It has an awesome half circle groove which is a perfect fit for the filament.
I use a normal 608 bearing, so it fits to a Wade style filament pusher exactly, like
the Greg's accessible extruder body (thing:8252). Here is a closeup picture:

Here is how the filament would look like on the bearing:

And also a picture with the hyena:

Oh wait, I can do a better photo, to see from the front (notice the match for frame of reference):

Why is it an awesome thing to have?

• It prevents filament twisting
• It is a guide in itself, Accessible Greg's extruder, needs one I believe, at least for me its needed. (accidents happen:-(

Im collecting ideas here. Im recently trying out many methods to raise funds to manufacture the newest gadget for 3D printing world:)

Well, this small improvement may not deserve a full campaign, like the awesome mini hyena, but still what do you think what would be an adequate price for it?

If you have a thought about pricing, or more what price is it worth for you, just put it in the comment. If we can agree on a sane pricing, I will list at that price on the webshop:)

Lets do it folks!

Update:
Some of you were wondering how much flesh rest at the bottom of the groove.
So I destroyed one for ya:)

And here is a better view from the front:

Im not worried about wall thickness here, it is imho pretty strong still.
If you have any other question just shoot it in the comments:)

It has been a long time since I announced v3.0.

The new features:

• - Hot-zone is completely metal.
• - high temp extrusion should be possible, like pp, hdpe, plexi, polycarbonate, nylon (hopefully, this will be confirmed within a month)
• - shorter, more compact, a comparison photo between v3.0 and v4.0:
  
• - easier to assemble
• - reworked nozzle
  
• - laping for wrenches on nozzle, on stainless steel, heatsink
• - built for easy maintenance
• - self cleaning (you can remove the hardened plastic using two wrenches:)
• - built with dual extruder in mind
• - mounting compatibility for the average/stock reprap hotends
• - 100k thermistor (which seems to be a more common preference)

For assembly instructions please read here:
http://wiki.arcol.hu/arcol-hu-hot-end-v4-assembly

Regressions/future adaptations:
Dropped compatibility for Rapman, Makerbot. A new mounting needs to be designed for these machines.
For rapman a 200k thermistor also needs to be sourced to be electrically compatible.

I call it the hyena, because hyenas have the strongest jaw of all mammals.
All teeth are cut individually:

Here is a comparison photo with one of my hobbed bolts:

The brass one is the new version:)
You mount it with a M8 nylock nut, so the width of your extruder does not matter.

Key advantage over the old version

• It's machined from straight, round brass stock. Regular bolts often have large tolerances and are not entirely straight. The hyena is guaranteed to be straight.
• Each tooth is individually machines, so there is no "orphan tooth". An orphan tooth is an incompletely cut tooth that occurs during hobbed bolt production with a tap, because the teeth of the tap do not match the diameter of the bolt while cutting. This is a problems because it's the spot where filament begins to slip. It tends to bite a small piece of plastic off the filament as it does not reach deep enough to grip. The next (normal) tooth continues eating into the filament, resulting a complete filament strip, and no printing. The hyena prevents this by making sure every tooth grips by the same amount.

Installing on a Wade style extruder

Some pictures, from the top:

Also when opened (please note the washers around the bearings!):

(Also take note the really useful and special M8 nut. It will be the subject of an another announcement:)

Im a technical guy, any drawings?

Here it is:

Enough talk, I want one!

I was one of the people who ordered an original Arcol.hu Hot-end v3.0 and received it last week.
Laszlo had some problems with the production of the parts and delivery tooks some days more than planned , no problem for me.
The hot-end arrived completely assembled and was ready to installing
on the printer.
Mounting some connectors, calibrating the platform height and the machine was
already back in action. Assembling is so easy, like an IKEA furniture.
The first print was of course the simple raft prints for exact
adjusting the platform height.
The first that I noticed, that the heat-up time was very short, about 150 sec (the old BFB hot end took 4-5 minutes).
Direct after heating up the smooth running off the extruder en the smooth stream of ABS out off the 0.5 mm nozzle.
Then the real test was a part, what I needed for some days already.
During the first minutes of the printing, I surprised rather positively:
The bottom side of the part looked 100% good.
I never had that before and I didn't make any adjustments in Skeinforge to achieve this.
The printer ran so great that I sat down to watch the TV.
I did some quick checking during the print, and how the part growed over time.
I noticed some minor fault but that was not a problem with the hot-end
but with the extruder.
Afterwards I found out that the reel was falling during the print and
that caused some problems with the filament
The part was on all side perfectly closed and even the actual
dimensions were very good.
The max deviation was 0.15 mm. Even holes for M3 were perfectly round and open over 20 mm length.
The stringing on the part seems also less than before and while the printer was waiting for small temperature changes in the programs the was almost no ABS leaking out the nozzle.
The short heating zone is funtioning as it was meant to be.
The heater element, the resistor, is also very capable in controlling the right temperatur. +/- 1 degree is max deviation I had on the display during an 2 hour print (no I was not looking at the display for 2 hours

And then again:
It was announced as really big but is the hot-end V3.0 so big and so good ??

