Is a sub 1 min 3dBenchy possible? Hotend Build and First Print! (Episode 2)

This old Tony just released a video about gas struts explaining how they have constant force! I doubt you can find one with a low enough stroke or spring rate but it’s a possible option to overcome the spring rate issue. Best of luck, keep it up 👍

I appreciate how you grounded the mains hotend heater. Good job with safety. 😁

This has to be one of the most creative designs for a printer I have ever seen.

A few ideas: 1. try and get all four to join a single point, a cylinder. Please take a look at the Maslow 4 CNC for reference. 2. instead of going for a constant force spring, connect the two loose ends of opposing corners via pullies, and a single spring between them. 3. make the filament path much longer, but shallow. make two parts with the same thread pitch, one male and the other female, with the max diameter of the male equal to the min diameter of the female thread. essentially a helical path with plenty of surface area to transfer heat.

Hi, I commented on your shorts about 300mm³/s. I have designed a few hotends and am currently pushing 120mm³/s with a single filament. A couple of tips: 1.What you said about "too much puddle" inside a very long hotend is true, to an extent. If the internal passage is 2mm or less, there is not much problem, retraction still works (imagine a Syringe, it can bbe as long as you want). Only issue is if you sit still for a long time the whole hotend will leak out, which is a lot of filament if your hotend is 250mm long for example. What causes problems is internal voids larger than 2mm. I experimented with 2mm entry hole opening up into a wider chamber of 3 or up to 5mm before tapering back down to 2mm and finally 0.8 or whatever nozzle size, and this is a huge fail. Completely inconsistent, you send 20mm of filament into it and nothing comes out; so you send 10mm more into it and 30mm comes out, very bad. But if you maintain 2mm or even slight taper down 1.75mm or less, there is no big issue. I have tried this up to 200mm hotend length. 2. I think your hotend has way too much thermal mass. What you made is something from industrial extrusion, that could melt KGs of filament all day at consistent rate but that is not really appropriate for 3D printing. You built a jumbo jet when what you need is a rally car. A 3D printer needs to be "light weight" or "nimble" in terms of thermal mass. It needs to be able to go from 0mm³/s to 200mm³/s in the blink of an eye, and back to 0 just as fast. That giant mass of yours will take a long time to respond to changes in heating load. My hotend currently is 3 Zones in series (single filament), each is a 115W CHC heater, very light, almost no thermal mass, they respond instantly to change in demand. Within a few mS of sending a huge volume purge command you can see the output jump from 0% to 100%. The series multi-zone concept is also how slice Engineering are powering their Prime hotend, and also how industrial extruders work. If you stick with that much mass controlled by a single output you will see latent temperature drop many seconds after demand starts, by which time it will be too late and temperature will continue dropping even though your band heater is now dumping all of its beans into the heater block (and then it will overshoot and burn the filament). 3. You can get mica sheets for cheap that make excellent insulation between your cold end and hotend. Very light weight and easy to cut to size. I get mine on amazon. 4. Since your hotend is connected to your coldend by a huge bolt, you might be able to cut through the heatbreaks. I dont think you can eliminate them entirely but cutting a slot through them with a hacksaw would sever the thermal path and unless youre going to run 60A TPU i dont think the filament will find its way out through the cut.

"spring" with constant force is a vacuum. you can machine airtight cylinders with pistons that you can use as springs, and force of the spring will be determined by area of the piston

The fact it printed anything on first try is super impressive. I built a coreXY based on standard plans, and it was probably 20 tries before i got a print that made it to 80% finished 😂

This is a great project! Very interesting to see the failures, dont shy away from showing them as it allows us to learn from them together. Keep going man, I subscribed and looking forward to the next one.

