Adhesion issues.

For some reason my normally well behaved Ender 3 pro has been trying to drive me crazy these past few days. I have been trying to print large flat surfaces and suddenly after having done the same prints many times I was now having problems.
I’m afraid I’m not a great fan of glue sticks unless I have some hair spray mixed in.
Because I was having so much trouble trying to stick large flat surfaces to the bed (my lamps) I pulled out Chep’s Bed level print and tried it with a clean bed with light glue stick and heated bed. It turned out a mess that I should have photographed. I gave a light coating of hairspray and got the results you can see for yourself. I can:t upload gcode files to this forum so you will have to get it from chep if you want to try it.

chep level test print.jpg

So right after this success I tried to print another lamp bottom and it failed. I am wondering if it is because I did the design in Tinkercad then sliced it in Prusa. I have tried to print it many times but it always lays down the botom left corner first and then starts going around the large square and nothing sticks. But the chep test worked perfectly just before. I really don’t understand.

Those lines are fine, but they do not represent a real world print.

In the real world print you have bigger surfaces and on the third or forth line to build these surface you will notice gaps between the lines at some points. It looks like lines are placed down with a little spacing next to each other, while it should be a connected surface.

This can have several reasons:

  1. nozzle to high (filament gets dropped like from an airship and even so the line sticks to the bed, it does not stick to the cold line already on the plate.)
  2. nozzle to low (filament of prior lines gets scraped of by the nozzle itself) (not the case here as it would not pass the chep test)
  3. under extrusion (the lines placed on the bed are not thick enough to connect to the parallel lines already on the plate. Result like #1)

First thing: Check your extruder gears. They may be full of filament dust and have not enough grip. It is always a good idea to use a paint brush or an old tooth brush on the gears to clear them out.

Then you should check the extruder calibration. Mark a section 100mm from the extruder away. Extrude 100mm (PronterFace or so) and check if the mark is about to enter the extruder. If it is more than a millimetre to short, you need a calibration of the e-steps. You could try to increase the first layer extrude rate in your slicer from 100% to e.g. 115% but this will only compensate the issue and not fix your setup.

If the extruder is set-up ok, then adjust your z offset. Your nozzle needs to be down a little. Change by 0.01 and retry until it works. Again you could increase the extrude rate in your slicer, but that will not fix the real issue and just works around it.

You have auto bed levelling, but that does no setup the z offset for you. The z offset depends on the long term temperature of the bed. The first print may fail and the second or third works, because the heat creaps into all corners of the bed over time. That is why I tend to turn on the bed, wait for it to reach the print temperature and then wait for around 10 to 15 minutes, before I start the print job. that way my first layer is always the same and not dependent on the room temperature or the last print attempt. Thats why I stack my prints inside OctoPrint. When I start printing I usually have at least three print jobs I can perform in a row without having to pre heat before each print.

Summery: Pre heat your bed and wait. If the print fails, lower the nozzle and retry until it works. When printing the next time remember to pre heat the bed before the first print and you will have less problems.

I know this is a lot for your brain to take in, but having a specific routine when 3d printing is key.

Maybe hang a little card on top your printer with all the steps required before pressing print. Like a pilots checklist. You and anyone already does that silently already, but sometime steps get forgotten.

Stuff like “Check if the print bed is free”, “Check if the print bead is clean.” “Check if the belts are ok and tight.” “Preheat bed and wait 10 minutes after it reaches print temperature.” “Check if the filament path is clear and the filament is not broken.”

Maybe some “first layer rules” list, so you always know what do do when a print does not stick.

These are just some examples for such list(s), but in the end they save a lot of time. I guess everyone here had issues in the past which would have been prevented by such a warning sign and a proper launch procedure. Maybe printing and designing a warning and takeoff sign is a nice 3d printing project, too.

