Jump to content
Ultimaker Community of 3D Printing Experts
jeroenm

Thick walls not touching

Recommended Posts

Hello,

Recently I encounterd a problem with my UM2 and nGen (probably also PLA) with thick walls. I'm designing some mechanical parts which need to be strong and light therefor I want to print them with 20% infill and 2mm (6x0.4mm) outer walls. But when printing with nGen I saw that the outerwalls where not touching eachother, so I did some googling and found that it probably some underextrusion.

here you can cleary see the prolem with the inner and outer walls.

IMG_9596_DxO.thumb.jpg.310cbccc8230b80285ddfadcf7b7d115.jpg

Printed at:

Cura 2.1.2

0.2mm

220C print

83C bed temp

100% flow

30% fan

Print speed: 60mm/s

Travel speed: 150mm/s

So I downloaded some test objects like 3D Benchy and UltiArjans temperature test for nGen.

The results from the UlitArjans test where pretty good:

IMG_9611_DxO.thumb.jpg.abc1b1895543de062e6774d35daeca3a.jpg

Than I printed the Benchy boat with Cura 2.1.2 in normal setting

0.1mm

220C print

83C bed temp

100% flow

30% fan

Which gave the following result:

IMG_9598_DxO.thumb.jpg.0f40c7f951f5cad3ef5f2bcca1ceeec0.jpg

IMG_9605_DxO.thumb.jpg.2b605236ef220d57a9b72738a9ac7a81.jpg

IMG_9603_DxO.thumb.jpg.d22d9c596fb857f76efaf6b7286b30ab.jpg

In the last picture there are some small signs of the wall problem.

I than draw a ring of 50mm with 1.6mm wall, which gave the following result:

IMG_9592_DxO.thumb.jpg.b5ba65192924e947f9f0ecbdae53fe8f.jpg

IMG_9594_DxO.thumb.jpg.407bed4a8cce20ec18d23539c97c959d.jpg

From all the objects the walls from the outside seem very nice, but are not touching eachother.

What can I do to fixs this problem?

Already checked the belts, cleaned the olson block and nozzle, the coupler has been replaced by the 3DSolex FT255C Coupler.

IMG_9596_DxO.thumb.jpg.310cbccc8230b80285ddfadcf7b7d115.jpg

IMG_9611_DxO.thumb.jpg.abc1b1895543de062e6774d35daeca3a.jpg

IMG_9598_DxO.thumb.jpg.0f40c7f951f5cad3ef5f2bcca1ceeec0.jpg

IMG_9605_DxO.thumb.jpg.2b605236ef220d57a9b72738a9ac7a81.jpg

IMG_9603_DxO.thumb.jpg.d22d9c596fb857f76efaf6b7286b30ab.jpg

IMG_9592_DxO.thumb.jpg.b5ba65192924e947f9f0ecbdae53fe8f.jpg

IMG_9594_DxO.thumb.jpg.407bed4a8cce20ec18d23539c97c959d.jpg

Share this post


Link to post
Share on other sites

Stick with the simplest test part. That ring looks great as you can make adjustments while it's printing. Try printing at 1/4 speed first and at 240C and up flow to 120% just to prove that it's really underextrusion. the difference from 215 to 230 while significant, is probably too small to see without really looking carefully. If you are getting this with the ring it is almost certainly underextrusion which can have dozens of causes. Here are a few - read every one and try to be very sure before you eliminate them one at a time:

CAUSES FOR UNDEREXTRUSION AND HOW TO TEST FOR THEM AND REMEDY THEM

As far as underextrusion causes - there's just so damn many. none of the issues seem to cause more than 20% of problems so you need to know the top 5 issues to cover 75% of the possibilities and 1/4 people still won't have the right issue. Some of the top issues:

1) Print slower and hotter! Here are top recommended speeds for .2mm layers (twice as fast for .1mm layers) and .4mm nozzle:

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. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA.

2) Shell width confusion. Shell width must be a multiple of nozzle size. For example if nozzle size is .4mm and shell width is 1mm cura will make the printer do 2 passes with .5mm line width which is possible but requires you to slow down much more to make a .5mm line out of a .4mm nozzle. If you really want this then set nozzle size to .5mm so it's clear what you are asking Cura to do for you.

