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Anet A8 hotend problems : leaking filament

This article is how to find out whether your Anet A8 hotend has been assembled correctly.

 Common Problems with the Anet A8 hotend

There are three main problems associated with the hotend which anet a8 hotend :leaky nozzlewill be dealt with in this article.

  • Filament leaking from the top of the heat block
  • Filament leaking from the bottom of the heat block
  • Hotend loose when heated.

When you receive your Anet A8 the hotend will probably be assembled, mine was. What you don’t realise is that it is probably assembled wrong – as mine was!

You assemble the unit onto the printer and start printing.

After a short while there appears at the top of the heatblock some molten filament.

If you are unlucky this can increase and drop down onto your printed model and either catch with the nozzle or cause detaching problems when the nozzle knocks your print off.

In the best case where it doesn’t drip you are left with a lot of filament stuck to the top of the heat block, requiring cleaning up.

Or the filament starts oozing from the top of the nozzle and drips onto your model causing problems.

Or after heating up the printer you start printing and notice that the heatblock is spinning around and causing printing problems with your model.

Whichever it is this needs to be rectified.

 What is the hotend made up of?

The Hotend is contructed of a few parts. these include:hotend components

  • The throat
  • The liner
  • The heat block
  • The cartridge heater
  • The thermistor
  • The nozzle

The liner is usually made out of PTFE material, slippery and heat proof. This is the insulation while the filament goes through the extruder.

The PTFE tube is fitted inside the throat, made of stainless steel. It goes right down to the bottom to be butted up against the nozzle. The throat forms the connection between the extruder and the hotend. It also forms the heatbreak to prevent heat from the hotend from backing up the throat causing blockages.

The metal heater block holds all of the parts of the hot end block together.

The Cartridge heater, a 12v 40w heater raises the temperature of the heat block above the melting point of the filament.

The thermistor gives the controller some feedback on the temperature of the heat block. Once close to temperature the heating is cut back so that it doesn’t overshoot. It closes the loop of the cartridge heater into the heatblock to the thermistor, back to the controller.

The nozzle is the melt zone. Once liquid the filament is forced through the opening in the tip of the nozzle. The semi melted filament forms a plug which pushes the molten filament out of the nozzle.

How to disassemble your hotend properly

Once you have used your hotend it will be fill of filament.extruder assembly removed from printer

If you try to disassemble this when it is cold then you stand a good chance of breaking it.

If the nozzle has stuck this can shear off when trying to unscrew it.

Or the throat may snap, again with the filament stuck to it.

So what do you do?

I tend to cut off the filament at the top of the extruder rather than trying to remove it by pulling out.

Switch your printer on and warm it up, it doesn’t have to be at the melting temperature, just above the transition temperature from rigid to flexible – which on PLA occurs at about 50C.

So set the printer to preheat PLA – if PLA is what you are using, and go back to the main screen. Watch the temperature until it rises above 60C and you can then switch the printer off.

To remove the nozzle at this time, use a pair of molegrips ( visegrips) to hold the heatblock- carefully avoiding the heater cartridge and themistor.

With the correct size spanner unscrew the nozzle. This should turn relatively easily now the plastic is warmed.

Place it down on something that can withstand the heat without melting or being damaged. – I put it on the printers bed.

On the Anet A8 the hotend is held in place with the lower bracket of the extruder motor.

If you undo the nut and the allen bolt holding this bracket to thehotend removed frame and the two screw holding the extruder motor you can remove the throat/heatblock/retainer completely.

Now while it is still warm the nut can be tightened up to the mounting block and the heatblock gripped in the molegrips again.

The throat can be removed from the heatblock at this time.

If it proves difficult then remove the mounting block and add throat removedanother nut to the throat.

Tighten the two nuts together, and using a spanner on the nut closest to the heatblock, use the molegrips to remove the heatblock from the throat.

You may need to clean out the threads of the heatblock or replace it if there is damage to the threads.

Check the throat for damage to the threads or to the PTFE liner. If it is blackened it may have been overheated or bits of filament may have overheated – these can break off and cause partial blockages in the nozzle while printing.