No it is not so big. It is a small hot-end in dimensions but with a great, very great results. It prints fantastic !!!!!! The announcement was too small for this hot-end.

A great job Laszlo !!!!

Author: Tiny

The pictures for the article:

Mounted view one:

Mounted view two:

Printed view one:

Printed view two:

Printed view three:

Mounted using some washers:

Printed Dice:

I later read on a forum (I've forgotten which one), that the printed replacement part will break as it could not possibly be as strong as the original one. That did had some truth to it...

My blender did break again. It only survived for long enough to make 11 banana shakes, and I now know, why the original part was made of rubber rather than plastic. The top and bottom part of the blender are not aligned with each other, so the rubber "gear" was acting as a flexible coupler to compensate for the error in design.

My print was made from black ABS, which is, of course, rigid. Thus it was doomed from the start.

The correct solution would be to print the part from flexible plastic. I was lucky to receive some soft pla samples from Kaipa, which has the consistency of chewing gum when printed. It was a perfect candidate for a flexible replacement part, and with my new Arcol.hu Hot-end v3.0 I was finally able to print with it:

I used the support option to print the part, as you can see in this photo:

Here is how it looked right after I removed it from the bed:

I cleaned it up using a knife. Here is how it looks from the top:

and from the bottom:

(I didn't remove all of the support material, as it has no effect on functionality.)

I tested the elasticity. Here is the part bending when compressed:

It springs back to its original shape when released:

I assembled it the way I described in my previous post:

Here is it mounted on the top part of the blender:

I do hope this one will last much longer then the previous version. The blender is not of very good quality, so I would be best of buying a new one, but I expect this repair last another year with my limited usage.

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 Arcol.hu 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.

Improvements

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:(

This is a dummy model of Arcol.hu Hot-end v3.0 to get a feeling of the actual size. A real hot-end cant be printed using plastic:)

You can print out this plastic Hot-end model to get a feeling of the size, or better adapt to your own machine.
The mounting and the size should be correct. Here are two photos, one of the openscad model and the other of the real world thing:

In reality:

And also from bottom, openscad:

In reality:

I also published it on thingiverse, as thing:4632.

Have fun!

For those who have missed, there were some previous prototypes, namely v1.0 and v2.0, and also v2.1, v2.2, v2.3, v2.4 and v2.5 what I have not published, and also many more trial, just I didnt brother to versioning them.

So what was wrong with the previous prototypes?

Well, it worked great for 2-2.5 hours, but after the filament melted upward in the hot-end that the extruder could not push the plastic anymore. So I sit back to the drawing board, and I redesigned it.
The new prototype works so great, that it melts about 10mm of the filament in total.
Here is a comparison photo for the non-believers;-)

This is a real problem on many extruders, hot-ends. I had many problems before with my Rapman machine.

Mounting on different machines
Rapman
That was the main reason, that I designed this hot-end as a drop-in replacement for Rapman machines:

Still some spacer disks required to make the hot-end longer, as it is too compact for the Rapman machine. I think fewer spacer disks are enough, just didnt have shorter bolts at home.

Mendels (standard and Prusajr variation)
And also basically this mounting is the only one, which have adapted to Mendel, and also Prusajr Mendel variation has mountings by default for this hot-end.

Im also working with Kliment for adapting the mountings for Makerbot machines. (Kliment: your parts are already lasercutted!;-)

Heater block

I reduced the nozzle mass so great, that it requires less then 2 minutes to heat up this nozzle on a standard Rapman machine! (usual warmup time is about 5 minutes, but I need to verify it with a stopwatch. I will update the article with proof-videos)
Here is a picture:

Please note, this heater block was handmade from a previous prototype, the mass produced hot-end will have a much more beautiful one, like this:

(the picture is taken from the upcoming assembly manual article)

Nozzle orifice

The current prototype has a 0.35mm orifice:

But I also have manufactured two 0.5mm ones.

