Bad surface quality

[warderoid 0]

Hi all,

Maybe you can help me.

Over the past few weeks / month our U2 has lost its mojo, and prints are looking pretty poor quality :(

I got a print done on a friends U2 and it was flawless, which makes me think mine has been on a downward path for a while now. Well, I cannot accept it anymore!

I used grease and all axis move freely, and the z axis the same. no dry spots, I can move the head around freely with a few finders, and the bed simply up and down with two hands!

My belts don't appear to be any looser or worn than those on the other (newer) machine I tried today.

I did think some of the issues were extrusion, I took apart the extruder and cleaned it all out. The knurled gear thing was fine. I have run the same print several times with different adjustments to the tension but all seem to print OK till I commit to an actual part and then it may under extrude. one print in particular repeatedly failed yesterday.

Any suggestions / requests for more info??

Thanks

Edited May 14, 2015 by SandervG

[gr5 2,172]

It won't let me look at the picture without creating a "one drive" account. Not interested, sorry. Please don't make me do any extra work. You can post here by starting a reply, then clicking right most icon, then second tab, then drag and drop an image onto the window.

[gr5 2,172]

By the way I'm going to guess underextrusion. Try printing 10C hotter and at half your normal speed and see if it gets much better.

[gr5 2,172]

Consider printing this at 230C:

https://www.youmagine.com/designs/test-print-for-ultimaker--2

It must be done at 230C for a valid comparison. This test only works if your extruder skips - some of the newer UM2's rarely skip anymore - they tend to slip quite a bit before skipping. There are better tests but they are more complicated.

[warderoid 0]

OK, will print that when I can / print an object hot and slow.

Thanks for the prompt reply.

Edited May 12, 2015 by Guest

[gr5 2,172]

 

@warderoid - the main point is we need to see a photo. Usually I think I understand the poster, but then I see a photo and have to completely reverse every suggestion I made.

[titanoid 4]

How many hours of printing has your machine done?

Perhaps the PTFE coupler (hotend isolator) is worn out.

There are photos of isolators in various states of destruction somewhere inside this forum, still can't find them at the moment, sorry!

[warderoid 0]

I spent today cleaning the hot end, there was a lot of grotty filament in there - presumably from woodfill. The filament was really jammed in there, and wouldn't get anything through.

A video of the Ultimaker bed being a bit....wobbly

 

image here

I just have another print on at the moment - simple tube models.

This one isn't as bad, as it was from some time ago, also the material hides it quite a bit

Edited May 14, 2015 by Guest

[swordriff 119]

Woodfill needs retractions OFF. No pause in printing, it must flow all the time.

There is more moisture inside than in many other filaments.

This gets cooked and if you have to much retractions/ too slow speed/ too high temp it will turn into chewing gum in your hot end!

Woodfill: 120-135% material flow. Speed 50-80mm/s. Temp 220-225 to get it stick on hot bed,

then I lower to 215 and it goes on without problems!

[shurik 87]

I printed with the woodfill on 100-105%, 50mm/s, 210C with no visible problems. The retractions were ON. No complicated models were printed, though.

Yes, the hotend needs a very good atomic cleaning after the prints, for sure.

[warderoid 0]

I have had some prints come out OK with the woodfill, I guess this time round it put up a good fight! Certainly experienced the chewing gum you described!

I checked the printer stats and its on 800 hrs print time.

Also, the left most belt, driving the y axis is a bit slack compared to the others. Will tension and report back.

[gr5 2,172]

Looking at that photo of the orange part - it tells me many things.

You x,y,z looks perfect. Don't bother with the Y belt - it's fine. However you have underextrusion (pretty severe - maybe 50% of the filament requested) in the lower third.

There's lots of things that can cause underextrusion.

Your nozzle may need many atomic pulls after printing woodfill. Or other possibilities. Here are top recommended speeds for .2mm layers (twice as fast for .1mm layers):

20mm/sec at 200C

30mm/sec at 210C

40mm/sec at 225C

50mm/sec at 240C

The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion.

If you are printing at these speeds/temps/layer height and seeing this kind of major underextrusion then something is wrong and we can move on to possible solutions and tests (other than cleaning nozzle which is only one of about 20 things that can cause underextrusion - the next most likely would be your ptfe isolator).

[warderoid 0]

Printed at 20mms at 200

[warderoid 0]

Printed at 20mms at 200 0.2mm layer height

Edited May 15, 2015 by Guest

[Dim3nsioneer 557]

Maybe you want to check out this thread. Luckily the pictures seem to have survived porting from the old to the new forum.

[gr5 2,172]

Waderoid - clearly the blue cube has no underextrusion. Yet the orange part earlier did. So you likely printed them at different layer height, temp, or speed.

Are you trying to make a point about the horizontal lines on the cube? Those are unrelated to the underextrusion on the orange part. Not sure if you want to "fix" this - if you do then maybe start a new topic.

[warderoid 0]

Hey - yeah thanks for the help. I did start the thread assuming I needed help with the surface quality - but then it turned into an under extrusion thread!

The blue cube as you rightly said is showing no signs of under extrusion, so the nozzle was clearly the culprit of that. I have since printed out two of the belt tensioners found on Thinigiverse and my surface finish has returned to the good old days of straight as an arrow. (well, certainly within acceptable range!)

As the quality has improved with the belt tensioners, can I assume that I need to replace them / all to get rid of all surface artefacts??

The replacement belt pack on the ulti store look say they are for the UM original only - do I have to contact support direct to order for the UM2??

Thanks again.

[gr5 2,172]

The UM2 shouldn't need belt tighteners - there are belt tighteners *inside* the blocks. But they only tighten one side. To get the tension to travel to the other side you have to loosen the pulleys and let the tension distribute and then retighten.

The belt tighteners inside the um2 blocks are basically the same springs one finds on a clothes pin.

I thought the umo and um2 had the same belts but I'm not sure.