As they are only a couple of dollars then replacement would be the

removed nozzle
all the black is overheated filament ready to block the nozzle

best move – keep these in stock as consumables.

Remove any remaining filament and make sure that all of it is cleaned before reassembling.

 Assembling Your 3D Printers Hotend Correctly

To assemble your hotend correctly make sure you have all the pieces available.

Nozzle, throat, heatblock and that’s it. If the heatblock has the hotend partscartridge heater and the thermistor installed make sure you are careful with the wires. You don’t want to reassemble the hotend onto your printer just to have the wires break.

Personally I reassemble the hotend cold and have had no problems, others are not so lucky and perform the last stage hot. This is something you will need to try and see which way works best for you.

Taking the nozzle, screw this into the heatblock by hand until it goes

tight.

Then unscrew it by 1/2 a turn.

Now take the throat and screw that in until it is stoped by the nozzle.

Using the molegrips, hold the heatblock to stop it rotating while using a spanner to tighten the nozzle onto the throat.

Don’t over tighten the nozzle, it need about 1/16th of a turn to take up any slack in the threads and to prevent it leaking from the joint between the nozzle and throat.

After you have tightened this examine the nozzle to see that there is still a small gap between the body of the nozzle and the heat block.

Now the nut to hold the hotend to the extruder can be screwed down the throat, if it was removed.

And the mounting block screwed onto the throat.

The throat end should come to the top of the mounting block or slightly protrude. The wires for the heater and thermistor will orientate themselves to the correct position as they were when you took the assembly off.

Offer the assembly up to the extruder and screw in the allen bolt – do not tighten. Align the mounting block and tighten the nut up to the extruder mount. Tighten the allen bolt.

Place the spring for the extruder in the correct position and holding hotend installeddown te extruder motor screw this back in with the two allen bolts. It is easier to locate the one furthest away from te spring first and using that as a pivot locate the one closest to the spring – then tighten both up.

You now have a reassembled hotend which should not leak.

Note: if your hotend becomes loose when you have heated it then hold the heatblock in molegrips and tighten the nozzle  – make sure it is not tight against the heatblock when fully tightened.

Testing your hotend

Switch on your printer and make sure that it starts up ok.

Locate the hotend temperature menu and start the process.

Go back to the main screen and watch the temperature rise on the hotend.

Make sure it stabilises where you set it.

Straighten the end of your filament and feed it into the extruder. Pressing down on the tension spring will allow you to feed the filament in without turning the motor.

Manually push it through until you see filament coming out of the nozzle.

Stop pushing. and release the tension spring.

Look for signs of leaking, both at the top and bottom of the heatblock.

If there are then hold the heatblock with the molegrips and tighten the nozzle.

You now have a working hotend on your 3d printer which will not leak.

After clearing and reassembling your hotend you will need to go through leveling your bed as the height of the nozzle will not be the same as before.

Other solutions for the Anet A8 hotend

I have heard that people are putting teflon tape around the threads to prevent leakage- if you get the joint tight between the nozzle and the throat then you really don’t need anything else.

And don’t use thread lock on the threads of the throat as you may not be able to disassemble it in the future. If there is still a problem then the joint between the nozzle and the throat is not correct and needs attention.

If you really cannot get it to stop leaking then try to flatten the faces nozzle flattenedof the nozzle and the throat on some wet n dry paper – if you don’t get it really flat it may cause more problems than solving.

The complete new assembly is available relatively cheaply to purchase from Amazon. Don’t forget to check it before fitting as most manufacturers don’t assembly these properly from the factory. Go through the assembly process of loosening the nozzle and tightening the throat down onto the nozzle.

If you find that the teflon tube is blackened at the end where it meets the nozzle, it will be worth checking your temperature settings for the material you are using. too hot and it will start to overheat and stick internally leading to more blockages.

I tend to polish the inside of my nozzle before the first fitting – does this do anything? well I have very few problems with partial blockages so every little helps, and it only takes a few minutes.

