I literally have no hotter fuel as I have added these mods myself. So not part of a mod pack. The parts for vulcanite tools are in creative UI. But can't melt vulcanite with lava. An that's the hottest fuel I have.

you can use molten thermite as a hotter fuel

How? I have no clue how to get nor create it? I don't use "Not Enough items" and if it involves your crusher that's also impossible as the machine block refuses to be crafted.

yeah exactly, by the way I strongly suggest you to use Just Enough Items, it really helps with recipes. @Tigerdemigoddess
As I stated in #239 though I will add a new page to the wiki to explain the use of thermite a bit better
If anyone knows Markdown and wants to create a new page about it in the wiki they can do so because wiki editing is open to everyone

you get molten thermite in your tinkers smeltery, by smelting thermite in it. You can craft thermite, with potash, sulfur, and... something else, I forgot what it was, but i know that you can definitely obtain it... oh wait, you have the vanilla recipe book, you can just check for the third thing there.