High-flow 3D printer nozzles are in my opinion one of the most important additions to 3D printing of the last years because they are able to melt material way more quickly at the same size as a standard nozzle. No more long, unstable hotends and custom fan shrouds. E3D released their REVO hotend system over a year ago which is great if you swap nozzles regularly yet it uses custom and design-patented nozzles so you’re only able to use their nozzles. And this was a serious problem and the reason why I replaced the REVO hotend on my LDO VORON 2.4 with a Phaetus Rapido at some point. In the beginning, E3D only sold brass nozzles for Revo, so I wasn’t able to work with abrasive filaments, and they didn’t offer any high-flow options. Their abrasion-resistant ObXidian nozzle finally started shipping some weeks ago and we now also have REVO High Flow where E3D teamed up with Bondtech to bring the Core Heating Technology to REVO. Links to both are down in the description if you want to pick one up!

*Get Revo High Flow (affiliate)*

High Flow Nozzles: https://geni.us/RevoHighFlowNozzles
60 W Heater Cores: https://geni.us/Revo60WHeater
ObXidian Nozzle: https://geni.us/ObXidian

*Other High Flow Options (affiliate)*

Bondtech CHT: https://geni.us/BondtechCHT
Bondtech CHT Volcano: https://geni.us/CHTVolcano
Bondtech CHT Hardened: https://geni.us/CHTHardened
Bondtech CHT Hardened Volcano: https://geni.us/CHTVolcanoHardened
Phaetus Rapido: https://geni.us/Rapido
Slice Engineering Mosquito Magnum: https://geni.us/MosquitoMagnum

When I saw the first images of the internals of that nozzle, I was really intrigued because it looked even more fancy than Bondtechs CHT design. The only way you’re able to spot if you have a REVO High Flow is of course the marking, but technically more important this small line that you’re seeing at the bottom of the nozzle. The fancy internal structure is not metal 3D printed, but the high-flow portion got press-fit into the nozzle body. And this brass slug with the teardrop dome and the 4 bores that go to the tip makes all the difference.

The amount of material you can melt in a 3D printer's hotend is, in most cases not limited by the amount of heating power that your hotend has. Polymers are quite bad conductors of heat. So even though your nozzle is super hot it takes a while until this heat traveled into the inside of the filament to properly melt everything. In the past, high-flow hotends were just longer like the well-known Volcano hotends, so the filament stays longer in the meltzone. In E3Ds high-flow design, the filament gets expanded over the dome structure, and this has a bunch of benefits. First, the material section gets thinner - from my reverse engineering to around 1 mm from the initial 1.75 mm, so it takes less time for the heat to travel to the inside. And since the inner dome is connected to the rest of the nozzle, it now also heats the material from the inside, hence Bondtechs or rather 3DSolex Core Heating Technology. After the dome section, the molten material gets channeled back to the nozzle tip with 4 separate bores before it leaves the small orifice. This sophisticated internal structure results in almost double the surface area that touches the plastic and over 60% more time for the filament to pass and also melt in the nozzle. I know this sounds like a sales pitch, but at a price of around $45 - 50 each it definitely needs one, and we’ll test if it holds up to its claims in a second.

And now back to E3Ds new REVO High Flow nozzle. Let’s try it out and see how well it performs. I, of course, wanted to compare it to Bondtechs CHT nozzle but since you can’t screw a standard nozzle into a REVO I had to use a trick. By coincidence, a viewer from Mexico named Matias send me a prototype of one of his REVO to V6 adapters, that he recently launched on Indigogo. This is not an endorsement of this product because I had my fair share of leaking and installation problems with it, but I tried to give Matias some feedback and advice to improve the retail version, and maybe some of you might be interested as well. I did all my tests on the LDO Voron 2.4 using the Clockwork 2 extruder and some VOXEL PLA at 220°C nozzle temperature. Currently, I only have the 0.4 mm version of the REVO High Flow so this is what I tested and compared to the regular REVO and Bondtechs CHT.