Constant force spring you can try....quill spring from a drill press. Cheap and easy to find. Mcmaster Carr has lots of constant force springs. You can also find them in tape measures

Hi, i have some thoughts about this project i wanna share with all of you. Maybe some of my ideas are usefull, others might be not, but a discussion is always good. 1. For cooling the hotend, you could use an old water cooling from a PC. These are cheap and in combination with a costum made coolingblock, you will have a capeable system. Also you can than change your cooling effectiveness, by simply changing the speed of the fan that is sitting on the radiator. 2. I have never seen this before, but in theory you only use retract in a normal FDM printer, to decrease the pressure inside the nozzle. Therefore the friction between the molten plastic and the walls of the nozzle is strong enough to prevent a leakage of filament. So in order to make a fast extruder, with a long heating zone for the incomeing filament (this would have benefits you have mentioned in the video) we need to make a design that can rapidly decrease the pressure inside the nozzle. Furthermore i would suggest useing a small stepper motor and a moveing "wall", so you can adjust the volume of the nozzle really quickly. This comes with a lot of challenges like: sealing the entire nozzle setup, so no filament can clock up the motion of the wall; building a system that is light weight enough to not disturb the motion of the z-axis; create a mechanism that can withstand a constant pressure of up to 300 bar in inside the nozzle. So it is hard, but might be a good idea for this use case. 3. As some other comments suggested already, you could use a vacuum system for your motion system. However i would recommend a magnetic system instead. A combination of permanent and electronical magnets could solve this issue while also being more reliable and faster than the vacuum system. Let me explain: 3.1 The permanent magents would be used to create a constant tension on the ropes so they dont slip. 3.2 The electro magnets would be turned on and off individually depending on the current motion of the build plate. This would result in a stronger force and an even faster accelleration. In my opinion it is also easier to build such a system in comparison to a vacuum based one. 4. Consider useing a laser 3d printig method for manufactoring the hotend. By drilling in a solid block, you will always find some sharp edges inside, that you cant get rid off. But these increase your friction. A good laser based 3d printer can print this part with a higher precision due to lower tolerances. Nun nochmal auf Deutsch, da du ja augenscheinlich der Deutschen Sprache mächtig bist ^^ 1. Für die Kühlung der Heatbreak würde ich an deiner Stelle eine alte Wasserkülung mit 120 oder 240mm Radiator verwenden. Damit hast du definitiv genügend Kühlleistung. Auch kann durch die Regulierung der Lüfterdrehzahl auf dem Radiator die Kühlleistung angepasst werden. Wenn du kleine Schläuche, mit jedoch einer hohen Durchflussgeschwindigkeit wählst, sollte auch das Gewicht des Teils nicht alzu große Auswirkungen haben. 2. Um das Problem mit dem Filamentfluss zu lösen. Ich habe überlegt, wie man es schaffen könnte ein langes Hotend zu verbauen und gleichzeitig gute Retractwerte zu erhalten. Da wäre ein System das das Volumen innerhalb der Düse anpasst natrülich ideal. Ein Steppermotor oder Servo könnte ja einen kleinen Teil der Wand bewegen und so das Volumen vergrößern, wodurch der Druck in der Düse abfallen würde. Dann würde auch kein FIlament mehr aus der DÜse gedrückt werden und du hättest ein sauberes Ergebnis. Das System habe ich so noch nie gesehen und schon in der Theorie ergeben sich für mich da ein paar Probleme. 1. Wie schafft man es das ganze richtig abzudichten, sodass diese bewegliche Wand nicht verklemmt. 2. Wie schafft man es den Druck der (ich meine es mal gehört zu haben, aber sicher bin ich mir bei dem Wert nicht) bis zu 300 Bar innerhalb der Düse erreichen kann aufrecht zu erhalten (also die Mechanik so stabil und gleichzeitig leicht zu bauen). 3. Was passiert wenn der die Extrusion wieder fortgesetzt werden soll? Man könnte den Stepper Motoren die das FIlament einführen zwar den Befehl geben kurz anzuhalten und gleichzeitg die bewegliche Wand wieder zu schließen, sodass das "überschüssige" Filament in der Ausweichkammer aufgebraucht wird, aber das könnte auch in der Praxis zu Problemen führen. Das müsste man testen. Trotz alledem wäre es sicherlich das spannenste Teil am ganzen Drucker! 3. Wie andere schon beschrieben haben könnte man ein System nutzen das mit Vakuumpumpen funktioniert. Jedoch bin ich kein Fan davon. Es ist sehr schwer 4 Zylinder zu bauen, die Luftdicht sind, aber in denen die Reibung gleichzeitig gering genug ist, um wahnsinnig schnelle Bewegungen auszuführen. Auch ist es meiner Meinung nach nicht möglich eine gleichmäßige Kraft in jedem Zylinder in ultra kurzer Zeit aufzubauen, um so die Seile im richtigen Moment zu spannen. Klar, man kann die Zylinder permanent unter Vakuum setzen, jedoch arbeiten dann die Motoren ständig gegen diese hohe Kraft an, was den Strombedarf erhöht und unnötig Leistung zieht (erhöht dadurch auch die Temperatur der Motoren, die dann zustätzlich abgeführt werden muss). Stattdessen wäre es meiner Meinung nach sinnvoll ein System mit Magneten zu bauen. Wenn man Permanentmagneten verwendet, kann man denselben Effekt wie jetzt mit den Feder erreichen. Jedoch bin ich der Meinung das es am besten wäre zusätzlich, kleine Elektromagnete zu verbauen, die im richtigen Moment (wenn Spannung im Seil zu niedrig ist, eine lange Wegstrecke zu fahren ist, oder einfach um noch schneller die Platte bewegen zu können) zusätzlich die Kraft auf das Seil erhöhen und so die Motoren unterstützen. 3.1 In dem Zusammenhang fällt mir gerade ein, dass es sein könnte das das Druckbett minimal in der Höhe vibriert. Dadurch könnten zukünftig auch Druckfehler auftreten. Das könnte man jedoch lösen, indem man die Motoren mit einem leichten Gefälle auf allen Seiten anordnet, sodass quasi zusätzlich von jeder Seite leicht nach unten gezogen wird. 4. Das Hotend mit der Düse konnte ggf. mithilfe eines Micro SLS Druckers gedruckt werden. Damit lassen sich sehr genaue Toleranzen erreichen. Somit entstehen anders als beim bohren keine scharfen Kanten und noch glattere Oberflächen innerhalb der Düse, wodurch der FIlamentfluss verbessert wird. Auch kannst du so das Teil direkt aus Titanpulver herstellen lassen. Ob das am Ende preislich sinnvoll, und überhaupt notwendig ist ist abzuwägen. Generell gilt, ich wollte dies Ideen einfach teilen. Vielleicht sind sie doof, aber vielleicht auch nicht. Zumindest drüber nachdenken kann man und vielleicht bringt es ja einen dann auf die richtige Idee für das jeweilige Problem. In jedem Fall bin ich gespannt wie diese Projekt weitergeht und was so die Lösungsversuche sein werden :)