Thanks for reading and please fill in the survey whether you tightened your anet a8 hotend hot or cold.

Do you assemble you hotend hot or cold?

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Phil

3d print Journal 10-01-18 : Slicer Vase Mode

Happy new year to you all.Anet A8 upgrades : Anet A8 3d printer

Prior to the Christmas break I was printing with my Anet A8 3d printer.

I had the slicer vase mode set– if you haven’t tried it you must.

Vase mode produces, in some slicers, a continuous spiral – no steps in layers and only one shell thick no infill.

Great for vases!

But people have found that you can print other items, which follow the rules – continuous circuit on each level.

So a mathematical christmas tree and other objects have appeared.

The first slicer I tried with vase mode was KISSlicer.kisslicer logo

You have a lot more control over most things with this slicer and it can be very confusing to start with – it is really frustrating that most of these slicers call the same thing by a different name – just trying to be clever I think but to the end user it is very confusing.

Anyway, I had gone through a certain number of calibrations with KISSlicer and thought I was getting somewhere.

They have model which does not slow your printer down as a calibration piece. Download it here.kisslicer vase mode

So I was getting on with the vase mode ( found by sliding the infill slider to the right in the style tab) and not really being happy with the fact tat it would print like a normal print – with the z axis going up a full level each layer, but with no experience in vase mode how do you know different.

I started printing out the Christmas trees, and found a few problems -like minimum layer time – the printer would, at the top of the tree, raise the print head and wait then resume. The top would then not print properly.

Another reason to look at the sliced file before printing, so I did next time and thought I had cracked it – it was ok until about 1cm from the top where it did the same again, even with the min time per layer set to 0.

so enough of this I changed slicers, I went back to the one I think most people have used Cura.cura logo

Reading through some of the older posts on forums I came across the fact that in cura vase mode was called ‘spiralize the outer contour’ – vase mode is shorter and more descriptive!

Activate it by going into expert settings and click the selection.

old cura vase mode

So I tried a print in this and wow – I sat there for a fair few rotations of the christmas tree, watching the z axis continuously turning ever so slowly the print nozzle never stopping and the filament continuoulsy being fed.

What a joy!

The print – well there was no seam to start with, it was as people had described vase mode – a very thin single layer structure.

And it printed to the very tip with no problems!

I like the idea of KISSlicer and will go back to it in the future, but at the moment I am back with Cura, version 15.04.6 at least.

With the success of this I looked on thingiverse and downloaded a few more vase patterns – I can recommend the vases by  Ferjerez Mathematical creations which if you have scad you can play with.

Some of the vases and bowls absolutely stunning – thank you Ferjerez.

Printing some of the vases I noticed that in the overhangs there were gaps, looking for the answer online I read that this was due to poor machine setup, hmm what had I done wrong?

I had printed a few more things in ‘normal’ mode and came back to this.

Setting the slicer up and saving the gcode I printed another vase and waited.

This time the walls were thicker and it had all worked, even the overhangs had printed properly.blue vase worked ok

Looking at the settings in Cura I had left the wall thickness at 0.8, printed with a 0.4mm nozzle. I didn’t think this was possible, but it did it, over extrusion maybe? But I don’t care it worked.

So I went ahead and printed a bowl from the same pack and again it came out with a thicker wall thickness sslicer vase mode green bowland was able to hold its shape well.

I downloaded the later version of Cura – 3.0.2 at that time and had sliced the same model, I need to sort out the start gcode so it acts the same as the old version and not drag the nozzle across the bed.find it here in later versions

I hadn’t really explored it with this program and updated to version 3.1.0, it loads so slooowly on my PC.

I downloaded another ‘ test your printer’ file by majda107 and h

ad sliced that in the latest Cura, saved it – had a quick look at the layers and copied it across to my sd card.

On printing it I thought something was wrong with my printer – the first layer would not stick and the further the machine got into the print the worse it was.

Using a screwdriver I was constantly adjusting the height of the bed – flashbacks of the old days when my Z axis endstop was loose – nope it still wouldn’t stick.

