Help Please

[AndyB]

Hi Guys,

This is my first post on this forum and I hope someone here can give me some help to solve a problem with my printer.

I have had an Ender 3 for about a year now and have been fairly sucessful in printing on it. I had the usual problems of warped bed etc and have carried out all the usual mods such as belt tensioners, dual Z axis drive, updated bed springs, updated to Creality silent board, BLTouch, polycarbonate wheels on all rails, side mounted spool holder, dual drive metal extruder and an endoscope camera to view the printing. I also fitted a mirror tile to the bed.

Recently, within the last week, I started getting a problem. When I print something round the surface is very blobby all over. Not as bad if I print a cube. When watching the print via the endoscope I can see the molten filament is coming out the nozzle in spurts.

Initially I thought it was the roll of filament. I've always used "Eryone" filament from Amazon, but had to get a different brand recently as they were out. I swapped back to one I've used before but the problem remains.

Things I have done:

Replaced the nozzle.
Replaced the capricorn bowden tube.
Checked the level of the bed.
Set slicer (Cura) back to default 0.2mm profile.

My Cura is version 4.6.1 and I'm printing in PLA.

Settings are:

Standard 0.2mm profile.
Infill is 10%
Nozzle temp is 200 degrees.
Bed temp is 50 degrees.
Flow is 100%.
Print speed is 50 mm/s.
Initial speed is 20 mm/s.
Retraction distance is 5 mm.
Retraction speed is 45 mm/s.
Coming is set to "not in skin".
Cooling is 100% and set to start from 4th layer.
Max resolution is 0.05mm.
Max travel resolution is 0.05mm.
Max deviation is 0.025 mm.


Any advice/suggestions would be very much appreciated.

Cheers,

Andy

[Butt_blaster]

Hmm, maybe check the eccentric nut on your x carriage, if it's not tight enough you'll see that kind of spurting caused by the nozzle actually being pushed upwards a little as the goo is forced down. It's believable that when you replaced the wheels the problem never really revealed itself, or maybe it turned over time because the wheel it's on isn't tight enough. (Make sure all the wheels are quite tight but not neanderthal tight.) Try to watch the carriage very closely to see if there are any very slight up and down motions. Aside from that maybe babystep up during the print and reduce flow.

[curious aardvark]

Congratulations Andy :-)

You not only produced a concise and informative post with all relevant information - so rare it's a thing of true beauty.

But inadvertently pointed out why ender 3's are not neccessarily a good buy.
Just out of curiosity - have you ever added up all the extra money you've spent on the machine ?
It would be interesting to add that to the original cost and then see what machines you could have bought for the combined cost.

I am genuinely impressed with your post - if only all our members were so forthcoming with information.
Butt-blaster(really ? lol) sounds like he knows what he's talking about :-)

[AndyB]

Hi Guys,

Thanks for taking the time to reply.

Butt_blaster: Strangely, I have a ding on the Y axis rail and have just purchased a replacement for that. Wheels tension looks fine and I don't see any movement of the bed when printing.

Curious Aardvark: many thanks for the compliment. I'm an Ex-aircraft engineer and have always been in the habit of giving as much information as possible. If nothing else it allows people trying to help to rule out a lot and therefore not waste their time. I retired a year and a half ago and the guys at work had a collection for me. I used £100 of that to buy the Ender 3. It was 2nd hand but had not been assembled and was on eBay. To be honest I haven't costed all the upgrades (maybe I just don't want to know how much I've spent on it.....).

Thanks once again,

Andy

[Butt_blaster]

Sorry, I meant the x carriage. I had a problem with the blobs coming out that I traced to the x carriage bouncing up and down because I'd installed a direct drive upgrade for my printer and not tightened those wheels. In the same vein, did you recalibrate esteps/mm on your e & z when you upgraded? If you decide to re calibrate z, try to measure from the frame on the left, if you measure from the bed, the bed has springs that will go up and down to throw you off.

I've spent something like $150 on Ender 3 upgrades, it still doesn't work. Would recommend against it if you actually want to 3d print. It's a good "beginner" printer in the sense that if you want to give 3d printing a shot to see if you can do it and it's useful to you, you can buy one and print little cats and cups and then when the novelty has worn off you can toss it in the corner of the garage and forget about it without feeling too guilty about having bought a $700 towel rack. It just starts to fail hard as you move to printing anything other than pla, or anything requiring lots of retraction. The silver lining though is that I have gotten kind of good at trouble shooting 3d printer problems, much better than I ever wanted, simply because the ender 3 will encounter just about every single problem a printer can have and then create some new ones. Speaking of which, you'll have to excuse me, I have to spend an entire Saturday poking at my stepper motors with oscilloscope probes because my wonderful ender 3 has developed a horrible stutter that only surfaces during z leveling, which as far as I can tell has never been documented before.