When it comes to part cooling, seeing as the hotend only moves up and down have you thought about a wind tunnel around the whole contraption. That way you can suck most of the heat out. Hey a prints a print when everything is built from scratch. I just can't wait for the evolution of this.

Its so satisfying to see this level of engeneering and using maschines. Stunning job, thank for sharing! Greetings from Austria!

For the tubes going between the hot end and cold end, you can buy medical thin wall tube in stainless for sure, maybe also in titanium from the right supplier. Saves you having to turn tiny tubes

This project is turning out really impressive! Super excited to keep watching this series.

Brilliant! Under a minute! Almost there - all that’s left is shape! Keep it going

Hey. Awesome Project. Regarding the constant-force "spring" system, I know it would be too much trouble but you could use a counterweight system through a series of pulleys and hang the weights at the edge of the table. This system would also be easily adjustable but definitely hard to implement. Also, one reason for plastic oozing out of the hotend from heartbreak connections could be the different thermal expansion rates of Aluminium and SS causing a gap in those connections resulting in material oozing out due to nozzle backpressure. Since the hotend isn't mechanically constrained relative to the heatsink, It is allowed to freely expand and I think this results in a gap. One possible solution would be to heat-press them together. To adjust the filament feedrate, one easy hack could be to use 2*1.75mm = 3.5mm filament Diameter in the slicer which would give you 4 times the surface area similar to running 4 extruders at once. I also think that using a material like ABS with a higher melting range (around 100C) would allow you to increase the temperature of your heatsink without melting the material in there which would result in the filament requiring less heat to get to a printable state in the hotend. Best of luck and thanks for sharing this process.

I love how so much of this system is new knowledge to me. Very interesting to follow! Also don’t mind the length as its chill to watch while I am tuning my RatRig 3.1 500x500

failures are the building blocks of success. The way you challenge and provoke, the way you think out of the box, impressive. I look forward to the many twists and turns this project will provoke. Love your den.

Thoroughly impressed. Very cool idea for the whole printer.

Totally awesome, can’t wait to see what quality you will be able to get from this thing