Hot end insulator jbweld and microballoons

Well I am just starting the process of figuring out how to make a hot end. I didn't have any of the materials that everyone listed so I starting thinking about different ideas to accomplish the end. I see how the extruder feed or drive must be thermally separated from the extruder tip or the print media will melt before ever reaching the tip and be impossible to push. So to make a long story short I tried an experiment. The only epoxy I could find that was high temp, cheap and readily available was jbweld. It is listed as good to 600* F. On its own I don't think it would work well as it is impregnated with metal so it would be very conductive. But I also had some glass microballoons sitting around from another project. These are available at hobby supply stores to make very light weight fillers. Anyhow I mixed up some jbweld and mixed in about an equal amount of microballoons. In my testing I was using a hot glue gun that runs about 350*F. The test piece I made slid into the hot glue heater assembly about 1.5" so was well embedded into the main heating area. There was about 3/8" sticking out of the chamber. I was able to easily hold onto the part sticking out with bare hands. The jbweld stayed solid and could be easily slid out of the heat chamber and back in again indicateing that expansion should not be an issue. The jbweld should also be machinable and was super easy to make. I just used the silicone tube that was originally attached to the glue gun and packed it full of the epoxy, microballoon mixture. Jb weld is very slow to cure, 5 to 6 hour before handleing. I found that if I put the filled silicone tube in a toaster over at 250*F it super accellerated the cure time and the piece was solid in under 5 minutes. It was very easy to push the piece out of the silicone tube with no damage to the tube so it can be used over and over. Couldn't find anything on a search about this so I thought I would make my first post hope it is useful.

I tried JB Weld once and found that it wouldn't take the high temperatures very well. I then tried a material used for muffler sealant and got a short or open in the circuit which scrapped the entire hot end. Then went to resistors as a heating source for the hot end and gave up the glues forever. Save youself time and effort and skip the glue.

This would only be used as an isulator in place of the ptfe or peet pieces. I would still use a resistor as a heater. Last night I put the piece directly in the flame of the stove. It will burn if held direct in the flame for an extended time. If you just put very near the flame you can immediatly remove and grab the end.

My mistake your subject misled me to believe you were trying to find something to hold up to the high temperatures at the hot end. It should do fine above that but you realize that if its part of the structure it also must be structurally strong. Glues are normally used to bond two surfaces that are close to each other but I'm not to sure they are well suited to being cast in to a block or something. or have the strength to hang on to threads.