3) Isolator - this is most common if you've printed extra hot (>240C) for a few hours or regular temps (220C) for 500 hours. It gets soft and compresses the filament under pressure. It's the white part touching the heater block. It's very hard to test when not under full pressure (spring and bowden) so sometimes it's best to just replace it. Also if you notice parts of it are very soft (the blacker end where it touches higher heat) then it's too old and needs replacing.

4) Curved filament at end of spool - if you are past half way on spool, try a fresh spool as a test.

5) curved angle feeding into feeder - put the filament on the floor -makes a MASSIVE difference.

6) Head too tight? Bizarrely MANY people loosen the 4 screws on the head by just a bit maybe 1/2 mm and suddenly they can print just fine! Has to do with pressure on the white teflon isolator.

6b) Bowden pushing too hard - for the same reason you don't want the bowden pushing too hard on the isolator.

6c) Spring pushing too hard. Although you want a gap you want as small as possible a gap between teflon isolator and steel isolator nut such that the spring is compressed as little as possible.

7) clogged nozzle - the number one problem of course - even if it seems clear. There can be build up on the inside of the nozzle that only burning with a flame can turn to ash and remove. Sometimes a grain of sand gets in there but that's more obvious (it just won't print). Atomic method (cold pull) helps but occasionally you need to remove the entire heater block/nozzle assembly and use flame. Or soak it in acetone overnight (after removing 90% of the material with cold pull).

8) Temp Sensor bad - even the good ones vary by +/- 5C and bad ones can be any amount off - they usually read high and a working sensor can (rarely) fail high slowly over time. Meaning the sensor thinks you are at 220C but actually you are at 170C. At 170C the plastic is so viscous it can barely get out of the nozzle. You can verify your temp sensor using this simple video at youtube - on you tube search for this: mrZbX-SfftU

9) feeder spring issues - too tight, too loose

10) Other feeder issues, one of the nuts holding machine together often interferes with the feeder motor tilting it enough so that it still works but not very well. Other things that tilt the feeder motor, sleeve misaligned so it doesn't get a good grip. Gunk clogging the mechanism in there.

11) Filament diameter too big - 3mm is too much. 3mm filament is usually 2.85mm nominal or sometimes 2.9mm +/- .05. But some manufacturers (especially in china) make true 3.0mm filament with a tolerance of .1mm which is useless in an Ultimaker. It will print for a few meters and then clog so tight in the bowden you will have to remove the bowden from both ends to get the filament out. Throw that filament in the trash! It will save you weeks of pain

11b) Something wedged in with the filament. I was setting up 5 printers at once and ran filament change on all of them. One was slowly moving the filament through the tube and was almost to the head when I pushed the button and it sped up and ground the filament badly. I didn't think it was a problem and went ahead and printed something but there was a ground up spot followed by a flap of filament that got jammed in the bowden tube. Having the "plus" upgrade or using the IRobertI feeder helps you feel this with your hand by sliding the filament through the bowden a bit to see if it is stuck.

12) Hot weather. If air is above 30C or even possibly 25C, the air temperature combined with the extruder temperature can soften the filament inside the feeder such that it is getting squeezed flat as it passes through the feeder - this is obvious as you can see the problem in the bowden. The fix is to add a desk fan blowing on the back of the printer. Not an issue on the UM2 "plus" series.

13) Crimped bowden. At least one person had an issue where the bowden was crimped a bit too much at the feeder and although the printer worked fine when new it eventually got worse and had underextrusion on random layers. it's easy to pull the bowden out of the feeder end and examine it.

14) Small nozzle. Rumor has it some of the .4mm nozzles are closer to .35mm. Not sure if this is actually true. I'm a bit skeptical but try a .6mm nozzle maybe.

15) CF filament. The knurled sleeve in the extruder can get ground down smooth - particularly from carbon fill. 4 spools of CF will destroy not just nozzles but the knurled sleeve also. Look at it visually where the filament touches the "pyramids". Make sure the pyramids are sharp.

  • Like 1

Share this post


Link to post
Share on other sites

Excellent! Note that you won't get as beautiful overhangs at 240C but if you are in a rush and/or don't have any significant overhangs then stick with 240C. Personally I have several printers and usually not in a rush so I just print slower or use a larger nozzle.

