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fiteeket

Mankati XT bowden tube replacement & cleaning tips needed

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fiteeket    0

Hi,

First of all - sorry for my english. I'm not a native speaker.

I've had the Mankati XT printer for quite a long time now. I haven't used it for about a year now as I got very frustrated with its extrusion problems.

I got some really fantastic results with the printer before the extrusion problems started. I used to print big objects (almost 30cm tall) in 80 microns and they turned out just amazing. Of course the time the prints took were long but I always thought that I didn't want to sacrifice any quality so I printed in 80 microns. First I thought that the Mankati XT had to be one of the best printers out there as I was blown away with the supersmooth and big prints.

Then came the underextrusion problems. The prints started to fail almost every time by underextrusion and/or clogging. I tried basically everything to fix this issue with no results. I tried a lot of different print settings and cleaned all the åarts of the printer that I could. For a long time I thought the problem was the nozzle but obviously it wasn't as I replaced it and gave it an acetone bath. Nothing fixed this issue and eventually I frustrated so much that I quit 3D printing.

Once a while I have returned to read some of the topics here and I have noticed that a lot of people struggle with the same problem. Apparently the cause of the problem is the bowden tube that gets clogged near the hot end. Now I decided to write my first post here as I really want to fix this issue and get my printer running again.

 

How do you clean the clogged up tube without damaging the tube itself? What kind of tool do you use for this operation and where can you get a right sized tool like this? How often do you have to clear the tube to avoid the problem?

 

Would you suggest to replace the clogged tube to resolve this issue? How do you do this and do you have to dismantle the whole hotend for this? Does this really fix the issue or will the new hotend end up clogged as well?

 

Some people have replaced the Mankati XT extruders with Bondtech extruders with good results. I wonder if these strong extruders just push the filament through the clogged part and by this solve the problem. Do you know if this is the case or is it related to a separate issue?

 

Thank you in Advance,

fiteeket

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mvm    12

Hi Fiteeket,

Long post but with a familiar problem :)

I have both a Mankati XT (my first 3D Printer) as well as the XT Plus (second printer).  I basically used them every day for print.
The XT has been used for about 6700 hours now, the XT Plus for 3380 hours. Both are busy printing as we speak.

I have had problems with both printers because of clogged nozzles.
With the XT, when the printer is having issues with extrusion, it is either the nozzle being blockedd OR the last part of the Bowden tube that extends into the nozzle has some filament residue stacking up inside.

If you have printed for a long time and you remove the nozzle, you will notice that the end of the Bowden tube has become brown and or has even deformed.

The first thing you can do is use a 2.5 or 3mm drill bit and simply drill out any remaining and stuck filament in the tube. I sometimes push a 3mm iron wire through the whole Bowden to push out any remaing stuff. 
This will work for some time but after having done this several times, you will have damaged the inside of the tube and the problems will reappear.

Second thing you can do is to remove the PEEK block, loosen the tube and push it through 1-2 cm and cut if off again at a point where it is nice and clean again.
Make sure you cut it off straight because otherwise you will be oozing filament out of strange places.
This is a bit of work and you will have to fiddle a bit for the first time. Just make sure you do not bend the guide rods of course because that would ruin your printer.

You can also buy a new Bowden tube and replace the whole tube. I have done this on March 26th this year and the printer has been running another 1150 hours since.

To be honest, I do get failed prints sometimes because the nozzle can still get clogged. Usually this happens after switching different types of filament

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fiteeket    0

Hi mvm,

Thank you for your helpful reply!

Was it difficult to replace the bowden tube? Did you find any instructions on how to do this?

Do you have experience with Bondtech extruders and do you experience any extrusion problems besides the ones that the clogged nozzle might cause?

How would you compare the XT Plus to the XT? Would it make a big difference to replace the hotend to the XT Plus one?

I hear that you use your printer on a day to day basis. What do you think is the most time consuming part to maintain it's operation and how often do you have to level the bed?

 

Sorry for the million questions :)

 

Br,

fiteeket

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mvm    12

Hi Fiteeket,

No problem.

Yes, replacing the tube on the XT is a bit of a fuss because the clips by which it is secured to the (red) guide block are a bit difficult to remove. Or perhaps I simply did it the wronig way. Also, the tube swells a bit after long use and will be very tight in the PEEK, so that is hard to remove.

The XT Plus is much more simple, because you can simply unscrew the Bowden tube from the guide block. I often do this if the nozzle gets clogged, just to push  a bit of filament through to see if I can clear it that way (often helps) or to just put a few drops of sunflower oil in it. The oil seems to reduce the tendency to clog.

In total, my XT has had twice the printing hours of the XT Plus. That said, on the XT I never got printing with ABS correct so I simply don't use ABS on the XT. With the XT Plus, printing ABS actually works very well. I am not sure why this is, but on the XT, my ABS layers never seem to be as strong as they should be.

I really don't level the bed very much. I use 3D Lac spray to simply put a thin cover on the glass bed and that sticks very well. Except for Nylon that is, but I don't used that much any more. 

On the XT Plus, I need to replace the cooling fan again because on of the wires got lose. I really want to design a new fan holder for the print cooling fan. The original model always gets damaged after a while. At the moment it works. I have a E3D V6 Hotend with all the works, but I haven't had the time to install it yet.

Actually, at the moment, I don't get that many clogged nozzles any more.

I have no experience with the Bondtech extruders. About a year ago, I was really thinking about getting one (on the XT), but after getting my Bowden tube problem solved, I don't seem to need it anymore. 

My basic procedure for a print is simple.

1) Heat the printer and bed to the right temperature
2) While doing that, I wipe the printbed with a slightly damp cloth and then spray a bit of 3D Lac on it in the area where I am going to print.
3) Extrude about 15-30 mm of filament from the nozzle after heating it up. The way the filament will flow usually tells me already if I have a clogging problem. Also, I usually need to do this after switching filament type and/or color to get the last remains out of the nozzle
4) Start the print.
5) Watch the way the first layer is laid down. If it doesn't go right, I immediately stop the print, lower the bed, clean it and start again.

 

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