Arcol.hu Hot-End v3.0 assembly manual

This page describes v3.0 assembly instructions, for the updated v3.0.1 instructions please read here.

Estimated Build Time: under one hour

Tools You'll Need

  • 2.5mm hex key
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  • soldering iron
  • xacto knife or sharp knife
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  • Kapton tape or tape
  • crimping tool
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  • wire stripper
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Parts you'll need

The kit should contain everything you need.

Fire cement are included in the package.
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This is the heater block:
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The thermistor:
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Another view:
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And the connecting wires:
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Before assembly

Before you start assembly please clean the aluminium nozzle carefully with dish soap. Make sure the barrel is clear and empty before assembly.

Look down the barrel against a light source to make sure there is nothing left inside. Any aluminium chips left from manufacturing can block the nozzle:
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Assembly steps

Preparing the thermistor wire (purple wire)

Step 1:
Strip about 4cm of the connecting wire.
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Step 2:
Twist the strands of the wire together. Make sure no loose strands are sticking out.
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Step 3:
Repeat for another piece of wire.
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Find the two metal crimp sleeves and the two insulating sleeves shown in the image. These will insulate the legs of the thermistor.
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Carefully spread the legs of the thermistor apart.
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The thermistor is really fragile, its legs are thinner then a hairline, you can easily break the leg of the thermistor. (tip: buy a spare one. It costs next to nothing, compared to the frustration it may cause!)

Slide one of the metal crimp sleeves onto the stripped length of wire, thinner end first:
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Make sure to orient the sleeve properly. The side with the flanged opening goes onto the wire last.
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Align the thermistor lead with the wire.
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And twist them together.
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Slide the crimp sleeve up to the middle of the twisted lead.
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Use the 0.5mm setting on the crimping tool
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And crimp the wires together
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Trim the thermistor lead on the other side of the crimp so it does not stick out.
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During cutting:
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After cutting:
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And repeat for the other leg of the thermistor.
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Power resistor

It's easiest to install the power resistor before you mount the thermistor.

Strip about 4cm of the thick heater wires.
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Twist each one together with the legs of the power resistor.
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Trim the excess wire so no wires stick out.
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This is how it should look once you're done.
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Remove the plastic side of the larger crimp sleeves. Use pliers or side cutters to grip the plastic while pulling the metal at an angle.
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The plastic should come off cleanly.
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Slide the sleeved along the wire onto the twisted power resistor leads.
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Crimp the crimp sleeves.
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Repeat for the other resistor lead.

Mounting the power resistor

The power resistor is thicker in some parts than in others. Its diameter varies along its length, and different resistors may also have different thickness. For more information about the internals of power resistors, please see this blogpost:
http://blog.arcol.hu/?p=1718

If the power resistor does not fit snugly inside the heater block (ie. if it can move around in its channel), you should pad it with kitchen foil (aluminium foil).

Take the previously prepared power resistor and the heater block:
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Prepare some aluminium foil to wrap the power resistor if necessary:
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Cut it to size:
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Wrap the foil around the resistor and push the assembly into the aluminium block:
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Once it is pushed into the aluminium block, cut off any surplus foil. To avoid short circuits, make sure it it cut flush with the channel.
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Mounting the thermistor

This is the most complex part of the whole build. If you generally just skim instructions, read at least this part carefully.

The thermistor is very fragile, so handle it with caution.

Open a satchel of fire cement at one corner with scissors:
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Screw the nozzle into the aluminium heater block, and cover the nozzle with Kapton tape, masking tape or anything else:
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This will ensure that the nozzle itself does not get any fire cement stuck to it. That way you can disassemble it later, when you want to clean the extruder or change the nozzle (eg: from 0.5mm to 0.35mm). Cover the top of the nozzle too, to avoid getting any fire cement into the nozzle. Remember that the nozzle has a really tiny opening, and any contamination can block it.

Take a piece of A4 paper and fold it into 8 layers total:
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That makes sure you have some clearence between the nozzle and the firecement.
Here is it prepared:
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If you are building more hot-ends at once, the best preparing them for firecementing:
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Take the previously assembled thermistor with wires:
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Put fire cement on the aluminium heater, and push the thermistor into the small hole in the heater block. Be careful not to let the leads of the thermistor touch each other or make contact with the heater block.
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Now you have two possibilities. You can either let the fire cement dry by itself at room temperature for 24 hours or more. OR you can heat it up using the power resistor and 12V power source.
If you choose the second option, the fire cement dries within 5 minutes. But do it carefully, because if you overheat it (>280C), you can kill the thermistor.

Until the fire cement has completely dried, the readings from the thermistor will be wrong. It may display 140-160C at room temperature. Once the nozzle has been heated up to 240C, the thermistor will report correct temperatures, as the fire cement will be completely dry.

Here is the heating setup:
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Any 12V power source will do, polarity is not important.

Heating in progress:
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Here are two nozzles done:
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Remove the (Kapton) tape:
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Building the extruder

Here are the things left to mount:
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Attach the stainless steel triangle and the heat insulation disk together with three spacers and nuts:
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Here is another view:
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Screw the PEEK insulator into the nozzle as firmly as possible. You can use two pairs of pliers too. This is important because the PEEK insulator must form a seal to prevent plastic leaking out.
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Take the sleeves for the thermistor and slide them onto the thermistor's wires:
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Repeat wit the sleeves for the power resistor wires:
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Thread the wires through the appropriate holes in the heat insulation disk:
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Bend each heater wire into an S-shape. It helps to secure the nozzle, and also prevents heat going upward:
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Take the copper pipe cap:
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Put the PTFE tube into the PEEK insulator, and put the copper cap on it:
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Slide the aluminium tube onto the PTFE:
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Put the two bottom mdf disks on. You should insert the M5 bolts into the disks at this point. The bolts are trapped in the hot end so that they cannot be lost.
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Stack on the remaining two MDF disks, and attach them with the 3 M3 bolts.
((Todo: Some images missing here.))

Bend the wires into an S-shape through the disks. This prevents the thermistor wires from accidentally breaking.
(please note that this picture displays 3 disks. You should have 4 in the kit. Depending on your printer's z-axis, you should use either 3 or 4 disks. )
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((TODO: replace the image with the final 4 disk version)

Cut all 4 wires to the same length:
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Strip the end of all wires:
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Wet the tips of the wires with solder:
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Remove any solder blobs from the ends of the wires.

Wet the molex connector's pins with solder:
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Slide a short length of heat shrink tubing onto each wire, and solder the wires to the molex connectors.
With a match or other heat source, heat the heat shrink tubing to finish the hot-end.
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Here is the final hot-end:
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Improvements

You can improve the heatsink by using a dremel. This way you can increase the heatsink surface, and also help the air flow around the aluminium tube:
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