[Minnie]

The protrusions on the top layer of the part can be either open or closed. In fact, this is due to the sagging of the plastic, which does not have time to cool when printed in air without supports. Considering that there can be several such layers and all of them are of poor quality, we get this defect.How to fight:Provide Cooling - Your plastic should cool well on the top layer. According to the recommendations, at this stage the cooling should go to the maximum.Provide Adequate Layer and Wall Thickness - In addition to sufficient cooling, you must have the required number of layers. Again, according to the recommendations, your wall should consist of at least 6 layers of your thickness. Thus, when printing with a layer of 0.1 mm, you want your wall to be at least 0.6 mm. But remember - base layers that are too thin won't work either - they just won't hold themselves and other layers.Try to change the occupancy - some slicers change the occupancy configuration at a certain percentage of the occupancy, that is, the difference may even be between 24% and 25%. In addition, with higher occupancy, the distance that is printed in the air is less, which can also remove this defect.

[AndyB]

Butt_blaster: That would make sense. Yes, I did check the calibration of e-steps (spot-on) and Z Axis. As I've spent the money for the upgrades over a long period of time it's doesn't feel like a lot (probably is).
I've produced a lot of stuff on the ender. I made a playhouse for the grandchildren and used it for a unicorn wind vane, nut covers, name plate etc. I've also printed a lot of bits and pieces for my wife for her greenhouse. I just finished printing and painting the collective lever, handle and switch panel for my simulator. It has been well used for what was a very cheap machine.

Up until now I've been happy enough with the surface finish.

Minnie: The blobs are on the sides and are worse on circles than on straight walls. I did have the problem you described a while ago, but increased the number of top/bottom layers and that fixed it. I have 100% cooling from layer 4 set in Cura.

I have just finished making the new Y axis rail and fitted it. When I went to put the carriage back on I noticed that the bearings on the wheels were "rough". There are also grooves worn around the tyres where they fit in to the extrusion. I've ordered another set of polycarbonate wheels to try and see if that fixes the problem. If the bed is not smooth that could explain the blobbing. They needed replaced anyway.

Cheers,

Andy

[Roberts_Clif]

When replacing your PTFE tubing if it was melted on the bottom it could have caused a clog in the hot-end.
This may require you to rebuild the hot-end cleaning and/or replacing all the bad parts.

[AndyB]

Hi Guys,

Finally got to the bottom of this problem. I did the following but it didn't help.

Fitted the small piece of capricorn tube and washer in to the hotend.
Replaced the wheels on the Y axis as they felt a bit rough.
Replaced the extrusion that the Y carriage runs on (it had a few dings in it).
Re-leveled the bed and did an e-step check.

It was when I was leveling the bed that I noticed the problem.

I have fitted a dual Z axis drive I made up myself which has a GT2 toothed belt drive from the original threaded rod to the second one on the other side. I noticed that the gap on the right side of the bed/nozzle was sometimes a bit bigger then the left. Because they are connected with the belt/pulleys they should always be the same. When I checked further I noticed that the top bearing support bracket on the left side was broken. This was allowing the threaded shaft to move. This was producing a temporary change to the horizontal level of the X axis extrusion which in turn led to the "blobs" on the print.
I assume it was worse on the round prints because the head is moving about more.

I clamped the bracket back in place and re-leveled the bed - spot on !!!

Tried a print and it's back to normal.

I'll now print a replacement and fit it.

Thanks for all the advice and help.

Cheers,

Andy

[AndyB]

Hi Again,

It seems I spoke too soon.

I printed a replacement z axis shaft bearing brace and fitted it.
Then re-leveled the X axis with respect to the top of the frame.
Then leveled the bed to the x axis extrusion.
Set the Z offset, and cleaned the bed.
The test prints I did were fine, but when i tried something with a tight curve I had the blobs again. So frustrating !!!

I did a lot of online reading and finally found a post on another 3d printing site saying that Octoprint could cause this type of issue. Seems the Raspberry Pi or the 8 bit motherboard can't keep up with all the calculations required to produce a curve by making very short lines.

So - dug out the micro SD card that came with the printer and copied the model on to it. Put that in the printer and crossed all fingers and toes (very painful, but worthwhile).

It was PERFECT !!!! I tried another couple of circular prints and they were spot on as well.

I was already thinking of upgrading to a 32 bit motherboard so I've ordered an SKR Mini E3 one. For £36 you can't go wrong can you ????????????

I'll let you all know how it goes after fitting it. For just now I'll be transferring everything on the SD card.

Cheers,

Andy