Repairing 3d Printer Hot-End and tuning up your Anet.
I ran into some trouble repairing an Anet E12 3d printer recently because a lot of the parts now available are not what was used for the hot end I have. I suspect others will come across the same problems with the same model and other printers by other manufacturers and so I’ll explain the problems I had and how best others should go about fixing them.
The trouble started with the heat-sink which was of the older flat kind instead of the newer cylindrical kind. The grub screw which holds the throat in place stripped out and so I decided to replace the heat-sink thinking that would be the easiest way to repair the printer, but I was quite wrong. I had also considered drilling and re-tapping the grub-screw hole for a screw that was slightly bigger, but I thought against it since I didn’t have any taps of that size and there wasn’t much space left to do that on the heat-sink. I considered flipping the heat-sink over and tapping the reverse side, but again I didn’t have a tap of the required size and I figured replacing the heat-sink altogether would be the most direct way to repair the problem.
However that choice became a very expensive error for when I received the new heat-sinks I had ordered I found that the hole for the throat at the bottom of the heat-sink was too large to hold the throats I had.
Here are the new heatsinks. They did not include any grub screws and they have 7 mm holes in the bottom for the heat-breaks/throats and 6mm holes for the connector in the top. https://www.amazon.com/gp/product/B07PHDMWQ4/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1
Apparently the old style throats are six millimeter along their whole length and the new ones are six at the end which screws into the heat-block but enlarge to seven millimeters along the rest of the shaft. So I went ahead and ordered new throats, but I was a little concerned as they appeared to be shorter than the original ones and once I tried them this proved to be a problem.
Here are the new 7mm shaft, 6mm bottom, heat-breaks and they come with tips/nozzles, heat-blocks, and insulating silicon socks/sleeves: https://www.amazon.com/gp/product/B07K9HFFYC/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1
The new throats are called “heat-breaks” and they are designed especially for cylindrical heat-sinks which are common on the hot-ends made today like we see on the Ender v6 All Metal Hot-Ends.
Here’s a link to Ender v6 type hot end, but a cheaper branded Gulfcoast Robotics. Notice how the connector doesn’t look like it has enough insider diameter for the bowden tube to go all the way through? That’s a PROBLEM we’ll get to. It’s easily fixed.https://www.amazon.com/Gulfcoast-Robotics-Hotend-Extruder-Printer/dp/B07B4FL12R/ref=sr_1_4?keywords=ender+v6&qid=1567106066&s=industrial&sr=1-4
They make longer heat-breaks with no threaded 7mm tops apparently too though. I think these would be better than the threaded kind if your heatsink doesn’t have a threaded connection or if you have one of the bowden connectors that don’t allow the bowden tube to pass all the way down into the heat-sink to meet the heat-break. I ordered some and I am almost certain this will solve the problem but I haven’t tried them. They look like they’ll work flawlessly. https://www.amazon.com/gp/product/B07MVVD99L/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
Not only is there a problem with some of the heatbreaks not allowing the passage of the bowden tube down them, but also in the older style setup the bowden tube wouldn’t go down into the heat-sink very far. It would either be stopped by a smaller diameter shelf within the bowden tube connector (the connector is screwed into the top the heat-sink and is what holds the bowden tube in place) or it would be stopped when it hit the older style throats which were long.
So in either case the bowden tube wouldn’t go very far into the heat-sink. If the filament passed any distance while not being in a bowden tube or throat it was near the top of the heat-sink where there isn’t much heat so as long as the heat-sink and fan was working correctly there wasn’t usually a feeding problem, but in some cases when heat would creep up the system you might run into trouble. In those cases you would be able to feed the filament in, but once the filament retracted a bit because it was soft it wouldn’t feed back in and would curl near the top of the system and cause a blockage.
That will surely happen if you use the newer system with the shorter throat/heat-break if the bowden connector you have is of an older kind with a shelf inside which does not allow the bowden tube to pass all the way down to meet the heat-break. This is what happened in my case. So I had to replace the bowden connector also.
