Jump to content

Voron 2.4 - Rapido 2 UHF upgrade

Recommended Posts


Okay so it's not really a build thread but I thought I'd post up the things involved with a hotend upgrade - I was running a Revo Voron but decided to upgrade to a Rapido 2 UHF.

I found that I was having cooling problems with the Revo, I don't think it's down to the Revo alone, I think the ducting design had some role to play.

Dirk found the STLs "Posted February 22

Just had time to do a search for Rapido UHF v2. It shows me these:



I hope it helps." - thank you Dirk


I'll probably print the front again as there some cooling faults (it was printed with the Revo).

So now it was time to dial in the Rapido, I used the calibration steps in Orca for this.

First thing I had to change was the temp, the previous setting of 255 was too hot, 245 gave better results (sorry no photo).

The flowrate was pretty straight forward, I didn't change it.


The pressure advance is the first test where I started to see better results than what I could get with the Revo.

I dialed down to 0.75


I didn't bother with the retraction test, I have never had any string problems and still don't.

The Orca Tolerance test needed a 0.1 X-Y compensation before the hex key would go in the 0 option.


Then the fun started - the Max Flowrate.

I did lots of runs, and I mean lots of runs.


This one topped at 80


80-100 found the limit, so I settled on 70.

I haven't done the VFA test yet as I needed to print a few items to finish off the upgrade.

But before I could do that I needed to tune in the filament (Overture ABS).

I was trying to get rid of these small imperfections that I just could dial out with the Revo.



Everybody says "turn off the cooling when printing ABS", so I did and it wasn't good!


After a number of test runs with my own test tower.


I can now print parts like this - it's a 12.5mm hole in 17mm wide face that's 5mm thick.


The ringing test shows that there is some ringing but not much. If I ever find a how-to that I can understand I may tune that.




It took me the best part of a day to get it all dialed in to my satisfaction.

Thanks for reading.

I think it's stong enough for an egg...



Edited by Titus A Duxass
Duplicated photo.
  • Like 4
Link to comment
Share on other sites

@Titus A Duxass this is a great overview. Thank you for this very extensive dialing in of your new hotend.

This is the first time I read about something negative on the Revo Voron. Maybe one of our experienced Revo fans would like to comment on that? @mvdveer? @Penatr8tor @claudermilk


I have a few questions, if you can reference / link the tests you used (except the one model you made yourself), I could do them too. would be cool. (the hexagon head test is new to me).

And one thing I am surprised about, your flow rate is between 70-100 mm3/ second? That is about twice the amount as what I found with the tests from Stefan from CNCKitchen.  (and what is in SS profiles of Ellis). But it was a UHF 1.0, what I had, with CHT nozzle.


And the test with the towers, the numbers, it is percentages? So you have best results with 100% cooling on?
I have my cooling off for all plastics for the first 2-4 layers. After layer 4 to 10 I put it to 10%, as recommended by Nero3D (his video about printing abs for dummies). When I increase to 20 or 30%, I get problems with layer adhesion with my ABS.
But your examples demonstrate very good results. 

Thank you very much for taking the time to write it up. very nice to see these beautiful prints, requires 'some' tuning 🙂

  • Like 1
Link to comment
Share on other sites

Posted (edited)


I don't know if the Revo was at fault, my feeling is that the design of the ducting is more likely to blame.

All the calibration tests, including the tolerance/hex head test, came from within Orca Slicer, there are similar ones in SuperSlicer (which I also intend doing).

The tests with the towerrs - yes those numbers are the percentage of fan speed. There is very little difference to see at between 40-80%.

I've just printed out this egg cup.


It is rock solid, there are no issues with layer adhesion.

Here are my Orca Slicer cooling settings.


As you can see there is no cooling for the first 3 layers and then it jumps to 80%.

I will be reducing the fan speed to find the optimum, the big change for me was the speed for overhangs.






Edited by Titus A Duxass
Photo change
  • Like 2
Link to comment
Share on other sites

1 hour ago, Dirk said:

This is the first time I read about something negative on the Revo Voron. Maybe one of our experienced Revo fans would like to comment on that? @mvdveer? @Penatr8tor @claudermilk

Hahaha Sadly I don't have a Revo. I went from V6 to Dragon HF to Rapido and stayed with the Rapido so I can't comment on the Revo.