The flow test is quite simple, and I extrude this meandering structure at higher and higher speeds until we can see extrusion problems. I started at 5 mm³/s which is around 50 mm/s printing speed at 0.2 mm layers and increased the extrusion rate by 1 mm³/s every mm of print height. Our reference, the normal REVO nozzle started misbehaving at 14 mm³/s which would be around 150 mm/s printing speed, where you can already see that not everyone needs a high flow nozzle. You can always check the flow rates of your prints in your slicer preview by the way! The failure mode is really interesting because we can see these bulged corners which is a sign of insufficiently molten filament that’s more like rubber when it leaves the nozzle and then contracts again leaving you with this kind of phenomenon.

Let’s now check how well Bondtechs CHT performs. I installed it into Matias V6 adapter but had a ton of material leak at first because with my sample, he tries to seal at the hex and not at the bottom, which is in my opinion a very bad idea and I hope he’s going to fix that. Don’t tell anyone, but I used some Teflon tape to seal it which did the trick. This setup has the advantage that the meltzone is longer because it sticks out, yet, on the other hand, it’s not properly insulated which might reduce extrusion temperatures. I temporarily insulated it with some Kapton tape but still take these results with a pinch of salt. The CHT performed 60% better than the stock REVO with a maximum flow rate of 22 mm³/s where the extruder motor started skipping which resulted in holes in the outer wall.

Let’s finally test the fancy E3D Revo High Flow. It performed the best and increased the flowrate capability by almost 70% compared to the reference achieving 23.5 mm³/s which would be 260 mm/s printing speed at 0.2 mm layers and therefore even beating the CHT. This shows that the complex internal structure even improved Bondechs already ingenious design, yet with a definitely higher manufacturing effort. According to E3Ds blog post, the bigger size nozzles should perform even better, yet since I don’t have any, I can’t confirm this myself.

I also did my blob or poop test, which tells us even a bit more about a nozzle's performance.

The results were pretty similar with a maximum flow rate of 16 mm³/s for normal REVO, 22 mm³/s with a Bondtech CHT on an adapter, and finally 24 mm³/s for the new REVO High Flow. This test also showed how consistently E3D’s new high-flow nozzle works in a very wide flow range because it only really drops off, once it reaches its maximum extrusion rate.

If this has an impact on print quality is something we’ll take a look at as well, but before that, I also have to talk about E3D's new 60 W Heater Core. If you buy a regular Revo it comes by default with a 40 W heating element, which is sufficient for all the standard flow nozzles. The 60 W version is another roughly $50 accessory. But do you really need it? Well, I did all of my tests with the 40 W unit because I’m certain it has enough power for even high-speed printing with the 0.4 mm nozzle. And here is the proof. Mainsail, the interface that I use for Klipper on my Voron 2.4, can show you the duty cycle of your heater. Hotend heaters are usually PWM controlled which means that they are turned on and off in very quick succession to adjust the power output. The ratio between on-time and off-time is the duty cycle. And this info is displayed in Mainsail which shows some really interesting data. I wrote down the maximum duty cycle during the extrusion test, and with normal REVO it used 63% heater power at 14 mm³/s. With the CHT it used 73% heater power at 22 mm³/s and with the REVO High Flow the heater was on 71% of the time at 25 mm³/s flow rate. So, even at maximum flow, we only use ¾ or 30W of the available 40W heater block power.

But wait, why are only using 13% more heater power at a flow rate that is 80% higher? Well observed! So the power that you put into your hotend is not only used to melt the plastic. Some of it also just dissipates away. There are several different paths where your heat goes on a hotend besides melting the plastic. First, there is heat conduction through the heartbreak. Then there is natural convection and radiation of the heater block itself. Once you turn on part cooling you’ll additionally have forced convection because some air actively flows over the nozzle and the heater block. So to get an idea of how much energy simply dissipates away without melting anything, I did some stationary tests. I increased the hotend temperature in steps, with part cooling on and off, and very interestingly also with and without the silicone sock. So in the optimal setup without part cooling and the sock on the hotend, it used 19% heating power at 180°C and 39% at 290 °C. With the sock removed it only needed slightly more power. It becomes more interesting when we turn part cooling on because then we already require 33% heating power at 180°C and a whopping 65% power at 290 °C to only hold the temperature without any material that gets molten. Removing the sock also has a huge impact because it increases the energy consumption to 41% at 180 °C and 82% at 290°C which leaves almost no more headroom for melting plastic.So make sure not to lose your socks!

