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When a compiler reach the state, when it can compiles itself, it's called self-hosting.
My Hot-end v3.0 reached that state, and more:-)

I was asking help from Bogdan to correctly set up my machine, that resulted a full weekend debugging on my hot-end...:-) And I continued stress-testing the hot-end with PLA for a full week.

All began with a special PLA filament what I got from Kaipa: namely SuperPLA and OrbiPLA.

Superpla is shinier, more tough to touch, while OrbiPLA is more elastic, looks like, as some kind of rubber.

I also upgraded Rapman firmware from 1.0.8 to 4.0.2s using virtualbox (took me almost a full day, to figuring out that I need official virtualbox for USB support. I used windows like 2 years ago last time.)

First we printed some test triangles. I printed this at 240C without raft:

Printing PLA works on plexi at room temperature just fine, so I taped one of my refuse "squashed frog" down to my quick release bed:

Obviously it is too much for PLA, so I went to 215C:

And I finetuned the triangles wall thickness, to be 0.72mm, ie. between 0.71-0.73mm.

After the triangles were fine, the hot-end tried to print itself:) Ok, only the dummy model of itself, but still it is funny.
Due a mistake I printed the hot-end without fan on, and at too high temperature (215C) and with support enabled.
That means at each layer the hot-end was heated and cooled twice.

But turned out, that this mistake created a perfect testbed. So I started finetuning the hot-end to be able to print this model at the faulty settings. If anyone feels the mood, I attached the .bfb file to the hot-end v3.0 model.

I tried to print with the stock bfb hot-end, but failed miserably. Bogdan pointed out, that maybe my hot-end is faulty, or I builded badly. So anyone is free to print it, but to his own responsibility! Maybe it results a failure like this.


I modified the heatsink, and increased its surface with a dremel tool. It also helps the airflow:

I also noticed, that the power resistors wire itself conduct the heat upwards. So I stopped it by increasing its path, and only the cold part of the wire goes up on the hot-end:

I modified the part on the hot-end and remanufactured it, so everyone will get this improvement.

I also modified the PTFE tube inside, and added on top a small aluminium ring. It really does help.
Now I was able to print it:

The print takes about 6 hours to finish.

The PLA is nasty, it is able to flow out by graviation from the nozzle at high enough temperature:

It is not anymore the inside pressure which creates the ooze..:-(

I also discovered, that more easy to push through the plastic, the more like it will die swell. Which does not really matter on the actual print, as the plastic is always pulled.

Printing PLA with support is really difficult. Especially without fan:)
Also skeinforge seems a bit buggy when it comes to support, I highlighted the part on the picture:

When it printed this part, the extruder motor was not turning, so that is why it looks like the nozzle blocked, but luckily the hot-end performed just fine.

I tried also the cool plugin of the skeinforge, but resulted a complete mess:

Also the raft sticked too well to the object, and also the support was nearly impossible to remove:

So finally, I figured out, that the support should be 155C, while the actual object 205C. It is 50C of difference!

Unfortunately, I ran out of the test PLA filament:(.
So with all the improvements, I could only print the top of the hot-end, so I quickly modified the openscad model:

The result should speak for itself:

It left like one meter of filament, so I played a bit more with the support, and printed discs at 1mm offset, so between each disc only the support were (and a small disc at the middle):

The discs and a pen:

Im pretty happy with the overall result, and Im more confident in my hot-end. It performed really well at the end.

This happened two weeks ago, because unfortunetaly the last week I was out of town because of work, so things didnt advanced by themself:(

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  1. This hot end is progressing nicely :) I really like where you are going :)

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