I can comment on the Rapido tho... And there's not really much to say but, you know me... I can be long winded, LOL. With the Rapido, I haven't really had a clog or failure. It heats up extremely fast, in casual testing, the heat up time was ~20 seconds from ambient to 240c, pretty impressive. I like the rubber boot, it's thick and robust and black so it doesn't discolor like the old orange Dragon ones. I like that it uses regular old V6 nozzles. I have a bunch of different ones I've tried from cheap brass ones to CHT to Diamondback. The nozzles are easy enough to swap out with a 3D printed torque driver, I don't even need to remove the rubber boot. Some people have complained that the ceramic heater / thermistor combo is not robust enough... maybe it isn't for the heavy-handed person but, I'm on the careful side and haven't experienced any of the breakage issues people complain about. Overall, I think it's a good hotend. 😎👍


  • Like 2
Link to comment
Share on other sites

16 minutes ago, Penatr8tor said:

Hahaha Sadly I don't have a Revo.

Hmm... Memory isn't what it used to be. Sorry for falsely accusing you.

The rapido costs a bit, but delivers and is very low maintenance (to me). 

I also like that it has components that you can buy for a few bucks and look familiar.

About the ceramic heater thermistor... The first time I tried to put mine in the stealthburner printhead, the wire that was soldered on ceramic head piece broke off. Nothing to do with heavy hands. It is a design flaw 🙂

I contacted the triangle lab guy on AliExpress and he sent me a replacement free of charge. Said it would be optimised for the Voron stealthburner in version 2. And they did.

but indeed with a bit of care it would not have happened 🙂 ( less pulling on the thermistor / heater cables when pushing the print head cover down)

  • Like 1
Link to comment
Share on other sites

2 minutes ago, Dirk said:

( less pulling on the thermistor / heater cables when pushing the print head cover down)

That frikken cover LOL. I hear ya on that. Stuffing the random collection of different connectors from my Formbot harness has been, how shall I say... Challenging to say the least Hahahaha.

I'm going toolhead PCB with umbilical on my 2.4 refurb. Check out my build diary if you haven't already.

  • Like 1
Link to comment
Share on other sites

9 hours ago, Dirk said:

Maybe one of our experienced Revo fans would like to comment on that? @mvdveer?

Running 10 printers on Revo's - never had an issue - but then I am not pushing speed. The VZBot has a first generation Rapido UHF - no issues either. Again - a matter of choice. Just like cars, motorbikes, fridges, TV's, etc. Some consumers may have problems with a specific brand, whilst others won't. Went with Revo because of choice and ease of use, nothing else.

  • Like 3
Link to comment
Share on other sites

53 minutes ago, mvdveer said:


Nice round number. also means 10 times more experience compared to someone with just 1 revo. Thanks for sharing.

If it would have been a structural problem, like their first version thermistor wiring, you would have known. That is why I asked. 

I was hoping you or anyone else would be able to recognize / diagnose the problem @Titus A Duxass was having with his Revo. So I think I will have to assume he was right and it had something to do with his "flow-duct" problem.

  • Like 1
Link to comment
Share on other sites

4 hours ago, Dirk said:

So I think I will have to assume he was right and it had something to do with his "flow-duct" problem.

Sounds like it yes. AS you indicated - way back when they were first released, I had a thermistor fail, but this was replaced without charge. (Sorry am a bit distracted at present)

  • Like 1
Link to comment
Share on other sites

I am running 3 Revos (one mostly sits, poor little Mini+) and they run well for me. I have a  couple of the early preorder units, one on the Mini+ and one on the Trident. I had the early production failures on the Trident one and got the heaters replaced without problem; then new one just works. Any problems--aside from early teething issue heaters--has been attributed to something other than the Revo.

I do push the capabilities with running my tiny nozzles (0.25 and 0.15), but running the 0.4 and 0.6 it just works.

I don't know what has been changed on that front piece, but I'd revert to a stock Stealthburner setup and see if that helps the Revo at all.

  • Like 2
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...