I used these. The white metal ones allow the bowden tube to go all the way through. Yay! And they included three bowden tubes. Yay! And brass threaded connectors that you can thread into the tubes if I want to use the bowden tubes for a watering system someday. Yay? https://www.amazon.com/gp/product/B07NXQT75Y/ref=ppx_yo_dt_b_asin_title_o03_s01?ie=UTF8&psc=1
Now with the new heat-sinks, the new bowden connector, a the new heat- breaks, I suspectedthe system would work correctly but I didn’t install it for a while since I repaired my old system in the mean time. I found out the new system STILL DOESN’T work. I’ll explain why but first I noticed a few other issues which you may encounter:
The opening of the heat-breaks which receive the bowden tubes are a bit oversized in some people’s which means the bowden tube can too easily be retracted. This isn’t much a problem since the bowden connector is what holds it in place, but some people have complained that their connector didn’t hold the bowden tube tightly or else actually pulled it out a bit when the button which opens it up to allow the bowden tube to pass through it was un-depressed.
Mine are very tight, but if yours are loose perhaps pressing the tube in hard while un-depressing the connector may solve the problem or replacing the connector may fix this, but I suspect at least some people like me didn’t at first notice that their bowden connectors had a shelf in them so that the bowden tube can’t go all the way down inside the heat-sink preventing it from being inserted into the end of heat-break.
Either way if the problem is that the bowden tube is retracting a bit leaving a gap between it and the heat-break the same blockage will occur as I described, but near the bottom of the heat-sink instead of the top.
By inserting something like a very dull pencil into the end of the bowden tube after it has been allowed to pass through the bowden connector and twisting the pencil using the heat of the friction to flare out the end of the tube so that it fits more tightly inside the end of the heat-break may help.
If all else fails a 3d printed part may work for you. A man designed a collet with a tightening nut to replace the bowden connector which should hold the bowden tube in place extremely well, but it should be printed from higher temperature plastic like PETG or ABS so that it does not soften in cases of heat-creep. I’ve provided the link to the invention here.
I printed one and it looks like it would work well, but I’ve replaced my connector already with a new one that has a straight inside and it holds the tube very well so I suspect that the new system will work now.
I also noticed the new heat blocks are smaller than the ones I had so that my long heater sticks out a bit from the end of the new heat-block I bought. I don’t like this as that is wasted heat and having a protrusion of the heat-source from the heat-block increases the risk of a fire and injury. Others use it that way and don’t have a problem with it, but I don’t like it. Eventually I’ll replace the heater as well with the shorter kind since the smaller blocks seem to be standard now.
Now here’s the actual problem: The new style heatbreaks are simply too short. They are so short that upon the first retraction the filament develops a bulge where the heatbreak and bowden tube meet. Even if the bowden tube is tightly held in place this occurs. The reason is that the bowden tube is flexible so bends just a bit regardless when backward pressure is applied. The only solution is a longer heatbreak. It should be as long as possible. If you still have an old heatsink just use the old style throats as they work perfectly. If you have a volcano type tip you also should be fine as those have a single piece for the throat and tip. But if you have the new short heat breaks you might be able to get away with using them IF you insert them fully in the heatsink and you have a lot of cooling from the fans directed at the heatsink. Having a sock on the hotend will help, but it won’t stop the problem by itself. Slowing down the retraction speed and distance can also help, but honestly not much. The ideal solution would be to just get an old style heatsink with those old 6mm holes if you can find any and old style 6mm throats. That’s what I’m using now with the new style block with a sock on the block and it’s working great. I tried the new style heatbreaks with the new style heatsink and it just didn’t work no matter what I tried. Like I wrote if you have a lot of cooling on the heatsink it might, and if you use thermal paste you’ll get much better cooling, but honestly I don’t think it’s worth it to try to make the short heatbreaks which don’t allow the bowden tube to pass all the way through them to work. The old system of 6mm throats worked fine and I wish somebody still made the old style 6mm heatsinks. But the kind of heatbreaks 7mm heatbreaks that allow the bowden tube to pass all the way through them https://www.amazon.com/gp/product/B07MVVD99L should work fine as long as the bowden tube is tightly secured.
So in the end I fixed my heatsink by simply forcing a slightly larger screw into the stripped screw hole. I used the kind of screw used for computer cases. It was tight, but not too tight and it cut new threads that worked. It’s actually better than the grub screw. The first two screws I tried weren’t quite large enough and didn’t hold, but the third did and so I was able to reassemble my old system and it worked quite well. Apparently the stripped grub-screw wasn’t holding the throat very well before and that was making it very hard to tram the bed to what had become a shaky hot end for a number of reasons.
