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Merlin Hotend & i3, who uses it?

Posted by Srek 
Merlin Hotend & i3, who uses it?
January 28, 2017 08:53AM
Hi all,
i am currently designing a new extruder that uses compressed air to cool the hotend. It would be pretty easy to also make it available for i3 printers.
It only works with a Merlin hotend and requires a aquarium membrane airpump for the compressed air, you also need a silicon sheeth for the heaterblock.
On the plus side the extruder is lightweight and you can use the Merlin with up to 260°C with this cooling. It is also pretty good for flexible material, printspeeds up to 90mm/s are no problem.
So if you use a Merlin with an i3 and you are interested, please tell me.
Cheers
Björn

Edit: You can see a prototype of the extruder in action here [b.bonkers.de]

Edited 1 time(s). Last edit at 01/28/2017 08:57AM by Srek.


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Merlin Hotend & i3, who uses it?
January 28, 2017 11:40AM
Oh, that's very cool. I hadn't really thought about how small you'd managed to make heat-break cooling area in your hotends, but now you point it out that looks excellent. Very nice work!
Re: Merlin Hotend & i3, who uses it?
January 28, 2017 11:53AM
Quote
JamesK
Oh, that's very cool. I hadn't really thought about how small you'd managed to make heat-break cooling area in your hotends, but now you point it out that looks excellent. Very nice work!
At HackFFM we discussed this years ago, but at that time we had way to complicated ideas on how to implement this. It turned out it is rather simple.
I have yet to push the hotend to see what extrusion temperatures i can reach before it breaks down. I just don't have any material here that needs more than 260°C to print.


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Merlin Hotend & i3, who uses it?
January 28, 2017 01:39PM
Here is a print with the extruder and experimental compressed air partcooling.
It is much more compact and lighter than any fan setup i know of.
[www.youtube.com]


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Merlin Hotend & i3, who uses it?
January 28, 2017 02:46PM
That's really nice. As well as being ultra-compact it should also be very robust. I've been going through small fans quite fast and it's getting really frustrating. The bearings go, possibly as a result of the g-forces when the nozzle hits any curled up edges while the fans are running. Given I have four fans on the (dual extruder) carriage it would be great to get rid of them all.

Edit: Ok, one thing I don't understand with compressed air part cooling - is the speed still controllable by the printer, or is it just on/off?

Edited 1 time(s). Last edit at 01/28/2017 02:48PM by JamesK.
Re: Merlin Hotend & i3, who uses it?
January 28, 2017 03:15PM
Currently it is not controlled at all, howver i already ordered solenoids for on/off switching. For volume control i want to add an adjustable valve, but that will need manual action. Maybe at some point i might switch this to a servo.


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Merlin Hotend & i3, who uses it?
January 28, 2017 03:24PM
This looks very interesting! Is it quieter than a fan? My memory of these little aquarium pumps is they are a bit loud. Or is it a case of investing in a good quiet pump?

Also, does the air get ducted out again, or does it just blow over some cooling fins? Does it need cooling fins, or can you just blow against a barrel? If it can, this may also make for a nice retrofit to an e3d v6 without needing the cooling fins.

Lots of questions, would be cool to see some drawings
Re: Merlin Hotend & i3, who uses it?
January 28, 2017 03:55PM
The pump is not noiseless, but it only mitts a low hum that i can easily ignore. It is much less unnerving than those small fans.
The pump will cost more than a fan, but they are designed to run 24/7 for years.
To use compressed air with most hotends you would need a new cooler. The current ones are all designed with fans in mind. The Merlin is pretty unique in that it has a very small area for cooling and does not use cooling fins.


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Merlin Hotend & i3, who uses it?
January 31, 2017 02:41PM
Current state, this is still beta, but works reliably.
Cooling with compressed air




[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Merlin Hotend & i3, who uses it?
February 01, 2017 01:09PM
That is really neat, you can hear from the hissing that plenty of air is getting to its target. I am considering doing much the same on my present build but am constrained to using brass for the part cooler - at least until I figure out how to print in PEEK.

Mike
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