UM2+ started to cornerlift after a few years of perfect print

[philippe44 0]

Hi - I have an UM2, upgraded to 2+. The original version caused me some issues with the feeder but since the 2+ upgrade, it worked perfectly. Then, a few weeks ago, it started to do corner lift on all my prints. I've checked bed T° and leveling multiple times, used different material, no luck. It does not look like there is under-extrusion. I've re-read different advices here and there, but could not find anything that would fix the issue. I've added a couple of picture (there is another issue with last layers, but please ignore it) in case somebody here can provide better wisdom

[Torgeir 228]

Hi @philippe44,

 

Well, I'm used to adjust the bed often, but sometime less often.

The bed is cleaned by using a scrape, a small one normally used to remove paint from windows..

If I'll forgot to do this for too long, my print will start to lift off the bed, because it start crimping at the top and will soon snap off the bed because of poor adhesion.

 

So first thing, make sure you've marked the up side of the bed (I'm using a permanent marker) , clean the bed with a scrape, then wash with "hand warm" soapy water, if you've printed some "nasty" filament you might need to use alcohol/isopropanol as well. After the "bath" of the bed, rinse well with tempered water and dry it. Avoid finger print on the print side..

 

Next is to do a bed adjustment, remember the (Z) height micro switch and the mechanical parts do wear a little over time and also -might need some lubrication.

 

I'm using a note from an ATM as a space (height) detector. When starting this adjustment, firmware ask you to adjust to approx 1 mm the inner mid position by using the wheel knob. Then to do the same on first outer R/H corner and lastly L/H corner -for both adjustment here using the turn knob under the bed..

 

Round two is to be done withe the "note from the ATM", the inner mid point with the wheel knob -here just one notch will release the ATM note -if so you made a very good adjustment! Next in same order as above, using the note and the turn knob under the bed. During this adjustment it is easy to push or pull the knob so the adjustment will be in error, so remove your finger from the knob in between adjustment to make sure your adjustment is good.

 

Sometimes I've seen that the 110% first layer feed is to much, so I'll adjust it to 100% to make a clean and even first layer.

This might not be an issue for anyone, but might be something for some..

 

Good luck

Thanks

Torgeir

 

 

 

[geert_2 557]

My first thought was: "dirty glass". If you clean it with soap or window cleaner, be sure to clean it again afterwards with pure warm tap water only. Best twice. Thus no more soap. The reason is that soap reduces bonding too. So you really need to remove all traces of soap and detergents. Don't ask how I know this.  :-)

 

After a closer look at your photos, it looks like the bottom "sausages" are quite round, not very much squeezed into the glass. That could also reduce bonding. So, in addition to cleaning, I would also check bed leveling, and bring that closer if necessary.

 

Also check if you don't have underextrusion, thus too thin sausages, which could cause the same effect: the print not squeezed into the glass very well, but now due to lack of material, instead of the glass being too far away. If you have twice the contact area per extruded sausage, then you have twice the bonding strength.

 

The bottom of my prints usually looks like this:

 

 

 

[philippe44 0]

Thanks both of you for your answers. SO far I've changed the bed to 55° and it a bit better, but I think you're right, there is likely some under extrusion, now I need to figure out why (bring back bad memory from my UM2)... I've just checked feeder and even replaced the motor with a spare that I had for a while (original 2+ issue with sliding gear that I glued, now it's a motor with a notch on the axis), so new gear & motor, same result, I need to look elsewhere.

 

Meanwhile, another question: from time to time my print seems to miss badly X position after a couple of layers and give that. You can see that after the 1st (or a few layers, the whole print is offset alongside the X axis. Have you ever seen this?

 

 

[Torgeir 228]

Hi @philippe44,

 

this is for sure a hi number of missed step or a loose pulley on X stepper motor.

If the stepper loos steps there will be a high clattering noise, but if a pulley is loose there is not much noise, -except if the nozzle head might slam into the side wall and this is noisy..

Also if there is too little lubrication the X shaft parts, due to this the friction might increase and lead to missed step plus offsetting your print object.

 

So if there is not much noise when this happens, check that if the pulley is not "loose" on the X stepper motor *) and that the adjustment of the pulley position on the shaft is correct. If adjustment is required, be sure to tighten the set screw with very good torque when in position. (A poor quality Umbrako (hex) toolkit should not be used for this issue.)

