What knowledge do I need to designing hotends?

I want to design hotends but I don't know how to start with the design. I suppose that I'm going to need knowledge about thermodynamics, material enginering etc. But, What knowledge do I need exactly??

Thanks.

Edited 1 time(s). Last edit at 10/10/2016 08:24PM by Shockley.

You just mentioned the basic ones, but to be honest it's a lot of trial and error. You need to establish first what you want out of it (materials that will extrude, speeds that will print at and price you want to sell it for) then you will have to select the materials it's going to be built of based on qualities and price point, then you will have to design each part based on it's function and the esthetic you want to give it, the the experimentation comes and the iterations that will follow until you get the hotend you wanted in the beginning and hope the Chinese doesn't clone it.

My 0.02 cents worth - you need to know a lot about engineering, physics, and production methods.

The only reason the Chinese won't clone a design is if there is no profit in doing so. Trying to keep the Chinese away from a really good design is not exactly the spirit of Reprap anyhow.

You could design a really good hot end and never make a dime out of it.

You could design a really bad hot end (a more likely starting point) and work up from there.

What matters is, is the design buildable?

Quote
Shockley
But, What knowledge do I need exactly??

The knowledge to know what can be improved with current designs. From there on it's mostly try & error.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Hi Shockley, I agree with the previous post. Designing a hot-end is very much trial and error. The current hot-end design that's regularly used and you can buy for 3-4 USD.

Before they were there I made some extruders myself. Number 1, 2, 3 and 4 were total failures. Then I made a couple that worked reasonable # 4-7. Number 8,9,10 I was trying out to make improvements but they worked worse because there were new problems. Finally I was satisfied with the results of number 11 and 12.

Key problems with filament are friction and the melt point. You want to have a sharp transition (that's why the current hotness are having stainless steel - which is a bad conductor for heat and teflon in the transition) between molten and unmolten filament.
Since molten filament is like syrup leakage is another issue.

JDV