.

[Horia 0]

The slicer view didn't show anything in the area where the bulge apeared. In the picture with the coat hanger you can see that the infill is touching the inner perimeter at a different point that the bulge is.

[tinkergnome 927]

Is this from the slicer or the printer?

 

I'm pretty sure that's the slicer. You can make a short test with another slicer, print and compare the result - just to be sure...

It looks like the opposite of a "z-scar". If you look at the preview (single layer view) - the seam is probably exactly at the layer change position.

Related settings in Simplify3D are:

- layer change position

- retraction restart distance

- coat distance

- wipe distance

...and the retraction options on the "Advanced" tab.

[Horia 0]

I found the culprit: acceleration

The left one is without accel and the right one with accel

It's a firmware problem, but I can't print without acceleration because my print time will be x5

Any idea how to fix this?

Edited March 1, 2016 by Guest
update

[gr5 2,271]

Acceleration? I don't know what that does.

The marlin firmware has an acceleration parameter for XY axes. It defaults to 3000 mm/sec for typical UM2 printer but can go up to 9000 mm/sec. You can override this in gcode but cura never messes with this. If this is an s3d parameter it should be more than a boolean - it should have a range of options. Typically I high acceleration can give you some subtle vertical lines on your print caused by "ringing". Usually 1000mm/sec gets rid of most ringing.

But I suspect this S3D parameter is something completely different.

[Horia 0]

After fiddling around with the  Jetty-Kubicek-Newman values and the acceleration from the machine we eliminated almost all of the bulge.

Edited March 2, 2016 by Guest

[gr5 2,271]

Nice! what did you pick for K and K2? What kind of printer do you have?

[Horia 0]

Nice!  what did you pick for K and K2?  What kind of printer do you have?

 

We have a FlashForge Creator PRO

The default values were k=0.005 and k2=0.055

The values that worked for us were k=0.0065 and k2=0.065

The default acceleration was about 1000 and we set ours to 500.

Edited March 3, 2016 by Guest

[Horia 0]

Update:

After a lot of tests and calibration we found out that there is inconsistent movement to the X and Y rods.

This could be because of bearings or belts. Don't know yet.

Saw on a lot of forums that the movement should be "smooth" for the carriage but we can't measure that. Probably we have to disassemble each component to find out what makes the hiccups.

If anyone encountered the problem and resolved it please help.

[gr5 2,271]

This friction is probably unrelated but should be fixed anyway.

Is this a UMO or a UM2. With the UMO the most common problem is that the end caps at the end of one of the 4 thicker horizontal rods is too tight. Try loosening 2 of them - on only one end of the 2 rods for that axis.

If this is a UM2 the most common issue is that the 2 axes are not perpendicular which causes problems in the bearings. This is easily seen visually if you look straight down.

There are other possibilities though - what kind of printer is this?

Oil the larger horizontal rods only - don't oil any rods that have linear bearings which includes the 2 X rods and the 2 rods that go through the heads. The other 4 rods definitely need a light oil.

Consider cleaning all the rods - put some protective cloth on the bed to keep oil off it then use oil and a cloth rag to clean all the rods. Remove all the oil from the 2 rods going through the head. WD40 is a good cleaner but keep it out of the bearings unless you remove the bearings completely and clean them separately - in that case WD40 is a good cleaner.

[yellowshark 153]

Just referring to @gr5 's post, my experience on WD40 is automotive based not 3D printer based. WD40 is a good cleaner but i leaves a residue, whether this is OK for printing I know not. Last year in the UK they released a range of new products and I think the new WD40 now does not leave a residue (i.e I read that somewhere); whether there is any old WD40 left in the distribution channels, again I know not. I just wanted to make you aware; I am sure though that if George has used WD40 on his printer then it will be OK

[eldrick 65]

If you use Kisslicer, you can specify where you want the seam to be placed (or use truly random placement).

Edited March 12, 2016 by Guest

[Horia 0]

My printer is a FlashForge Creator PRO.

I will buy a Motip PTFE lube (recommended by other makers) and grease the rods after a thorough clean.

[yellowshark 153]

Yup I a sure PTFE is the magic acrynom for not leaving a residue.