Wire relief

The wire relief was improved further since the previous prototypes (section 6. in that article). Picture:

It protects more the thermistor, and also it prevents further against unscrewing.
(The hot-end is manufactured in a way that it prevents unscrewing by default, but some more (unneeded) security is always welcomed;-)

Heatsink (cold part)

I added more heatsink to further improve cooling of the filament. Maybe it is not necessary, as the filament does not melt upwards, but I like overengineering this part of the hot-end:

Also I additionally put a heat insulator at the bottom. The holding spacers act in this design as a heatsink, while in the previous design they were the major source of trouble because of conducting too much heat upwards. (And its the weakest point in the Rapman stock hot-end design).

Dogfooding

I was able to print parts, what I was unable to print with Rapman before (with 0.5mm orifice):

That part is 200mm long.

Im printing with this hot-end since this sunday, and there were no problem with it. Starting the extruder at the other day (so there are som filament already in the extruder) cause no problem at all.

I need to finetune skeinforge for 0.35mm orifice, and also in general, because my parts looks ugly, but it is not because of the hot-end! It prints really great:

Final image

I have three prototypes now. Two additional were manufactured:

These two have 0.5mm orifice, and also much nicer heater block. The final version will contain some more little touches here and there.

Introductionary video

I compiled a short introductionary video:

arcol.hu hot-end v3.0 from arcol.hu on Vimeo.

(sorry for my crappy accent)

I want this hot-end, how can I order it?

The best is droping an email to order (at] arcol.hu with your address. Shipping is possible worldwide, payment via paypal. If you have any question just ask in that mail.

I will also put hot-ends on ebay too, for those who want to licit against each other.

For preorders the price will be ??EUR with ?EUR shipping, I will ship them next friday (nov. 5), if nothing bad happens. For ebayers, it will be more expensive I believe.

So anybody ordering the hot-end (by email) until next friday can have this price.

I do believe this is an exceptional deal for this great hot-end. Also remember further nozzle can be ordered in the future if you dont like the current one (different orifice, different inner structure, etc).

Im really proud of this hot-end, I think I incorporated all of the plastic knowledge into this (at least my knowledge;-).

Shipping to different countries

If you can pay via paypal or wire transfer, I can ship it to you:)

The ?EUR shipping price is valid worldwide. No matter where you live in Europe, or the US or even Australia.
It is an introductionary price, so be wise, and order it now!;-)

Todos

Well I need to write an assembly manual for it. (I already took 110 pictures of each step yesterday during assembly).

And also publish design files on thingiverse, and fill the wiki.

Other announcements

I have started a wiki page, about all stuff what Im selling at wiki.arcol.hu.
I will keep that page up to date. So if you want more info before buying anything, you can look up there.

Im working on a webshop software, but currently ordering is possible via email, or bidding on ebay. (seller is "arcol.hu")

I hope you enjoyed the ride, and you like the resulted hot-end!

Update: I erased the introductionary price to not confuse people.

When you build more then 20 hot-end, you will break sooner or later a resistor anyway.

I had a choice to sacrifice the heater block or the resistor.
So I choosed the resistor, and I salvaged the heater block:-)

But if you have only a few, or maybe only one, that it is nice to know how much care is needed when you handle them.

Maybe some of you are interested what is inside in this power resistor and how it was made.

At both end there is closing caps, where the internal heater strip/wire and the outer connection mets:

At the middle there is a ceramic cylinder, where the heater strips is wounded around:

Between the two caps, there are some outer ceramic coating,
so the round wire resistor will never be perfectly round,
because at the two ends, the caps are always wider diameter then in the middle.

In reality there is a 0.1-0.15mm deviation in diameters.

Also you can easily pull off the caps (griping the wire with a pliers), and destroying the resistor.
Also the heater strip/wire is only coated with one or two layer of insulating paint, so if you force
the resistor it will likely crack exposing the heater wire to the outer world looking for possible
short circuit;-).

So my advice is:
If your resistor goes into the hole with a gently force, then fine, but never push hard into.
Dont pull, push twist the resistor with a plier.
If you cant push the resistor by hand into the hole, then drill out the hole with 0.1mm wider
drill bit and wrap the resistor into aluminium foil, then push it into.

Observe how thin is the coating around the heater wire:

Hope this article was useful for some of you.

Stay tuned to my next announcement!;-)