Please make a Bondtech CHT hotend assembly

I am not entirely certain how possible this is since Bondtech currently holds the rights to the CHT technology. Maybe both Bambu Lab and Bondtech could co-produce a hotend assembly design that integrates their CHT nozzle that is compatible? Man, how I would love to see a speed run with one of these suckers!

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yes! This would have been number 3 on my list, except that was for software. My number 1 hardware wish is for a CHT nozzle. Just pass the licensing cost through to us. I would be more than happy to pay. The nozzle is the only thing slowing the Bambu down.

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Is the nozzle the only thing slowing things down?

Cooling is obviously often a problem, and the heater is quite small compared to many 3D printers.

The hot-end can already push through over 20mm³/s with most filaments; significantly more than many standard nozzle setups.

The extruder motor is specified with a max of 25mm/s, which should be plenty, but I think it’s relatively limited in torque which may also become a problem at high speeds.

I’d firstly quite like to see a brass nozzle first, to see what improvements that can make with its higher conductivity.

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You had to mention conductivity… I can’t help but find myself wishing for a Bambu Diamondback nozzle.

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Good catch! Well, there’s another opportunity for growth if the motor is another wall they would be running up against. At the very least, CHT nozzles do improve the quality of flow and not just the quantity since heating is more even and thorough through the filament core.

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CHT Nozzle have been the most important (and simple to do) improvement that I have seen since I began 3D printing.

As mentioned by other it is not only to increase flow, but also to make the temperature of plastic output as close as possible to nozzle temperature , this make huge imporvment when printing with different speed. Also this CHT nozzle, by its small size is a lot better than volcano or other kind of high flow nozzle as it react a lot faster to temperature change.

EDIT: IMHO this is a major (and maybe the only one :slight_smile: ) ingenierie mistake on this printer. It is like having a Ferrari car with a low cost car motor.

There is a hotend selling on amazon allowing you to change your nozzle…(https://amzn.to/3wgPKJo)

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Interresting, anyone tried this ? does not seems to have a lot of comments…

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I have one on order to try but i havent recieved it yet

Well I couldn’t resist too… :slight_smile:

In the meantime I found this video of Stefan that I missed on Volcano hot end on standar cartrige, very interesting, once again CHT beat them all, the flow of a Volcano without the inconveniences (like oozing more).

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I put a CHT nozzle on a magnum + and had to upgrade the extrusion motor to a chainsaw engine. It’s like a super soaker that fires off molten ABS.

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I did put a CHT nozzle on my Bambu Lab X1 printer and reached 40+mm³/s with PETG 0.4 nozzle

I ran into a bottleneck wall at around 35mm³/s and the printer gave me a thermal runaway error, as I was printing the hotend cooled down and was almost 20c under set printing temp when the 3 minutes runaway error kicked in and stopped the flow rate tower.

I won’t explain how I modified the hotend here though, this is totally not recommended and I am waiting for Bambu Lab ticket answer before sharing more about this.

But I did it

Haven’t even tried the 0.5 0.6 0.8 1 1.4 and 1.8mm nozzles yet, this is just insane potential

I’m about to design a much higher CFM and static pressure nozzle fan duct that also uses PWM

As can see there is a nozzle height z delta that makes the silicon sock not really hide the end of the CHT nozzle this can be pulled off a bit to hide a bit more a protect it from the nozzle fan air
Which needs a new design because the nozzle is a few MM under the default nozzle which makes the present nozzle fan duct ineffective and actually cool the nozzle end

The original fan very small very noisy not powerful compared to a new competitor

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Great ! 30/35mm³/s is largely enough if it can be kept constant,

In addition to being able to print with a 0.6mm nozzle and 0.3mm layer height, wich is for now useless as it take same time as 0.4 Nozzle with 0.28 layer height, really wonder why Bambulab sell 0.6 & 0.8 nozzles, the big improvment is that it should give a lot more consistent flow & plastic temperature. Did you experiment quality between print with and without this Nozzle ? like filament color/apparence changing between slow and fast move ? did you notice other improvment not related to printing even faster ?

PS: you say you dont want to explain how you did, but as mentioned above there is a kit seled online to use different kind of nozzles :slight_smile: , I’ll post feedbacks when I will have tried it.

