There’s little doubt that E3D is a world-leading extrusion system manufacturer, and the new Revo Rapid Change hotend looks to further that reputation. It’s currently flying off the shelves and appears to be a hit with the big reviewers, but there are a few niggles. As a part of our new partnership with E3D we’ve been lucky to get our hands on a unit to review and take it for a spin ourselves.
What is Revo?
If you’re familiar with FDM 3D printing, you’ll know your printer has a hotend. Plastic filament is pushed through the hotend and the hotend’s job is to melt it so that it can flow out of the printer nozzle. A crucial part of this is that there are no leaks. If there are gaps that the molten filament can squeeze through other than the nozzle, problems can arise. Not only does a monstrous plastic blob grow around your hotend from the leak, but clogs and under extrusion will probably manifest themselves too. A working printer will rarely end up with a random leak – they usually occur after the hotend is disassembled and reassembled.
What’s the most common reason to reassemble a hotend? To change nozzle, of course.
Changing nozzle on a conventional hotend is tedious. Not only do you have to ensure that the new nozzle is nice and tight (and risk stripping the soft aluminium threads), but you also have to do it whilst the hotend is hot to ensure a good seal. I’d be lying if I said I hadn’t been burned when changing a nozzle before.
Revo is different; no longer is the nozzle a separate part of the hotend. Simply unscrew the cold nozzle and screw a new one in finger tight. No heat and no wrenching.
E3D provide a handy guide on installing Revo. We fitted a Revo Micro to a poorly Prusa Mini. It was one of the very first Mini’s to be sold by Prusa, and we purchased it from its previous owner after a bit of a rough start with bed levelling and extrusion. The Bondtech extruder is a common fix for the extrusion issues on the early Minis, but it didn’t do it for us. Due to this, we had the perfect excuse to pick up a new Revo hotend!
E3D’s guide is great and clearly outlines the process of swapping out the stock hotend for Revo from start to finish – no complaints there. They quote an install time of 1 hour and 15 minutes, which we first felt was very generous, until one of the final steps. The install of the hotend itself took around 20 minutes, but when it came to tidying the install up and making the cables neat and tidy, I hit my first issue.
The Revo’s cabling is very short and E3D provide extension cables to ensure that you can reach your printer’s mainboard; the cables are lengthy enough and there’s plenty of slack. However, the cable joint where the extension plugs into the short cables are very difficult to manage. They are simply too bulky to fit neatly within the Mini’s existing cable trunking and it took a little bit of head-scratching to make it all fit inside. It still isn’t pretty and over doubled my install time while trying to get the cables to be as neat as possible. I think the Prusa Mini will be one of Revo Micro’s biggest customers, so a little more thought into how those cables are tidied up would be be a nice touch.
Otherwise, the install is quick and easy. Once installed there is a little calibration to do on the printer and you’re good to go. I didn’t PID tune my hotend and have had no issues.
Changing nozzles has benefits. Big bulky prints can be printed much faster with a big nozzle and prints with fine detail can look excellent with a small nozzle. With a conventional hotend I’m very reluctant to change nozzle because of the hassle and often don’t take proper advantage of this key 3D printing technique – with Revo it’s much easier. Furthermore, there’s no need to recalibrate the printer’s Z height because E3D invested a huge amount of effort into ensuring that all Revo nozzles have a near-identical length. Combined, a once ten-minute job now takes a fraction of the time. Top marks there. No risk of stripped hotend threads, burns, or build plate damage due to a Z being too low on a new nozzle. One small catch that I can look past is that the hotend cannot have any filament loaded when changing nozzles, though. If there is some loaded, the user needs to heat the hotend to remove it and then cool it down again before starting.
The hotend heater also has a negative temperature coefficient – another great feature. To you and I this simply means that the electrical resistance of the heater increases as it gets hotter, and in turn, the heater can’t continue to get hotter and hotter until a meltdown (and fire) occurs. This is one of printing’s biggest safety issues and E3D have had a good punt at solving it. Adding to this, the hotend cables are well secured and have an anti-snag piece – securing and stopping cables from being caught and ripped away – a big cause of meltdowns/thermal runaway. The heater is also powerful: I was impressed to see the hotend rise to temperature very quickly. On the other hand the printer’s bed still needs to warm up though, so it’s great for filament changes but has little impact when starting a print.
The Revo’s heating is slightly unique due to the heater encircling the printer nozzle – something I haven’t seen before. This does have some implications on the way hotend temperature is reported, but I’ll leave the technical detail to Stefan at CNC Kitchen. Stefan has an excellent review at a technical level that explains this particular problem here. From a user perspective though, I did not notice this.
Although fitting to a Prusa Mini is certainly not the only use for Revo, I couldn’t help but notice how much smaller Revo is than the stock hotend. The weight saving here will be great for print quality on the X axis.
For me Revo has two key benefits:
- Convenient nozzle changes
- Increased safety, particularly for children or printers that might get left unattended (which shouldn’t happen, but we’re all guilty of it!).
Unfortunately Revo does come in at a steeper price than what E3D is famous for – the super cost-effective yet high-performing E3D V6. The current RRP of the Revo is £69.90 + taxes with just one nozzle (having only one nozzle removes one of Revo’s biggest selling points…), or £109.80 + taxes with four nozzles. As you can probably infer, a big part of Revo’s cost is the nozzle. Just one standard nozzle comes in at £18.95 + taxes and that isn’t anything special. It isn’t hardened steel or Nozzle X, it’s just plain old brass.
The cost of nozzles is a major sticking point. Nozzles are consumable and it’s reasonable to assume that any long-term 3D printer will need plenty of them. The current price point is difficult to justify from a consumer’s perspective, but is understandable from E3D’s side. E3D nozzles are already known for their superior manufacturing quality, but Revo nozzles are much more demanding. Why?
- A single Revo nozzle is made of many parts of a conventional hotend. Where a hotend nozzle was literally just a nozzle, a Revo nozzle is both a nozzle and a heatbreak.
- As mentioned earlier, there should be no need to adjust Z-height between nozzle changes with Revo. This puts E3D up to the challenge of ensuring that all Revo nozzle units have a very, very tight tolerance on length.
On the whole, Revo is an impressive bit of kit. Our poorly Mini is for the first time whirring away and printing well. Revo is available in a few variants to ensure easy fitting to a variety of 3D printers and solves one of printing’s biggest pet peeves. Perhaps there are a few mild snags and it strays from what we’re used to within the community, but 3D printing is ultimately about creativity and that is exactly what E3D have used.
I am thoroughly impressed with the hotend but the ongoing cost of maintaining it will be an enormous blocker for many buyers. I’d recommend picking up the “fully loaded” hotend with four nozzles so that you can take full advantage of Revo’s nozzle swapping capabilities and pick up some nozzles at a slightly cheaper price.
HPI Tech is proud to offer a wide range of E3D’s new Revo hotends, available here through our official reseller partnership.