I myself remember hearing a loud noise from my printers room, because I started a print remotely and the print head crashed into an old finished print I just had forgotten on the build plate. Just last week I started a print and after 60 minutes, when I checked on it, there was simply nothing. During maintenance and repair I removed the filament and forgot to insert it again. :slight_smile:

That’s all good advice that I am very aware of. I just had another print print for hours very nicely but when I woke up this morning it had suddenly plugged and failed and finished it’s cycle without extruding any plastic. I don’t need a heated bed to make my prints stick like shit to a blanket. Actually I do best with a mixture of glue and hair spray once in a while. This print was stuck firmly on a cold bed and printed for hours, before I went to bed, very nicely. My chep test was perfect when I did it my way and not the way everyone else does it with light glue and heated bed although I think the bed was heated in this test it makes no difference. The hair spray once in a while does the trick. My problem is in my hot end. My extruder works very well being a double and it has been calibrated a while ago. I would certainly consider buying another hot end even though I have four of them. Ijust don’t know which one I should buy, I nave an all metal extruder I might try but I don’t have much confidence in it, It leaked last time I tried it but I have some thermal goop that might fix that problem.

Most leaks are caused because the hotend needs to be assembled in hot state,

I haven’t had any leaks for months until the other day. I realize that you are trying to help me and I appreciate it but I’ve been through all this for nearly two years now. I have hot end heat creep. Usually my plugs take place high up on the hot end where the filament shouldn’t be heating yet. I get plugs as high as where the bowden tube connects to my hot end. I keep a separate piece of tube inside so that it can be jammed between the bowden connector and the tip so that it can’t leak and it works.

The point is doing that in “heated state”. Assembling in cold state may work for a while, but it will fail do to the material is expanding when heated, which is causing your connections to get loose while printing. Overtime the hole assembly gets loose and leaky.

It may sound false that expanding or material makes the connection loose, but the problem is more complex. Different materials expand differently, so your aluminum cooling block grows different than the bras nozzle. Also the threads expand differently and getting loose. That is why you must screw all components together in heat state at at least 220°C.

Cold assembly may work, but not for long.

I never assemble cold. I understand your point. I use 210 C though.

@roon4660, you’ve had so much trouble with heat creep I’m really beginning to wonder if there is something wrong with your thermistor or control board. Perhaps the heater is staying on far longer than it should, so the heat has a chance to creep up the assembly.

Could also a broken wire, so that the hotend fan is sometimes stopping during print. A broken thermistor would have been detected by the firmware triggering a thermal runaway, unless the option was disabled for some dangerous reason. I always wondered why there isn´t a second thermistor designed to sit in the heat sink, so wiring problems can be detected quite easy. Probably to expensive.

@Geit, you hinted at something I thought about last night and told myself I needed to ask about this morning. That is, @roon4660, you have 2 fans on your Ender 3, one on the front and one the side, right? In fact, I think your hotend is identical to the stock one on my Ender 5.

If this is so, then my question is: when printing, is the fan on the front running the whole time your Ender 3 is printing??

@Geit, re: the thermistor, I was thinking more of an intermittent connection to the thermistor, or a control board problem wherein the board is not limiting the power to the heater the way it should. I agree, it seems unlikely, but still.

My fan is always running. I even bought four more of them so that I had replacements in case these break down, but they work fine. I am just wondering if I should print out an alternative ducting system to try out and see if I get better results. Maybe I will check out some YT alternatives. I know that chep has one and teaching tech has another. I am trying an ordinary tube jammed inside my hot end instead of the capricorn because the capricorn seems to be changing and causing sticking. Maybe I should just change that little piece regularly. The ordinary white tubing doesn’t seem to help.

I would concentrate on keeping the upper part of your hotend cooler. If you can cool down that part of the system, I suspect your problems would go away. The real question is why is it that the normal cooling isn’t keeping that part of your hotend cool? It seems strange. It’s almost as though you need a duct aimed directly at the top part of the hotend.

I agree. That seems to be my problem and it seems to happen to others now that I think of it.

I can’t say as I’ve run into anyone who’s had the issues you have, at least not with the frequency you’ve experienced.

I’m just lucky I guess.

In some cases, I have found that I need to add a spacer to the Bowden coupler to keep the Capricorn tubs my fixed in place. The BondTech extruded is known for this problem, for example.

I’m trying to picture in my mind where, and how, that spacer would be placed… nope, can’t picture it.

Here is an example of one. It keeps the coupler’s teeth from slipping. Ender 3 pressure fitting fix by Redsalamander - Thingiverse


Ohhhh, Locking Rings. Now I get it. Yeah, pretty much every coupler comes with those. I was trying to picture where a spacer would go in addition to the locking ring.