If we combine these numbers with the extrusion test we can calculate that we need roughly 1% heater power or half a W per mm³/s extrusion rate. This is a good value to keep in mind! This for example means that your heater only uses 5 W of its power at an already decently fast 10 mm³/s flow rate for melting the plastic. The rest just gets dissipated as heat. And I of course performed some flow tests, where the difference between the two heaters for the 0.4 mm nozzle was negligible. All of these numbers show that if you primarily plan to use the 0.4 mm REVO High Flow nozzle, you don’t need the 60 W heater core, and even with the 0.6 mm nozzle most won’t really need it. Only at even bigger diameters and printing high-temperature materials, the 60 W core will become interesting and necessary. Yet if you get a completely new REVO you can opt for the higher-power heater because it makes the nozzle heat up ever more quickly and gives you a bit more headroom in difficult situations. Since I have one, the 60W core will be my new daily driver on Revo.

So we have seen that E3Ds new High Flow nozzle significantly increases the flow capabilities of the REVO ecosystem, but is it a drop-in replacement or does it result in worse print quality if you print slowly? The answer is pretty simple. I printed some models in PLA with the standard, and the high-flow REVO and the results were basically indistinguishable. Surfaces looked the same, stringing was the same, and overhangs looked similar. So at least for this material, it doesn’t really matter, and I see no reason why you shouldn’t use E3Ds new REVO HF as a replacement. Yet, I didn’t test all materials and know of reports that people had problems with Bondtechs CHT and some materials like TPU, so do some research before you buy a high-flow nozzle for a non-standard application.

In the end, does this mean that you should get a new REVO High Flow right away? If you already have a REVO hotend installed on your machine and want or need to print faster, this is finally the option we’ve all been waiting for. From the tests I’ve done it at least performs as well as Bondtechs CHT nozzle and delivers more melting power in the same package size. If you mainly print with 0.4 mm nozzles, you should ask yourself if you really need it because a regular nozzle only becomes the bottleneck if you’re going over 150 mm/s printing speed. If you often print with 0.6 mm and bigger, then Revo High Flow quickly makes sense, and at some point, you’ll also have to upgrade the heater core to the 60W version. On the downside, these new multi-part nozzles are quite expensive and at $45 bucks are something you should think about twice when buying.

And then it’s the abrasion-resistant problem all over again because High Flow is currently only available in brass and therefore not suitable for any abrasive materials. And talking about particles. One thing where I’m a bit concerned about is how easily you can clean this nozzle when it’s clogged. Cold Pulling is straightforward on a regular nozzle and with some practice also doable on Bondtechs CHT nozzle. Yet, so far I was only able to Cold Pull a Revo High Flow once and I’d call my self quite skilled in Cold Pulling. E3D also says it’s possible but be prepared for some headaches when you get something stuck in your precious nozzle.

If you regularly switch nozzles, and honestly I do this now way more often ever since I got Revo, the REVO ecosystem is now finally complete, and I can recommend it for most applications if you’re not on a budget. Yet if you are looking for the best-performing hotend purely in terms of flow rate then Revo High Flow isn’t the one you should get because it’s still limited by the length of your meltzone. A Rapido High Flow or even Ultra High Flow for example has a significantly longer melt zone and if you additionally install a Bondtech CHT in there, it will outperform Revo. Links to other high-flow hotends as well as the new Revo High Flow nozzle are down in the description that help me pay the bills right here. But what are your thoughts on E3Ds CHT? Would you have expected that they team up with Bondtech and would you spend almost $50 bucks on a brass nozzle just for more speed?

*Get Revo High Flow (affiliate)*

High Flow Nozzles: https://geni.us/RevoHighFlowNozzles
60 W Heater Cores: https://geni.us/Revo60WHeater
ObXidian Nozzle: https://geni.us/ObXidian

*Other High Flow Options (affiliate)*

Bondtech CHT: https://geni.us/BondtechCHT
Bondtech CHT Volcano: https://geni.us/CHTVolcano
Bondtech CHT Hardened: https://geni.us/CHTHardened
Bondtech CHT Hardened Volcano: https://geni.us/CHTVolcanoHardened
Phaetus Rapido: https://geni.us/Rapido
Slice Engineering Mosquito Magnum: https://geni.us/MosquitoMagnum