Two types of 3D printer owners

[Dave_Sohlstrom]

I've been working on my new hot end. I have some new nozzles that are in USPS never never land. Here are some photos of the work so far. The wire you see coming off the bottom is a thermocouple that will be used if I ever get the dual temp controller I ordered. There is a hole for a thermister and a thermocouple temp probe on the other side. Bottom piece is 1/2" copper bus bar with a brass adapter silver soldered on.

[img]http://i132.photobucket.com/albums/q3/D ... 0_0311.jpg[/img]

[img]http://i132.photobucket.com/albums/q3/D ... 0_0312.jpg[/img]

[img]http://i132.photobucket.com/albums/q3/D ... 0_0313.jpg[/img]

[mhackney]

Looks great Dave. Looking forward to seeing how it works!

Cheers,
Michael

[michaellatif]

Looks nice Dave! I like the copper and brass colors, I bet the copper will change color with time and usage.

[Leeway]

That does look good. I am trying to design one myself just to save a bit of cash on what seems to be a fairly simple part. I ordered some small brass air and gas fittings and some thin and thick wall nipples to try to come up with something. I also have some of the plastic PTFE insert tube.

Let me ask you why you went with Peek for the top part rather than brass, aluminum or copper?
Most of the hot ends I have seen use that there and I suspect it might be for heat dissipation. Just guessing of course, but I know you would not want high heat translated up to the mount because most of those are printed plastic as well.

I am hoping that with an aluminum mount for the hotend, that may dissipate the heat well enough not to melt the extruder. I haven't had time to do any of the work yet. Did buy some tiny drill bits. My first task is to determine how to hold those secure in my lathe.

[Dave_Sohlstrom]

I have noted that the plastic mounting plate already has some signs of heat. I tried to think of a way to change out the PEEK but I was unable to figure a way to keep the heat away from the plastic parts so just went with Steve's design. I do have threaded holes available that I can attach a heat shield to so even less heat goes up.

[michaellatif]

PEEK is mainly used as an insulator in this scenario. It helps limit the amount of heat transferred from the extruder to the mounts and rest of the carriage.

[Dave_Sohlstrom]

Mike I agree. I could not think of a material that would do a better job so I kept the PEEK. Who in the group knows the temp that PEEK starts to soften and melt. I do know it melts real well at 650F.

[Leeway]

Thanks for confirming what I suspected, guys. Here is the Peek WIKI.
http://en.wikipedia.org/wiki/PEEK

It has the temp range there.

So the biggest issue for me will be heat dissipation at the hot end mounting point. I'll get to thinking on that one. Look forward to seeing your results, Dave.

[Dave_Sohlstrom]

interesting the wiki says it melts at 662F so I guess my temp probe reading around 650 was close. Kind of hard to tell with the panic of getting it shut down.

[mhackney]

Like most polymers, PEEK does not have a discrete melting point. Many factors influence the polymer when it is synthesized that have an effect on MP. A ceramic material might be a good option. There are millable ceramics that do not melt and are good thermal insulators. I haven't investigated them for awhile but it might be worth looking in to.

cheers,
Michael

[@CiDG]

That really stinks, Dave. I really like the new hot end you're building!

The second time I powered up my printer, I stepped out of the room to do something and I smelled something hot. I ran back in and while it hadn't melted or gotten distressed, there wasn't any good reason for it to have gotten so hot. I shut down and turned my thermostat down as far as possible (just a few degrees rotation, as I am running a 10 Ohm resistor). I powered up again and I have never had a problem again. I am concerned the velleman may not be the best setup for regulating temp without some sort of overheat alarm or an emergency shutoff relay.

[Leeway]

Here is another interesting link or Wiki about DIY hot ends if you haven't seen it. Some interesting info there.

http://reprap.org/wiki/DIY_Direct_hot_end