I’ve been working on a dual bowden extruder design for my Robo 3d printer for a few weeks now and I’m looking to get feedback on the design.
It’s a fairly basic and contained design. The E3D nozzles mount to a plate with a V saddle insert. This secures the heat sink extremely well, requiring a large amount of force to twist slightly. The mounting plate then connects to the carriage via a screw acting as a post. This is them able to be adjusted height wise to calibrate the nozzle heights, with a spring providing resistance.
I’ve got most of the parts ready except for half the cold end. I have some concerns that I’d like feedback on if possible.
The use of 2 leveling inputs gives me concerns about the nozzle being slightly off angle. I’m thinking using a caliper to mesure the height off the plate would allow for verifying the plate is level, but still leaves margin for error. A single calibration point per side would be ideal but haven’t been able to come up with one.
Would the stock E3D fan provide enough airflow to cool 2 heatsinks? My instinct tells me the fan is very oversized for the the heat transfer load, but not knowing the specs of the fan I can’t verify for sure.
Is there any danger of blowing cool air on the nozzle? I’m trying to aim my part fan away from it but it’s been difficult to completely miss it.
Any ideas for a simpler belt tensioner?
My cold end choice has so far been the EZstruder due to the cost. I’m considering adding a geared stepper motor instead of just a stepper motor to give more control. Anyone with experience doing bowden with an EZStruder?
Any other critiques or criticisms are appreciated. Hoping to have it finished by next month.
Yes, i believe the limiting factor is the heat transfer through the heatsink and not the airflow around it.
The stock shroud has no shaped outlet and doesn’t affect the heater block negatively. I think your design should even outperform the stock one.
Have a look at how the Mendel90 does it on the carriage. Simple. effective and easy to implement.
The way you mount the hotends seems to allow them to swing about the Y-axis. If you turn them 90° about Z, that possibility for wobble should be eliminated.
Pretty much everything @Thomas_Sanladerer said. Also, you may want to look at the work that @Stefano_Pavanello has done with his badprinter2 as it uses 2 E3D hot ends, including a dual fan mount.
I would make the belt tensioner part removable so you can print the carriage inverted without supports.
Very clever design and awesome renderings yes, on the prototype of the BadPrinter2 we are using two E3D hotends with dual fan duct, but this dos not allow a good leveling of each head individually. In the series BadPrinter2 We arrive at a similar conclusion as your design and we think also to put a single 30mm fan to blow in the middle of the two heatsinks. I ask to @Sanjay_Mortimer the same question and he confirms me that it should work, better using a sort of splitter to divide the airflow and direct it through the two heatsink.
As soon as we build the first pre-series machine I can confirm you if this work, so keep in touch.
Keep on with your good work.
You’re quite right about the heat transfer and the fan. The main issues we see from people wrt cooling is due either to badly positioned airflow. Usually airflow too high up, which then causes a lack of cooling on the critical lower fins, then jamming occurs. The other common cooling issue is people restricting the space in which air can enter/exit the duct.
Your design looks perfectly good from a cooling standpoint.
@Thomas_Sanladerer I think when he is asking about blowing cool air on the nozzle in point 3, he is referring to the part fan, not the heatsink fan. I would say that obviously you want to minimise air over the heated parts, but a lick of air over the nozzle is really no disaster at all.
@Mike_Kelly_Mike_Make Out of interest, what was your reasoning for going with 2x E3Dv5 Bowdens over the Kraken? (Which has integral nozzle levelling, with no tilt issues.)
I fully realise that there are plenty of reasons not to go Kraken, I just want to understand what that reason is in your specific case. Market research and all that!
@Thomas_Sanladerer Thanks for all the suggestions. I definitely like the belt tensioner on the mendel 90 and will have to integrate that in some way.
@Tim_Rastall I’ll definitely check it out. I don’t think it’s possible to print without supports since each face has a raised feature. It’s not a big deal imo but that would have been a nice inclusion to the design…
@Stefano_Pavanello I look forward to hearing your results. Hopefully it comes out well. I’ll definitely be looking at your design in more detail.
@3roomlab This was modeled and rendered in Solidworks
@Tim_Rastall I modeled it myself based on the dimensions from E3D online. I tried searching around for a premade one but couldn’t find it.
@Sanjay_Mortimer Thanks for the confirmation about the design and the cooling fan. I’m curious if it is possible to include both fans but it’s nice to know one will work.
I actually spent a lot of time debating on the kraken and it came down to a few key reasons.
Cost: I’m trying not to turn my printer into a huge expense immediately. Getting the kraken would have been significantly costlier to go for than my dual design.
I’m already running a direct feed E3D, so to make it dual I just had to buy a second E3D with bowden coupling and a spare bowden heat sink. Only ~$115usd
Timeline. Initially my goal was to complete the dual mod in January but the timeline has been pushed back to february. I still need to purchase the parts for my 2nd cold end which will have to wait till the end of the month/beginning of next.
Models: I was planning on designing a kraken carriage but I wasn’t readily able to find a drawing or cad model of the kraken design. If this is out there and you could point me towards it I would appreciate it.
Hardware/software support: I know this is a matter of time before the electronics boards and firmware support arrive. I realize there’s no requirement to use all 4 nozzles initially and I could have just run dual till the support was enabled. But then we go back to point 1 on the cost concerns.
The kraken isn’t out of the question. Just a project for the future
yes, on the prototype of the BadPrinter2 we are using two E3D hotends with dual fan duct, but this dos not allow a good leveling of each head individually. In the series BadPrinter2 We arrive at a similar conclusion as your design and we think also to put a single 30mm fan to blow in the middle of the two heatsinks. I ask to