SoliForum - 3D Printing Community — interesting issue i have with E3D type of hot end

Re: interesting issue i have with E3D type of hot end

2014-04-25T09:03:30Z

This sounds like you are turning off your printer while the hotend is still hot, which means the heater-block/nozzle etc will be still hot but the fan will be turned off. What happens is then heat creeps upwards unchecked and melts/adheres to the upper regions of the hotend.

Adding a bigger fan won't help, you just need to let your hotend cool down a bit while the fan is turned on before switching off the printer.

Re: interesting issue i have with E3D type of hot end

2014-04-24T03:30:44Z

elmoret wrote:

You're still going to get reduced airflow doing that, as the high pressure zone will sit on the edge of the blade until the blade is outside of the shroud, then it dumps pressure until it comes around to the shroud again. I would expect significant drop in efficiency over a similarly rated 30mm fan.
If you're set on the 50mm fan, at least print an appropriate duct.

I will print a better duct once i get my SD3 working...

I am not giving up on E3D; i installed it as a fix of my broken SD3 and clearly it did not go well since i was not prepared.

Just for fun, here are my upgrade plans:
1. Bought new SD3 hotend today; will restore SD3 to factory config and then will print MK5 with built in fan shroud for E3D.
2. Will install E3D with custom MK5 described above
3. Will upgrade to TC from thermistor.

I also got all metal hotend + extruder from ebay; that is scheduled to be delivered in May. I might stick it on SD3, but was originally planning to use it on my own build, which is going very very slow...

Re: interesting issue i have with E3D type of hot end

2014-04-24T03:03:39Z

You're still going to get reduced airflow doing that, as the high pressure zone will sit on the edge of the blade until the blade is outside of the shroud, then it dumps pressure until it comes around to the shroud again. I would expect significant drop in efficiency over a similarly rated 30mm fan.

If you're set on the 50mm fan, at least print an appropriate duct.

Re: interesting issue i have with E3D type of hot end

2014-04-24T02:44:42Z

elmoret wrote:

a 50mm fan on a 30mm duct will flow almost no air through the ducted area, for two reasons:
1.) larger hub size on a 50mm fan, which dominates the majority of the ducted area
2.) air flow will follow path of least resistance, meaning it will flow on the outside of the duct

Of-course you are right; however i did not center the fan for those exact reasons, 2 edges of the fan are aligned to the edges of the shroud.

Re: interesting issue i have with E3D type of hot end

2014-04-24T02:36:50Z

a 50mm fan on a 30mm duct will flow almost no air through the ducted area, for two reasons:

1.) larger hub size on a 50mm fan, which dominates the majority of the ducted area
2.) air flow will follow path of least resistance, meaning it will flow on the outside of the duct

Re: interesting issue i have with E3D type of hot end

2014-04-24T02:22:57Z

elmoret wrote:

No, your fan is too inefficient, and is letting the heatsink get significantly above ambient. That or your fan duct (do you have one?) is not efficient.
No one else has encountered this because people that break parts typically replace them with OEM parts, not what they had laying around.

Yeah, you are probably right. I am using OEM fan duct but the fan is not OEM.

I am pretty sure that, when properly used, the hot end works just fine. The reason for documenting my failures is to have a pool of issues/solutions for others who might make the same mistakes as me.

Re: interesting issue i have with E3D type of hot end

2014-04-24T02:11:29Z

No, your fan is too inefficient, and is letting the heatsink get significantly above ambient. That or your fan duct (do you have one?) is not efficient.

Not many folks have encountered this because people that break parts typically replace them with OEM parts, not what they had laying around.

interesting issue i have with E3D type of hot end

2014-04-24T01:40:30Z

Right off the bet i should say that i do not think this would be limited to E3D exclusively, rather all hot ends of that design.

The issue i encountered is that if i leave fillament in the hot end after turning the printer off, then it solidifies and so no new fillament can be fed, because the top part of the hot end does not get hot enough to remelt the fillament. I basically have to take the hot end apart and drill out the fillament from inside the tube.

Has any one encountered this issue before? Since i broke by stock fan, i am using a larger 50mm fan from ddr3 memory heat-sink. May be my fan is just too efficient?

I did not have this issue on stock sd3 hot end, since it has no heatsink. As the result i became a spoiled brat and now have a habit of leaving fillament in my print head.