Fitting the heater in the metal body

Hello,
I'm building my own "hot head" and have some doubts about the materials:
- I have a 12V 40W heater (stainless cartridge) and want to heat an aluminum block: how to fit in the metal? Need slack so that it can expand when heated? You have to use a substance (such as high temperature silicone) to facilitate the exchange of heat?
Thank You

Most of the ones I have seen are fixed in place with a set screw (see photo). Even high temp silicone is only good to around 320c to 340c max so I would not use them. Another method is to wrap the heater block with Kapton tape to hold it in place.

The heater cartridge gets plenty hot enough to heat the aluminum block without needing to worry about maximizing the surface area the is in contact with the block. If it would make you feel better you can prep the block with heart sink compound before inserting the cartridge.

Also, there is no concern about expansion of the cartridge within the block since they will both expand when heated.

You will need to pay attention to insulating the block once the heater cartridge and the thermistor are installed, to minimize the radiated heat from interfering with the rest of the components. Otherwise, you will find that the heat rises into the filament throat and can cause jams or noodling between the extruder and the throat.

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-David

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Quote
MindRealm
The heater cartridge gets plenty hot enough to heat the aluminum block without needing to worry about maximizing the surface area the is in contact with the block. If it would make you feel better you can prep the block with heart sink compound before inserting the cartridge.

Also, there is no concern about expansion of the cartridge within the block since they will both expand when heated.

You will need to pay attention to insulating the block once the heater cartridge and the thermistor are installed, to minimize the radiated heat from interfering with the rest of the components. Otherwise, you will find that the heat rises into the filament throat and can cause jams or noodling between the extruder and the throat.

Standard computer heat sink compound is not rated for temperatures anywhere near what the cartridge will reach.

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Thank you very much everyone for your answers.
Now I have much clearer ideas.
This is a great forum.

Edited 1 time(s). Last edit at 01/22/2015 12:57PM by paxkuali.