EDIT :

As can see there is a nozzle height z delta that makes the silicon sock not really hide the end of the CHT nozzle this can be pulled off a bit to hide a bit more a protect it from the nozzle fan air
Which needs a new design because the nozzle is a few MM under the default nozzle which makes the present nozzle fan duct ineffective and actually cool the nozzle end

Fortunately this is probably the easiest silicone sock shape to mold using high temperature silicone

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Any news ? I now got the nozzle removable hot end, waiting for the CHT nozzle to be shipped :slight_smile:

Did you manage to set a new PID to avoid thermal runaway ?

EDIT:

For information here is the Nozzle that come with the replacement kit.

I am in touch with Bondtech to see what Nozzle could match or not the best, probably M6 RepRap ?

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I asked Bambu Lab in a ticket for the PID but got no answer so far…

Yes the RepRap size is the good one, I am using this size and fits perfectly

I did not experiment quality prints between different nozzle or hotend, I just measured the increased flow rate, everything else seems to be on par

Improvements: You can replace the nozzle instead of the whole hotend assembly, you get access to CHT and CHT clones and cheap hardened nozzle, tons of advantages so far

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The machining complexity of that would be nearly impossible in bambu’s all in one design. In my testing with 20mm long nozzles, multiple throats creates more drag than it helps flow. I have data to back that up. Long CHT is bad for flow.

Just because the heat block is small, does not mean the output of the heater cartridge is. Its 50watt which is bigger than most basic printers. The small mass means it can transfer the heat more efficiently to the bore where it is needed. IMO its one of the best designs.

The biggest bottleneck on speed is material properties. Many people do not have any clue that every PLA even between colors can have vastly different melt indexes which leads to wildly different rates of success at different speeds.

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40W IIRC, but you’re right, I was misremembering specs on others. It’s seemingly still more than most printers, even those pushing out high flow.

This is a little bit like saying, “we could extrude faster if people chose to extrude soup rather than plastic”.

For considering speed bottlenecks it’s best to just consider a pure base resin filament and work from there. Printers fundamentally cannot change the filaments that people are printing with, and there’s always going to be a compromise made with other material properties if more filaments are optimised for high flow printing.

Would you be able to share your test setup and the data you got from it?

This is just not enought to go over 35mm3/s (there is a video of CNC kitchen explaining that, it is not proportional), When I was triying CHT on Bambulab I was stuck at 35mm3/s because the temperature was not able to go over 220°C, setting 230°C it was sticking to 220/221°C when I was printing at 35mm3/s. But anyway it is still more than 50% improvment in speed, wich is already very very good.

I only tryied 0.6 CHT, am gonna order a 0.4 nozzle now :slight_smile:

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So the ceramic heater is 48W at 24V 12ohm
You’re about right, I’ve hit a bottleneck at around 35mm³/s on with CHT nozzle on the Bambu cloned hotend

As I was printing a speed flow rate tower, the flow kept increasing but around 35 the temperature kept decreasing, after 3minutes of being off the printer gave me a temp runaway error and stopped print, it was almost 20C under set printing temp because the cool filament was flowing too fast and actively cooling the hotend faster than the heater / PID was doing its job.

But some other user mentioned that with this hotend and CHT nozzle he did not have this temperature / heater issue, so I think this need much more tests

So… I’ve wired 2 ceramic heaters in parallel and put the second one on the other flat side of the hotend. This is not recommended at all and it might damage some electrical components, but it works for me, it heats faster and allows to bypass the previously mentioned bottleneck. I have a ticket with Bambu Lab, they do not recommend this but they recognize this might work as well, so do what you want with that

I can now reach above 40mm³/s with PETG

I am also about to design an external electrical circuit to allow 4 ceramic heaters on all sides of the hotend for super fast heating and no more heating issues

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Adding a secondary ceramic heater is a good idea if the motherboard can handle this power.

No problem with the heat breaker ?

I am not sure you will get enought power from the card for four ceramic heaters : 48W*4 = 192W it is a lot of power.

EDIT: and I really doubt the heat breaker will still be able to play its role

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