 

*) The X stepper motor is located inside upper right side of the printer-

 

Use Ultimakers assembly manual as reference, found here:

https://github.com/Ultimaker/Ultimaker2/blob/master/um2 assembly manual V1.1 _english.pdf

 

PS. I always use 60 degrees Celsius on the bed when printing with PLA. If the room temperature is a little on the low side, a "cold" airflow to the upper part of the print object can cause shrinkage which can detach the model from the bed.

But definitely, follow the manufacturers' recommendation for the filament type.

 

Good luck

Thanks

Torgeir

 

 

[philippe44 0]

Thx - I've re-secured the pulley and will see - one was a bit (not much) loose.

 

Re corner lift, I don't know what to do anymore. I've put a brand new reel of PLA, replaced the teflon insulator (was a bit damaged at the hot end), the nozzle and, as said before, put the spare motor feeder I had. No change and, for example, if I print 5 spread copies of an item that is the size of a SDcard holder, the lift is about 0.5 to 1mm on each angle of each copy. The first layer also seems to be well flat and shiny, as before, so "sausage" effect. It seems to point out to a bed issue, but I've verified T°, it's even and as requested.

 

Looks like my well-behaved UM2+ is reaching some sort of end.

Edited February 8, 2021 by philippe44

[Torgeir 228]

Hi @philippe44,

 

you sure need to indicate which pulley was found loose, -without this info it's impossible to verify the fault.

A picture of the objects location inside the printer when the "missed steps" occurs is also a good for understanding the failure.

So picture of the pulley and picture of the faulty print object when they're still on the bed says more than a thousand word.

A project file of what you're printing may help -as a slicing error can make your printer become like look faulty..

I'll think your first layer is good!

Trying to change too many thing right away is not the way to go, as if it's become OK., you never will be sure what was real thing that's failed.

An UM2 is not possible to wear down, actually a small amount of routine maintenance, -will keep this printer last much longer than most other printers there is!

 

Thanks

Torgeir

Edited February 9, 2021 by Torgeir
Text error.

[philippe44 0]

Hi @Torgeir - I agree with doing incremental changes so that you can draw a proper correlation and this is what I did. I was just giving the summary of all cumulated changes. BTW, the "missed steps" is not my biggest concern for now as it does not happen very often, the corner lift is really what I'm trying to solve as it is really ruining prints. I can do a raft but this does not give the same finish and it was not needed a couple of month ago, so I really want to understand why.

 

I do like my UM2+ but I had mixed experience with it. I bought it as a UM2 and it worked fine for a while then it started to under-extrude and for the life of me I never figure out why. I've tried every feeder mod, filament guide tool and other things till the 2+ kit came around. With that kit, it went back to perfect printing for a long while and then it derailed again. I also have a FlashForge Creator Pro2 and what is "sad" is that the UM2+, when it prints, has a *much* better quality than the FFCP2 but the FFCP2 has been *very* consistent in printing results where my UM2/2+ has been *very* temperamental, so it's frustrating.

 

[geert_2 557]

I may have missed it in the posts above, but I didn't see what bonding method you used? Could you describe that, thus method-name and exact procedure? That could be a reason too for the warping? Also describe the cleaning method you use for the glass? And the weather conditions in your environment now, temperature and moisture-level? These all play a role too in bonding, in addition to bed-distance and underextrusion.

 

Since it isn't solved, it is best to go over each step again.

 

For underextrusion: on my older UM2 (non-plus), there are a couple of things that are likely to cause underextrusion:

- When the teflon coupler is worn-out: if you do an atomic pull, and there is a thick sort of ring or blob at the edge between coupler and nozzle, then it is worn-out and needs replacement. See the pics below.

- When the filament spool is nearly empty, especially when printing hard filament like PLA: the hard filament acts like a strong spring, that resists unwinding. If you have a very hard time unwinding it by hand, then the feeder has so too.

- When printing in the back-left corner: then the filament has to make a very tight curve in the bowden tube, and this causes a lot of friction in the nozzle and bowden tube.

- When the nozzle is partially clogged by accumulated dirt and coal on the inside of the opening. Regularly do a cold pull to keep it clean.

- And obviously, when all the above are combined.

 

There could be lots of other reasons too, such as incorrect filament diameter, or dirty feeder wheels or damaged feeder, but the above I found the most common for my system. User gr5 has a good list of causes of underextrusion, so try to find that.