Share this post


Link to post
Share on other sites

A friend of mine tested with his UM2 and UM PLA and the same 3D model, which showed the same result:

WP_20161019_09_27_58_Rich.thumb.jpg.4b89fc545d0f7a675c8c5f81379a2d44.jpg

If we use single walls there is no issue at all but with multiple wall thickness we have issues also with cura 2.3.0

I printed some model with 240deg but the fhinis was not very nice. Als setting the flow to 120% should not be normal, it is more a patch the fixing the source of the problem.

WP_20161019_09_27_58_Rich.thumb.jpg.4b89fc545d0f7a675c8c5f81379a2d44.jpg

Share this post


Link to post
Share on other sites

Yes - this is much clearer - this is underextrusion. It can have many causes most of which I listed above.

220C .2 layer height 60mm/sec as you mentioned above is really right at the limit of what an UM2 can do. The pressures in the nozzle are at an extreme - about 100psi. The pressure on the filament is about 10 pounds or 5kg. Trying to push that hard by hand would lift the printer off the table. I recommend never going over 30mm/sec at that layer height and temperature. At that extreme you really need to increase the flow a bit because the filament is slipping a consistent amount in the feeder. I know you said you saw the same problem but not as bad at 0.1mm layer height which makes sense as you are at half the printing speed, half the nozzle pressure.

Increasing the flow is a reasonable solution although I have found that when you get to where you need 140% to get no gaps in walls you are at the point where going any faster will just grind up the filament to dust. If 120% is enough then I would just keep using this flow rate for this color and brand of filament. This is not a hack solution but an excellent solution.

Another solution would be to get a bondtech feeder. It pushes from both sides of the filament instead of just one side and can go to probably about 100mm/sec before needing 120% flow.

If you really want perfect looking parts you are going to have to slow it down anyway for other reasons.

A better way to speed things up would be to go with a larger nozzle. A 0.6mm nozzle can print double the volume of filament in the same amount of time. The loss in XY resolution by gonig from 0.4 to 0.6 is pretty small. The outside radius of a corner on a cube will be 0.3mm instead of 0.2mm. Circular parts will be just as good/perfect as with 0.4mm nozzles. Benchy will look just as good because all his corners are rounded already.

Share this post


Link to post
Share on other sites

Thanks GR5 for the tips again, I will try some test prints with different speeds to see what is the impact. What I did in my last test is first took the normal settings in cura and than copied them to the advanced settings and changed the layer height.

I never stood still by the fact that a higher layer height with the same speed needs a higher extrusion rate.

The bondtech feeders look nice, but rather expensive :p

Share this post


Link to post
Share on other sites

The problem seems clear to me. Cura has more than one speed. It has separate speeds for outer shell, inner shell, and infill. Somehow your inner shell seems to be printing too fast as I can see the outer two shells are touching nicely and the infill looks solid but the inner two shells are probably both a little underextruded (printed too fast).

So go into the more advanced settings in cura. 15mm/sec is crazy slow. Try this:

35mm/sec (all printing speeds - travel speed should be 150-300mm/sec), .2mm layer height, 220C.

ALTERNATIVE EXPLANATION: make sure your shell width is an integral multiple of your nozzle size. so if nozzle size is .4 and you want three shells than shell width must be 1.2. If you make it 1.3 you can get underextruded shell.

Share this post


Link to post
Share on other sites

I just printed a new test with 30mm/s for infill and wall and top/bottom at 15mm/s at 0.1mm height. I set the wall line count to 4 in cura 2.3.0 and 100% infill

Btw I just ordered a bondtech :p

Edited by Guest

Share this post


Link to post
Share on other sites

Yesterday I received my bondtech 3.0 QR UM2 kit and new bowden tube somehow I ordered the wrong lenght but they put in right one for the UM2 :). The built quality looks perfect, and very robust. Olny had some problems after the first print with strange behaving motor, but they emailed me that is was probably the wiring. Which was correct some how it came loose.

I did the extreme exstursion test found on the forum with the U2RS feeder:

Extrrusion_test_U2RS_feeder.thumb.jpg.2ceefe159c610bcf4bc93da27275d801.jpg

As you can see from 10mm/s issues start to appear.