Now another problem I was having is that the side fan which cools the parts down had a broken shroud. They used a cheap 3d printed part that was made with a layer height too high so it broke at the layer just below where the screw hole was which has the most stress. Very predictable problem by anybody who has designed 3d parts so it’s hard to understand why they’d do that, but I had to print a new shroud and I’m trying a few designs. The one I currently tried doesn’t have enough clearance for the heat-block and sits too low on the thing I’m printing and will scrape it a bit so I’m going to try a few designs until I find the one I can recommend or I’ll make one myself. But that’s not the worst part.
The problem is that side fan stopped working. It’s a 40mm x 40mm x 10mm thick downward blowing fan 12 volt. So I ordered a new one. They come in a set of two so I have a backup now so that’s cool. https://www.amazon.com/gp/product/B07RNZF97F/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
After I pulled the old fan I noticed that what had happened is that the solder point for one of the wires had broken. I figure just from taking the unit apart a couple of times the wire gets pulled and eventually the connection breaks. I could have resoldered it and seen if that would have fixed it, but I didn’t like how easily it broke so I opted for improving the machine.
So I went ahead and ripped the other wire off at the other solder point and stripped back the original wires a bit. There wasn’t a lot of wire left since they kept their wires short when doing the assembly but there was enough to work with if I was careful.
The wires are so thin my strippers didn’t work well and I had to be careful.
I considered attaching a connector and had one coming since I ordered a different fan for another thing which I’ll get to, but I decided not to wait for my order to come in and I just cut off the connector from the new fan and I twisted and soldered the connections.
Before I did that I placed heat shrink on both wires and then on each set of wires individually to tie them together for good cable management and to protect the wires from getting pinched when reassembling the hot end. I soldered them together and then I used a heat gun to shrink the heat shrink. It’s great now. I doubt the connection will break again.
I used this heat shrink (a great kit): https://www.amazon.com/gp/product/B072PCQ2LW/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
I noticed though the fan doesn’t spin unless you set it to at least 20% or give it a little kick start by spinning it with your fingers. I guess it needs a good voltage to get going.
One wire is black with a bit of red and the other is just red. The darker wire is the negative end and the red is the positive: Not that it matters. I just put the same colored wires back together, red to red, black to black, and it was fixed.
One note about soldering: I first used a butane soldering gun which I have and which I prefer, but that ran out of butane so I grabbed my old plug-in iron which I hate using since the whole thing gets hot, but it works reliably. It’s just that it takes forever to cool down. And that leads me to a VERY important safety tip:
When soldering you should have a fan going not just to remove the fumes, but also to cool down your iron after you are down with EACH WIRE if you haven’t prepared the wires correctly so that you can both wires at the same time.
Do NOT lay down the iron to prepare the next wire for soldering. Prepare both ahead of time and never under any circumstances try to do anything other than solder when the soldering iron is hot. That’s critical.
Never mess with the wires while the iron is hot and never EVER lay down a soldering iron. Even if your table is magically fire proof AND IT IS NOT the soldering iron WILL roll off your table or be pulled off your table by something pulling on the plug or be knocked off the table onto your floor by you or someone else and it WILL catch your house on fire. And make certain that you also have a cup of water and a fire extinguisher at arms length just in case that happens!
If your other wire is not prepared properly for some reason do one wire only then shut off and unplug your iron and HOLD IT in front of the fan for about ten minutes checking the temperature by touching first the lower part of the shaft and if that’s still warm AT ALL the tip is still blistering hot. Once you feel the shaft is cool check higher and higher. If at any time you feel warmth the thing is not cool. The tip is still blistering hot. Do not lay it down. Do not do anything except cool the iron with the fan. Keep it in front of the fan!
When finally the tip itself is perfectly room temperature you can lay it down and get things ready to do the second wire.
Obviously if you prepare both wires correctly you may not have to cool the iron down after doing the first one but some things happen; like maybe the ends come loose from the second set of wires while you are soldering the first. Stuff happens.
