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Build: Assemble a Hexagon Standard Hot End

Assembling your new Hexagon hot end requires a few tools. The Hexagon kit should come with the required Allen keys and a small Hexagon wrench. You will also need a crescent wrench, a 7mm open-ended wrench and some space to work.

Don't have a Hexagon Hot End kit to assemble yet?

Hexagon Hot End Kit 3mm

Hexagon Hot End Kit 1.75mm

Optionally, you may want to purchase high temperature safe RTV silicone such as Permatex High Temperature RTV Silicone and Kapton Tape (Polyimide) - 3/8 inch. If you prefer not to use the silicone boot you must have either Kapton tape or High-Temperature Silicone RTV to assemble the hot end.

You may wish to use a threadlocker, however, be aware that this may affect the performance of your hot end by reducing some heat transfer. Use a quality and appropriately rated threadlocker.

Disassembled Hexagon: Groovemount, cold end, cooling fins, heat break, heat block, nozzle.
Left to right: Groovemount, cold end, cooling fins, heat break, heat block, nozzle.

Start by disassembling the hot end. The cold end with the cooling fins has a small threaded protrusion. This area is the heat break. Unscrew it from the heat block. The heat block has a small removable brass nozzle. When you receive your Hexagon kit these items should be only finger-tight and easy to disassemble. Your kit may arrive without these items assembled.

Removing the small grub screw.
Remove small grub screw

This step is optional, but recommended. On one side of the hexagon-shaped cold end there should be a small hole. Using the Allen key that was included with your kit remove the small grub screw inside. The Hexagon kit should include a socket head cap screw we will replace this grub screw with next.

Replacing the grub screw with the SHCS (socket head cap screw).
Replace with socket head cap

This step is optional, but recommended. Locate the socket head cap screw. You should have a matching Allen key included in the Hexagon kit that you can use to tighten this screw. Try not to over-tighten the screw, but make sure it is secure. You may wish to apply a thread locker to this screw.

Tightening the nozzle
Tighten nozzle with crescent wrench and 7mm wrench.

You will need a 7mm open-ended wrench (not included in the kit) to attach the nozzle to the heat block. Tighten the nozzle into the heat block. The heat break should not be inserted into the heat block. If desired, you may want to use nylon-lined channel locks or another tool. It is important to tighten the nozzle into the heat block. Keep in mind that brass and aluminum are soft metals - be careful not to overtighten. If you are applying more force than it requires to open a stubborn pickle jar you may be over-tightening the nozzle.

Optional, but recommended. If you used the socket head cap screw previously mentioned in an optional step then you may wish to back that screw out slightly. Using a crescent wrench on the cooling fins and the 7mm on the heat break, adjust the cooling fins so that they align in a preferred way and the socket head cap screw is out of sight. Re-tighten the socket head cap screw after you have re-positioned the cooling fins.

Tightening the heat break into the heat block.
Tighten heat break with included Hexagon 4.5mm wrench and crescent wrench.

Using the 4.5mm Hexagon wrench included with your kit tighten the heat break into the heat block. The heat break should snug up against the top of the nozzle inside of the heat block. Tighten the heat break into the heat block again being aware that the heat block is soft aluminum. Failure to tighten the heat break and nozzle into the heat block can cause jams.

Thermistor
Thermistor with nylon sleeves moved up

The thermistor is next. Be very careful not to bend the leads of the thermistor too much. Be very, very careful that the leads are not exposed when you have finished assembling the hot end. If the leads of the thermistor short against each other or against the heat block you will see strange, inaccurate readings from your printer. You may also experience jams and other unwanted behavior.

The thermistor leads are covered by insulation. Heat resistant nylon sleeves cover the insulators. You will want to gently pull the nylon sleeves back so that you can see the insulators during installation and ensure that they are not touching (shorted).

Adding the silicone boot and thermistor
Thermistor pushed through silicone boot. Heater cartridge being added.

Line up the holes of the silicone boot and cover the heat block with it. It should sit flat against the heat block. There are two small tabs that should sit flat against the top of the heat block.

Gently push the glass bead of the thermistor through the side of the silicone boot. You may wish to add RTV Silicone to secure the thermistor in place and aid in heat conductivity.

Check again that the insulators are pushed down to to the glass bead, that they are not touching each other and that they are not touching the heat block. Gently adjust the nylon insulators so that they are touching the silicone boot.

Slide the heat cartridge through the silicone boot and into the large hole.

Check again that the insulators on the thermistor are pushed down to to the glass bead, that they are not touching each other and that they are not touching the heat block. Gently adjust the nylon insulators so that they are touching the silicone boot.

If you do not have the silicone boot or prefer not to use the boot you may wish to use Kapton tape to secure the thermistor in place.

Adding the heater cartridge.
Thermistor and heater cartridge inserted

With the heater cartridge and thermistor in place you may want to tape or zip tie the cables. This can help to keep the thermistor and thermistor insulators in place during installation.

Tighten grub screw to secure heater cartridge.
Tighten grub screw to secure heater cartridge.

Use the Allen key and grub screw included in the Hexagon kit to secure the heater cartridge in the heat block. Do not overtighten.

Assembled hot end
Hot end assembled - secure cables and verify thermistor insulators are preventing thermistor from shorting.

Check again that the insulators on the thermistor are pushed down to to the glass bead, that they are not touching each other and that they are not touching the heat block. Gently adjust the nylon insulators so that they are touching the silicone boot.

Assembled hot end with groovemount plate.
Assembled hot end with groovemount plate

Complete! You can add the groovemount plate and mount your hot end! If you are using a bowden configuration there is a small M6 screw in the top of the hot end that can be removed. Use an appropriate M6 push-fit adapter.

Once installed into your 3D printer it is often a good idea to heat the hot end to a reasonable temperature (as low as 140C will do) and carefully re-tighten the nozzle using the same method used earlier. Be aware that the tool will now be hot and there is an increased risk of injury. Be safe!