PLA waste bin in 73 minutes - insane melt rate
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Following on from my other posts about my 6 input multi-material hot end, I thought some of you might be interested to see the insane melt rate it is capable of when all 6 inputs are fed with PLA and the mixing ratio is set to use equal proportions of each one. This is a functional waste paper bin, using a 1.5mm diameter nozzle, 1.65mm layer width, 1.0mm layer height and a reliable continuous print speed of 80mm/sec (the extruders started skipping at 90mm/sec). It's only 7 minutes - watch to the end to see what the average volume flow rate rate was. https://youtu.be/gc8AciHjf4I
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If you were interested to see whether you can increase the melt rate with a Bondtech CHT nozzle, I'd be willing to sponsor you one. Your choice of nozzle diameter, but I'd be most interested in 1.8mm performance (-:
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@oliof said in PLA waste bin in 73 minutes - insane melt rate:
If you were interested to see whether you can increase the melt rate with a Bondtech CHT nozzle, I'd be willing to sponsor you one. Your choice of nozzle diameter, but I'd be most interested in 1.8mm performance (-:
It's possible that Bondtech might send me one - I have put forward that suggestion but they haven't been too forthcoming with such requests of late, so I'm not hopeful. Let's give it a few days and see what their response is. Feel free to PM me in a few days.
For comparative purposes, we ought to use a conventional nozzle of the same size as the CHT version. I have this E3D 1.5mm (that I drilled out from a smaller size) but the shape of the tip won't allow me to drill it any bigger. So I could easily test a 1.5mm CHT against this one, but if you wanted to try a 1.8mm CHT, I'd need a "conventional" 1.8mm as well.
TBH, I don't expect the CHT would make much difference because in my design, the filament is already molten long before it reaches the nozzle. But there is only one way to find out for sure ......
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@deckingman I'm happy to send you some CHT nozzles, send me a DM with what sizes you'd like and where to send them. Will probably ship direct from Bondtech since you're not in the US.
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@elmoret said in PLA waste bin in 73 minutes - insane melt rate:
@deckingman I'm happy to send you some CHT nozzles, send me a DM with what sizes you'd like and where to send them. Will probably ship direct from Bondtech since you're not in the US.
That's extremely generous of you. I'll message you later. Many thanks.
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@deckingman said in PLA waste bin in 73 minutes - insane melt rate:
the filament is already molten long before it reaches the nozzle.
Is it because of your two-stage heater?
Did you also increase filament temp when you sped up to 90mm/s? Maybe some temp-tweaking or heater-insulation would help?Anyway, with a nozzle almost the same diameter than the filament, it's unlikely to see a difference between brass and CHT, IMHO.
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@o_lampe Yes. The indidual filaments go through a "combing block" which in this case was heated to 195. Then there is a short section of about 3mm which, along with the nozzle is at print temperature (in this case 205). For sure, the melt rate could likely be increased further by using elevated temperatures. But the main purpose of this hot end is to be able to print multiple different filaments. The high melt test was just to demonstrate this bonus feature.
I do have this crazy idea of making a 2mm diameter nozzle. It wouldn't normally work with 1.75mm diameter filament but in this case, it might. Because I feed the 6 molten filaments into a 2mm diameter section just before the nozzle.
So much to do and only one lifetime in which to do it....... -
@deckingman said in PLA waste bin in 73 minutes - insane melt rate:
So much to do and only one lifetime in which to do it.......
Yeah, it's time for The Sorcerer's Apprentice. Maybe start a local Makers Club?
The Wizard of ooze just came to my mind
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@deckingman I did donate some money either way, @elmoret's offer notwithstanding -- spend it however you deem useful or frivolous; think of it as an early christmas gift (-:
The comparable CHT size to your 1.5mm one would be 1.4mm (-:
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@oliof Thank you so much! That's really appreciated and if it doesn't go towards nozzles, then it will either go towards tooling and materials for the next gen combining block that I have planned, or towards filament. 131.7 metres in 73 minutes equates to a linear filament feed rate of 1.8 metres a minute! - so it rapidly diminishes my stock levels. Or to put it another way, at that sort of flow rate, a 1Kg spool would last less than 3 hours.
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By way of open and full disclosure, I've just received an email from Bondtech offering to send me one of their CHT nozzles. They asked what size I wanted, to which I have replied 1.8mm because then I can make a direct comparison. When I receive it, I'll print that same vase again and see if I can increase the speed (flow rate) further. Given that, in this hot end design, the filament is already molten before it reaches the nozzle, neither I nor Bondtech think that the CHT nozzle will make much difference. But of course, there is only one way to find out......
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@deckingman it might still change behavior due to different backpressure. Thinking about it, it might be even worse with the CHT style .... but I am all for practical testing, so I'm looking forward to the results!
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@oliof One thing occurred to me, which is that with such extreme melt rates, a huge amount of part cooling air is required to prevent the part from collapsing into a semi molten blob of nastiness. Inevitably, some of that cooling air gets deflected back onto the nozzle, which is not necessarily "seen" by the thermistor. It is possible that a CHT nozzle might react differently to that deflected part cooling air (either better or worse). We'll find out in due course.......
