Crispy HotEnd

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Contents

A Bit of Background

This HotEnd was developed after struggling with the fact that in Argentina (were I live) PEEK is very hard to come by, very expensive and a controlled material (since it can be used to manufacture guns).

Therefore, I went and designed a PEEK-free HotEnd.

Since PTFE is available and fairly cheap, I started to work on building a HotEnd based on that insulation.

PTFE is easy to work with but the threads don't last long and are quite fragile. To solve this I went on and designed a "contained" PTFE insulation.

I took some ideas from the Budaschnozzle (which I tried, unsuccessfully, to build replacing PEEK with PTFE)

I'm a Hobbyist Lathe operator, so a lot is done on my lathe. That's a lot of help and makes this cheap.

I've used this HotEnd for at least 3 months now, and around 13 Kg of filament have gone through it. Normally I print with 0.5 mm nozzles at 40 mm/sec and at 230 - 245 ºC.

I Hope some people out there find it useful.

Gustavo "Crispy" Blanco

The Crispy HotEnd

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Watch it in action

The HotEnd Disassembled

Allparts.jpg

BOM (Build of Materials)

  • 1 * 50 mm Long 12mm Aluminium Round Bar (Barrel)
  • 1 * 20 mm Long 12mm Brass Hexagonal Bar (Nozzle)
  • 1 * 12 mm Long 12mm PTFE Round Bar (Inner Insulator)
  • 1 * 25 mm Long 1" or 25mm PTFE Round Bar (Outer Insulator)
  • 1 * 25 mm Long 1" or 25mm Aluminum Pipe (Shield)
  • 2 * M8 Large Washers
  • 2 * Pieces of MDF 5.5mm thick (use the large Washers as a template)
  • 1 * M8 Nut
  • 1 * 6mm x 32mm x 80mm Aluminium square bar
  • 3 * 1/8" x 50mm Bolts
  • 3 * 1/8" nuts
  • 2 * M5 grub screw

The Build

Tipically I start with the Barrel.

It's a 50mm long 12mm Aluminum round bar which it turn to 8mm in diameter for 45mm, and make those 45 mm a 8x1.25 Thread.

Bar.jpg

Next, I take a piece of 1" (or 25mm) Aluminum Pipe and cut a 25mm long section.
On the Lathe and with a piece o 25mm PTFE, turn it so you can fill the pipe (try to get it tight).
With a 6.75mm Drill bit, drill the PTFE (at least 30mm deep)

Then with a 12mm Drill bit, drill 18mm into the PTFE.
Tap the remainder of the 6.75mm hole (8x1.25 thread)

Now take the 12mm PTFE and brill a 3.2mm hole, drill it all the way.

You should end up with this.
PTFE Insulator.jpg

Now, insert the Barrel into the large PTFE section, using the largest hole, and screw it tight.
Bar-PTFE.jpg

Add the Shield.
Bar-PTFE-Shield.jpg

And the small PTFE to enclose the barrel.
Bar-PTFE-Shield-Conector.jpg

Complete the Mid Assembly by adding the parts in order.
To make these parts I've used the plans for the Budaschnozzle. Just drill the centerhole bigger (8mm)
Check that the holes are aligned.
Bottom Assembly.jpg Bottom mid.jpg

Now to Finish he Bottom Section, add the Heater Block and Nozzle
Notice the Heater Block has a 3mm hole drilled in the center for the thermistor. With heat block and nozzle.jpg Bottom done.jpg

The Top Needs to be finished as in the picture. The MDF spacer is similar to the one used befor, just drill the centerhole to 12mm. Top Assembly.jpg

To finish the assembly, add 2 resistors and 2 Y shaped Cables to connect the Resistors in parallel. HotEnd with Resistors abd Connectores.jpg

Crispy HotEnd v1.5

Updated 06/17/2013

After receiving a few suggestions in Argentina's RepRap Forum, I decided to take the time to make the following changes and all the tests show better performance.

First, replaced the film resistors with Ceramic Heater Cartridges.

Second, Drilled a 12mm hole, 7mm deep into the heater block. This allowed the Nozzle to screw into the block, keeping it closer, compact and reduced the total height of the Hot End in 7mm

Third, Drilled a 2mm through hole for the Thermistor.

P6170151 -1024x768-.JPG
The Crispy HotEnd v1.2 (notice the new Heater Block)

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Heater Block mounted (notice the hole for the nozzle)

P6170153 -1024x768-.JPG
Nozzle screwed in.

P6170161 -1024x768-.JPG
P6170163 -1024x768-.JPG
Heater Cartridge in place. To fit it snugly wrap it in aluminium foil (if required)
Hot End