@Chris_Brent They’re just 2 holes 16mm apart. Can’t say anything about matching a Kossel because I’ve never used one.
I posted these pics on another forum and this was the response. Quote"Those cooling fins look very inefficient." Which I agree with.
@Jeff_Dewe Care to share the link? I’m curious to learn why they would be inefficient. So far our tests have shown that they do their job.
sure Shai, you have to join first, but its a good group. https://www.facebook.com/groups/TEVO.3dprinter.owners/1005641716196469/?notif_t=like
@Jeff_Dewe and why would they be inefficient? The whole point of the design if to increases the radiating surface, which the fins do. Their thickness is not that relevant as the material is a good thermal conductor. (A reason why on processors you have pegs/columns and not fins anymore - this almost doubled the radiating surface). I’ve made my own extruder with 2mm gaps and 2mm fins. It’s perfect. This after I noticed that even a screw with spaced washers does the trick just fine.
So, again, why would this design be inefficient?
well if the fins were thinner, you could have 20-30% more fins, Also the thinner that material the quicker it cools, If put a hot cast iron pan in a sink of water. ? The steam goes up in the air and then you take it out of the water and starts to get hot again. Because the metal is thick and retaining heat longer. The outside cools the inside is still hot. I am 100% sure that thinner metal with a larger surface area will cool quicker than thicker metal and less surface area. Plus just an Idea, if the fins were angled down say 35-45’ so when you attach a fan to it, it also blow/directs some, probably not much down to the surface?
@Jeff_Dewe making the fins thinner would make for a more costly fabrication procedure. Adding 2-3 more fins wouldn’t do all that much, considering the mass of the entire thing. As there is a fan, you’ll always have cool air. This is in Al, so comparing it to cast iron is just silly as cast iron rather stores heat. Taking about angling the fins makes it clear you don’t know how turning works.
@Jeff_Dewe You don’t necessarily want the fins to be cool. What you want is maximum thermal transfer from the core to the environment, but if the fins are room-temperature, the air blowing over them won’t cool them any further. If, however, you are able to conduct enough heat away from the core that the fins and the core maintain nearly equal temperature, the fins will be warmer, but that means that they will have a greater temperature differential with the air being blown over them, and they will lose more heat to that air, thus making the temperature of the whole heatsink (including the core) drop. Of course, taking it to the opposite extreme, a solid block with no fins wouldn’t have much surface area, which also means a reduced rate of heat loss to the environment, so it’s a balancing act. You want a lot of surface area AND a lot of thermal conduction. Is this the ideal balance? Probably not (perfection being an infinitely small target), but it’s probably not as far off as you think. Combine that with the manufacturing difficulties presented by exceedingly thin fins, and this looks like a pretty good middle ground.
@Whosa_whatsis I should find a way to subscribe to all of your comments, wherever you post 
@Shai_Schechter this is the hot end I always wanted to make, but with the addition of a stainless steel cage (as in my old post http://www.tridimake.com/2014/03/thoughts-and-hints-around-hot-ends.html )… we are presently assessing hot ends, I need to buy one of these if you plan to mass market them 
Will you have 3mm and 1.75mm versions
We tried adding more fins by making them thinner and it did not improve anything. Only made it more difficult to machine and added cost.
Other than this… we also made them slightly thicker so that the heat is transferred to the outside tip of the fins. Because of the fact that the fan is flat against the heatsink instead of mounted on a shroud like an E3D, there is no cooling being done in the center of the fan, only where the fan’s fins make contact with the heatsink’s fins. Basically a sort of circular cooling “dead-zone” in the middle.
I think at the end of the day if a material prints fine without issues, then there’s nothing to complain about. With that said, any suggestions on what type of materials you guys want us to test to ease your worries?
@Whosa_whatsis that’s what I expected the response to be. I suppose I will need to try it out to see if it actually works as described. I’ve played around with smaller heater blocks on E3Ds - specifically with thermocouples much closer to the heater cartridge - and haven’t had the best results.
Also, if needed, one thing that could be done to increase the surface area without adding machine time or thinning the fins would be to tumble them or bead blast to rough the surface up.
@Taylor_Landry Actually, just anodizing aluminum heatsinks apparently has a not-insignificant effect on their efficiency, probably mostly for that reason.
Yet to see an aerogel insulated hot-end… But interesting conversation anyway.
Looking forward to the pre-order. This would be a great little hotend to retrofit water cooling to. That’s what I will likely do. I’ve converted all but 1 of my E3D hotends to watercooling. I print PLA almost exclusively on 5 machines for over 20hrs of printing (combined) a day and I have not had a single PLA jam in well over a year since I converted. In addition to a more compact hotend, there is just something magical about water cooling for PLA extrusion - I hypothesize that the very short melt transition zone is the reason but haven’t explicitly tested this. Thermal imagery would be interesting on a watercooled version.
Our new Mini Hotend is now available for pre-order! Reserve yours today and get a $10 discount. Link: http://deltaprintr.com/shop/parts-and-accessories/hardware/mini-hotend/
yay! got two of them…
and one goes to Portugal…
Is there a peek insulation inside or just good ol fashion all metal? I need to print nylon (a lot) and it goes without saying that it needs to be all metal (bunch of other fumes at 260)
@Shai_Schechter more surface area means more cooling effect, maybe sandblasted? Anyways I am considering to order your hotend for nylon printing