Than I replaced it with the Bondtech extruder and cleaned the complete print head and did the test again:

Extrrusion_test_bondtech.thumb.jpg.723cbeaf8e173059e76929e6c165d254.jpg

No issues at all

Than I printed my test part again with max 30mm/s and the bondtech:

0dot20mm_30mms.thumb.jpg.23ef0e9fe8c39c36eff2da5f2c09f215.jpg

It seems to be better but still there are some gaps.

I'm still wondering if it is an under extrusion problem and not something else.

Would it be possible for you @gr5 to print the part as well on your printer ?

GCODE

Extrrusion_test_U2RS_feeder.thumb.jpg.2ceefe159c610bcf4bc93da27275d801.jpg

Extrrusion_test_bondtech.thumb.jpg.723cbeaf8e173059e76929e6c165d254.jpg

0dot20mm_30mms.thumb.jpg.23ef0e9fe8c39c36eff2da5f2c09f215.jpg

Edited by Guest

Share this post


Link to post
Share on other sites

I forgot you were printing nGen and not PLA when I said 60mm/sec at .2mm was too fast. I don't know how different nGen viscosity is versus PLA so it could be that even 30mm/sec at your printing temp is too fast. Maybe you need to increase the temp.

I looked at your gcode file with the website: gcode.ws and I can see that your outer wall at 15mm/sec is 2X slower than inner walls. I recommend you print all at one speed to get more consistent quality. But you have to decide on strength versus speed tradeoffs.

I'm too lazy to get off my butt and get the UM2 out of the basement. Lately I've been using only my UM3 and my um2go. But I need to print something else on the UM2 this weekend so maybe I'll print your part also. Using nGen. What temperature are you printing nGen?

Unrelated - note that colorfab recommends 50% fan speed on ultimaker 2. I hope you are doing that. If not you may have very weak layer bonding which is difficult to notice unless you purposely stress your part until it breaks. If it breaks along layer lines then you need to lower the fan and/or put a front cover on your printer.

a.thumb.png.3050a1322ad099e2cbeb3f914e6b1c3e.png

a.thumb.png.3050a1322ad099e2cbeb3f914e6b1c3e.png

Share this post


Link to post
Share on other sites

I printed indeed with nGen, now testing with PLA/PHA.

I printed with 230 degree and 83 bed with air flow of 50% as recommended by colorfabb.

Let me know if you were able to print it with UM2 or just UM3.

Thanks again for all the help

Edited by Guest

Share this post


Link to post
Share on other sites

Printed just fine.  I printed your gcode. This is ngen at 230C bed at 80C.

sorry my pictures aren't as clear as yours.  This is a small part. Click on second/middle image to see more details. It does look like possibly a little underextrusion (dashes of gap maybe?). Hard to tell.

5a33232ad16bb_2016-10-2913_36_07.thumb.jpg.ba7509df9b7a33a42e8da3eb2160a96f.jpg

5a33232ab4199_2016-10-2913_40_49.thumb.jpg.3aee3831d253f1011b758c9729904a29.jpg

5a33232a1ed46_2016-10-2913_36_07.thumb.jpg.6d1d5ba3061f106ea5add9f98b6f097f.jpg

5a33232ad16bb_2016-10-2913_36_07.thumb.jpg.ba7509df9b7a33a42e8da3eb2160a96f.jpg

5a33232ab4199_2016-10-2913_40_49.thumb.jpg.3aee3831d253f1011b758c9729904a29.jpg

5a33232a1ed46_2016-10-2913_36_07.thumb.jpg.6d1d5ba3061f106ea5add9f98b6f097f.jpg

Edited by Guest

Share this post


Link to post
Share on other sites

This was with bondtech. I was asked to test out the bondtech - if I wasn't always asked to test feeders I'd still have the original black feeder on there which I think worked good enough for me.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Our picks

    • Taking Advantage of DfAM
      This is a statement that’s often made about AM/3DP. I'll focus on the way DfAM can take advantage of some of the unique capabilities that AM and 3DP have to offer. I personally think that the use of AM/3DP for light-weighting is one of it’s most exciting possibilities and one that could play a key part in the sustainability of design and manufacturing in the future.
        • Like
      • 3 replies
×

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!