 

As bonding method, for PLA (not for other materials) I only use my "salt method": after thoroughly cleaning the glass, I put a few drops of salt water on it, and wipe that with a paper tissue until dry, so it leaves a very thin mist of salt on the glass, almost invisible. This greatly improves bonding compared to printing on bare glass. When printing on bare glass, the results are very dependent on circumstances: it may bond reasonable well in very dry weather (like freezing cold), but it may not bond at all in moist weather.

 

The salt method works very well for me on long and low models, like rulers, at 100% infill: they stick like rock. But not so good for thin and high models like lantern poles: these might get knocked over.

 

Have a look at my salt method, and my gentle atomic pull method here:

https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

 

Pictures:

 

1. If you think friction due to the end of the spool being wound too tight, and too hard to unwind: manually unwind a bit,  and wind it in the opposite direction around a skater wheel, thus bend it in the opposite direction. Then let go and do the next part. So it sits very loose on the spool, has the same bending-radius as the bowden tube, and causes almost no friction and no resistance when unwinding and transporting through the tube and nozzle.

 

2. These kind of long low models print very well using the salt method: I have done many hundreds without any problem.

 

3. The thick sort of ring or blob in the white filament after an atomic pull, indicates that the teflon coupler is completely worn-out.  When printing, half-molten filament gets stuck in that widened area, and causes underextrusion.

 

It should look like the orange one at the bottom here: totally straight. The other two were pulled-out a bit too soon, before the filament had completely solidified. Obviously, these were all done while changing color, to remove remains of the old color from the nozzle. Also check if the cone-shape is good, like here.

 

[Torgeir 228]

Hi @philippe44,

 

for your printing problem, -you hardly find any better advice than @geert_2 have listed here..

 

Thanks

Torgeir

[philippe44 0]

Thanks very much for your long and detailed answer. I've eliminated end of spool, nozzle, leveling, teflon coupler, position on the bed. 

 

With regard to bounding method, I used to just print on glass when it was working fine. On rare case, I added hair lacquer. To clean glass, I use 99% alcohol then soap water and checked with a finger that it is dry & non-oily. 

 

I will look at the salt method, thanks a lot!

[geert_2 557]

For cleaning, don't use soap: that reduces bonding. That could well be the reason for your warping. Or do it the other way round: first soap water (like window cleaner or Mr. Proper), then isopropyl alcohol, and then with pure handwarm tap water only (but no soap). After using alcohol, don't touch the glass anymore on the areas where you are going to print. Finger-grease also reduces bonding.

 

Also very moist and rainy weather might reduce bonding, when printing on bare glass. That is why I started searching for a new method, the salt method.

 

[philippe44 0]

So... that's it. I'm giving up on my UM2+, it is too frustrating. It will be for sale tomorrow (a good deal out of anger 😁). I spent hours on a new design and adhesion is randomly at best. On my FFCPRO, the quality of the print is far less, but the surface is totally flat. I want to do designs and print them, not to spend hours messing with the printer itself (I understand that sometimes the fun can be in fiddling around with the device, that what I tend to do with my telescopes, but not here). We had a few good years with this UM2+, but it's over now.

 

Sorry for just venting, but you know what it is when you wake up and see that a 16 hours job is messed up after 6 hours of printing.

Edited July 26, 2021 by philippe44

[philippe44 0]

I decided to run some more systematic tests to tell the buyer of my UM2° what to expected.

 

One interesting thing I missed (...) is that I have a clear different between left and right side of the bed. I've printed a simple square on 20*10*1.5, duplicated 2 cm away from borders and it sticks on the left and lifts like crazy on the right. The bottom layer is well flatten on the left and stays round on the right. I know (I know) it sounds like bed leveling, but I can guarantee that I've leveled it 10 times and it's consistent right and left. I have turned the glassbed upside down, same result. Another (less surprising) thing is that adhesion is better at 0.2 mm thickness and is a disaster at 0.1. I assume it's because upper layer pull more at 0.1.

 

Any idea why I have this dissymmetry?

[Torgeir 228]

Hi @philippe44

 

Have you checked that the two 6 mm axes are clicked in place to the four plastic holders -and are not loose?

This can make your adjustment faulty..

Also, there could be play in between the head bearings and the axes at different places on the bed.

 

Thanks

Torgeir    

Edited July 27, 2021 by Torgeir
More text.

[viktor_b 1]

@philippe44

 

observing the same on a brand new UM S5. Printed a pattern of 4 parts approx 110x80x6 mm. Material ABS from BASF, used UHU glue, bed temperature as per datasheet. All four parts do have a lifted left rear corner. Wondering if it could be related to by air manager created air circulation inside the box.