Well, my printer is down again, today. While (again) disassembled, looked at the assembly and went … hold on …
The upper end of the heat break is a chunk of aluminum(?) that clamps to the lower end of the finned chunk pictured.
Which means most of the finned assembly pictured is not doing much.
Right. Want to put this together, so I can continue printing parts for my next (vastly improved, perhaps) printer.
There’s still a lot of conduction of heat through the base plate of that heatsink. This is the makerbot-style of doing hot ends. It works, but just barely.
@ThantiK … well, yes, I agree with what you said … if a need to emphasize the dubious bit. 
The heat sink contact surface could be small at the hot side, but it must be a good contact then. I saw a huge difference after adding heat transfer compound paste used over computer CPUs.
If it’s the same system like on the older MakerBot printers I’d also suggest to add a thick piece of paper between the Aluminium Block and the motor. Usually these extruder motors are getting really hot. If the system is not design in a way that the motor needs this cooling it will also help to reduce the heat introduced into the filament.
yes and every time you need to lift the nozzle with a grub screw ou need to take the heatsink off too. but I just drilled a hole there for convenience, if your printer allows that try to add a heatsink on the motor, I had space behind the motor I just superglued it. it helps especially because I am running external fan that blows on the whole assembly plus part.
As a minor note, just turning the heat sink so the fins are vertical should make a difference. More metal to carry heat, and more airflow past the hottest parts.
@Preston_Bannister all true. Worth noting that aluminum has such high thermal conductivity and you’re shedding so little heat (a few watts at most) that you don’t need much cross-section of aluminum to get heat to the fins. The heatbreak / cooling bar interface and cooling bar / heatsink interfaces produce way more resistance to heat flux than the heatsink geometry.
Also important to note that heat-shedding optimization isn’t very important with PTFE-lined hot ends. It’s critical with all-metal hot ends. What happened here is that Makerbot made a pretty good all-metal hot end (mk7/mk8) that had very specific manufacturing and assembly requirements to ensure good heat shedding or it would jam. (So do E3D hot ends, btw.) Then when China started cloning Makerbots, they didn’t understand the “special sauce” and cut too many corners to decrease manufacturing cost. So the knock-off hot ends jammed with PLA and they quickly added PTFE liners to solve the jamming. A few more design iterations resulted in the mk10 used by a huge number of Chinese clone printers today. It works ok, but it’s optimized for manufacturing, not performance. A lot of design decisions were made by people who didn’t understand hot end physics.
That from a FolgerTech printer?
This is from a Wanhao Duplicator i3 Plus (rebranded as a Monoprice Maker Select Plus) - basically a Prusa i3 clone. The hot end is all metal. (Had it apart enough times.)
Meant to be my bootstrap printer.
Gotcha, same extruder that came on my FolgerTech prusa clone. Mine had a Teflon liner, worked great until the liner started to deteriorate. Eventually got an E3D v6.
@Preston_Bannister Wanhao Di3 definitely has a PTFE liner inside the heatbreak, unless they’ve changed very recently or you have the Micro Swiss upgrade for it.
The chunk of aluminum above the heat break has a metal throat. If there is a liner, I did not see it. Next time I have the thing apart, I will take a picture.
Bought mine in April, apparently from fresh stock, so it might have been manufactured earlier this year.
I have not done any upgrades to that printer as yet.
If that’s a makerbot . . . get your refund. NOW . . . they’re wastes of time and money.
I like the idea of turning the heat sink vertical. It would be interesting to see how much of a difference it really makes.
Also, I wonder if these “cross cut” heat sinks would have any measurable difference.
They should have more air flow and more surface area…
And no plastic spacers required.
@Preston_Bannister the liner is inside the heat break – you get to it by unscrewing the nozzle and heat break from the hot block.
Incidentally, there’s a side-effect to consider with the fin orientation… gotta consider where the fan wash is going. You may want or NOT want the airflow from the heatsink blowing downward. I find it helps ABS print quality a lot to have that tiny bit of warm air blowing by the hotblock, but you don’t want to cool down the hot block so much it struggles to maintain temp.
On my X-One printer, the heat sink fan is pulling air away from the heat sink. It is not blowing air onto the heat sink.
@Christopher_Bray that’s usually a assembly error. A lot of anecdotal evidence says it works better blowing on the heatsink. You can often make a Rep2 go from reliable to jamming just by flipping the fan around.
