RescoHotEnd
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Contents
Intro
When you have extruder problem, one of the most scaring doubt is: "it's something related to plastics parts?". Usually extruder use PTFE or PEEK as insulator and/or sleeve and this parts and soften or melt. This limit the extruder maximum temperature. So I want a full metal extruder and I made one.
Pro
- All metal parts
- Easy to assembly (only three parts, no glue)
- Really solid assembly
- Aluminium block heated by glass resistor
- Interchangeble nozzle
- Simple mounting plate (compatible with mendels parts mount)
Cons
- Forced convection is needed to cool down the cold-end
- In theory greater friction due the miss of PTFE sleeve can limit print speed. In practise I can print on my RepRap Prusa i2 0.4mm layer height of ABS at 60mm/s without problems. Print speed is a value determined by to many parameters, I have yet to find a good measure of this aspect
Parts
Nozzle
The nozzle is made of brass.
Coldend
The coldend is made of stainless steel, in order to minimize heat transfer. The fins act as heat sink, while the material between them is thin as possible to increase heat resistance.
Heater block
The heater block is made of aluminium and houses a 5mm diameter glass resistor and a axial thermistor. We use a 100K 1% resistor (104JG1FRA), the temperature table (taken using the less precision method you can image) is:
#define NUMTEMPS_3 62
short temptable_3[NUMTEMPS_3][2] = {
{1,846},
{32,295},
{34,290},
{37,285},
{39,280},
{42,275},
{45,270},
{48,265},
{51,260},
{55,255},
{60,250},
{64,245},
{69,240},
{74,235},
{80,230},
{87,225},
{94,220},
{101,215},
{110,210},
{119,205},
{129,200},
{140,195},
{152,190},
{165,185},
{180,180},
{196,175},
{213,170},
{231,165},
{252,160},
{273,155},
{297,150},
{322,145},
{349,140},
{377,135},
{407,130},
{439,125},
{472,120},
{506,115},
{541,110},
{577,105},
{612,100},
{648,95},
{683,90},
{718,85},
{751,80},
{782,75},
{812,70},
{840,65},
{865,60},
{888,55},
{908,50},
{926,45},
{942,40},
{956,35},
{968,30},
{978,25},
{987,20},
{994,15},
{1000,10},
{1005,5},
{1009,0},
{1018,-20}
};
Mounting plate
The plate is made of iron, you can use every type of metal stiff enough.
Assembly
The following is a link to a Youtube video of the extruder assembly. The part relative to the hot-end start at 1:10
Drawings
| Part | Link |
|---|---|
| Cold-end | http://www.resco-research.com/downloads/ColdEnd.pdf |
| Nozzle | http://www.resco-research.com/downloads/Nozzle.pdf |
| Heater block | http://www.resco-research.com/downloads/HeaterBlock.pdf |
| Plate | Work in progress |