I happened to glance up at the display and saw the Z height at 0.8mm and thought – that’s strange it should be on the first layer, how come.

Then it dawned on me, my hand slid slowly around to the reset switch on the main board and pressed it.

The print head was slid across to the left and the mess on the bed was cleaned up.

Back to the PC to slice it again – this time untick the ‘spiralize the outer contour’ and slice it again.

Yes I did laugh and wonder at the software engineer who could have added something to the display to say that you are in a ‘special’ mode rather than standard mode. But no they leave you in the dark with most of this. And people wonder why 3d printing does not take off with the masses!!

yes I did check the layer mode more carefully this time and yes it did print more than just an outer shell. I do wonder what it really would have printed if I had left it and the layers had stuck together- would It be a ghost outline of the model which it was going to print?

So if you take nothing else from this – make sure you check that you are not going to print in vase mode when you expect something else!

And increase the wall thickness of vase mode to make your models a lot thicker and stronger.

I did notice when playing around with the later Cura 3.x.x you will need to exit the program and restart it to get the model to slice correctly.

Good luck with your printing. so go and have fun with your slicer vase mode.

Thanks for reading

Phil

Anet A8 bearing replacement- SB1

Service Bulletin 1 (SB1)Anet A8 upgrades : Anet A8 3d printer

This service bulletin details how to check and perform Anet A8 bearing replacement on the X and Y axis.

What are the symptoms which require Anet A8 bearing replacement

After you have bought your 3d printer and used it a fair bit you may notice a few strange noises.

Where the print head used to glide across the printer, you notice a knocking noise as it changes direction.

When the bed changes direction there is a visible jump.

Well the main cause for this could be wear on the linear bearings. Continue reading Anet A8 bearing replacement- SB1

5 Mods for the Anet A8 3d Printer

The Anet A8 is a cost effective introductory printer into the 3d 5 mods for the anet a8 : Anet A8 3d printerprinting world.

As a build it yourself model, it is up to you how you modify it.

The standard build is good and will teach you a lot about 3d printing.

But it can be improved on easily and cheaply. Continue reading 5 Mods for the Anet A8 3d Printer

Cooling nozzles for 3d Printers – What do you need?

Testing the cooling nozzles on an anet a8cooling nozzles in situ

Are you happy with your prints from your 3d printer? Could your cooling nozzles on your 3d printer be part of the problem?

Check out what it is for and how it does what it does. Continue reading Cooling nozzles for 3d Printers – What do you need?

3D print Nozzle secrets

All about a 3d print nozzle

3d print nozzle : main

Continue reading 3D print Nozzle secrets

Where to place your 3d printer for the best results

person shrugging

So you have bought yourself a 3d printer- excellent, now- where to place your 3d printer for the best results.

With the helpful hints in this post you can be sure that if you follow them you will get the best results from your 3d printer. Continue reading Where to place your 3d printer for the best results

Build Your Own 3d Printer Kit: Renren3d LE (A Delta Printer) Part 4

Build your own 3d printer kit – part 4 – programming

So you want to build your own 3d printer kit, so did I – I bought the renren3d le printerRenren3d LE kit.

If you have been following along you will have a built a printer and be waiting for it to work.

Just as a recap.

This series of blogs is my build of the Renren3d LE printer

The series so far consists of

Part 1 – initial setup

Part 2  – frame build

Part 3  – fitting the electronics

And this is part 4 – the programming of the unit Continue reading Build Your Own 3d Printer Kit: Renren3d LE (A Delta Printer) Part 4

3d printer problems: hardware error: build platform heating up when printer first switched on

A little while ago a friend had a problem of the build platform bed heating no powerheating up when printer first switched on. He asked why?

Make sure you are not seeing residual heat from the last print. Leave the printer on for a couple of minutes and watch for a temperature rise on the heated bed before going through this fault diagnosis.

If you see the bed temperature rise above 50C on it’s own ten switch off and follow this fault diagnosis. Continue reading 3d printer problems: hardware error: build platform heating up when printer first switched on