But as long as you don’t try to redo those wires while the iron is hot in your hands and as long as you don’t lay it down until it is entirely at room temperature you’ll be safe.
I recommend using solder with rosin in it. It’s worth the extra cost. Soldering flux and soldering pens are very useful especially when you need solder to move around something or uphill, but in a hurry the rosin core stuff works really well.
Another problem with my Anet I noticed is that one of the fans inside the control box is making a lot of noise. It’s the same size as the other at 40 x 40 x 10 mm, but of a regular fan type instead of a blower. I ordered a new one, a rather expensive one, but the brand has a reputation for being super quiet and it includes special connectors that I want to use.
The fan inside the controller box that is causing problems is not the one near the vent and not the one in the power supply. It’s the one near the front of the system that just helps circulate air throughout. It’s wired directly to the power supply so it shouldn’t be hard to replace, but I’ll be using the connector so I can replace the fan more easily in the future if it ever goes out. This is the one I ordered. https://www.amazon.com/gp/product/B009NQLT0M/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I did notice on the old fan that removing the Anet brand sticker helped the center spin more freely and that cut down on the noise a little, but I’m still going to replace it. I don’t want it to go out when I don’t have time to replace it.
The anet uses round wheels and the one near the front of the print head is loose causing some wobbling so I at first tried replacing them with these wheels but the new wheels were too large in diameter and made of a hard plastic instead of rubber, but it doesn’t matter as the solution was something else as I’ll cover in the next paragraph. https://www.amazon.com/gp/product/B07KXPD6XZ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
The wobbly print carriage/print head is supposed to be easy to fix by loosening the wheel underneath, lifting it a bit and tightening it again. The hole in the mounting plate is oblong allowing you to do this. But it’s hard to adjust. You need three hands to do it well or you have to put something under the carriage to lift it a bit while doing it, but worse there is a serious design flaw on the Anet E12 as it is assembled from the factory. The nylon plastic spacer for the two wheels above are simple cylindrical spacers but the one below is oval shaped on one end and fills the oblong shape in the mounting plate. That sounds fine, but it fits perfectly allowing no play so the wheel on the underside of the print head that you are supposed to be able to lift to tighten the print head so that it doesn’t wobble can’t actually be lifted. Chinese ingenuity I guess. I figure that the spacer was designed for a plate with a longer oblong hole in which case it would work fine, but it fits perfectly so can’t be moved. You could try to fix this by flipping the spacer around so that it doesn’t matter or you could replace the nylon spacer with a regular one like those two above the print head or you could do what I did as a temporary fix and use two metal nuts that make up the same height when stacked together and use them instead of the nylon spacer. I found this worked really well and made it much easier to loosen and tighten the wheel for I could remove the regular disassembly nut and remove the wheel and lift the bolt to the correct height, tighten the first nut I used to replace the spacer a bit leaving a little slack, then the second one I used to replace the spacer and then replace the wheel and disassembly nut and everything went together well. You might have to loosen the wheel above to give yourself a little play to get the wheel back on below, but this is what worked for me. After I got the machine working again I printed some eccentric nuts out of PETG and replaced the temporary metal nuts with one proper PETG plastic eccentric nut which worked perfectly for rotating a eccentric nut, because the hole is offset, tightens the wheel. They sell metal eccentric nuts, but I saved about ten dollars by printing my own part in this case and I have lots of spares and can make more. The .stl file I used was from https://www.thingiverse.com/thing:2630026 and it worked perfectly.
While doing all this I also replaced the shallow headed bolts with deeply recessed hex bolts which are much stronger and won’t strip out. They are slightly shorter so it would be good to get longer ones, but they worked.
I’ll did the same replacing the bolts for the X-belt tension control as one of the heads is stripped out already and really hard to remove.
Also I am replacing the belt tension control with a printed part which will make adjusting the tension much easier. The original model is on thingiverse.com but I’ve already redesigned much of it. The original is here: https://www.thingiverse.com/thing:2482051
Eventually I’ll also replace the tension control for the Y-belt, but that’s less critical to me, but I will use the strengthening device that goes under the heat-bed which was recommended in the video of the part in the paragraph above. I would recommend making that part out of PETG or ABS if you use that since it will get hot.