What to use for hot end insulation?

Hello All

I am thinking there are numerous ways to narrow down the wild (up to 10 degrees) temperature oscilation of my extruder around the target temperature.

1) I can examine the trend of the temperature and switch the heater on (off) even if it is over (under) temp but is consistently decreasing (increasing) and within a specified range of the target temp (say 1.5 degrees - to be fine tuned).

2) Add thermal past between the threads of my nozzel and heater block and barrel.

3) Wrap the hot end in an insulator.

It is point three I would like to get some pointers on what would be good and easy to source and easy to work materials for this insulation.

Would the standard loft insulation be OK or would the high temperature (up to 300 degrees C) be too hot for that stuff?

Any other materials?

Cheers for any advice

I don't think insulation will make it any more stable. It just helps if you are struggling to reach the required temp and reduces the heat rising into the extruder base and carriage.

Yes loft insulation has been used.

What sort of heater are you using. If it has low thermal mass then it will need PID and that needs to be tuned correctly or it may swing wildly or never reach the target.

If it has high thermal mass you can use bang-bang control as long as the thermistor is well coupled to the heater.

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Hi Nop

I have a heater block so I guess that is high thermal mass...

I have changed the code to do bang-bang... but the temperature still swings wildly. Hence maybe switching on the heater if the temp is over but the trend is down and approaching the target. Bit like putting the breaks on the temp change..

I do imagine insulation should help the swings in preventing heat loss from occuring too rapidly, given the ambient temperature is around 18 degrees.

I have got some cheap thermal paste off ebay so that should improve my temperature readings...

There is loads of loft insulation sitting in the shed so I will use some of that and see what happens.

We use loft insulation (mineral-wool) and it works very well. Some types can take about 1000°C/1832°F

I have not yet tried, but the specs look good for using high temperature silicone for insulation. I bought an oven mitt made from blue silicone. It is supposed to be good enough to dunk your hand in boiling oil. I cut multiple disks and punched out the center hole so that when the time comes, I can slide the disks over the hot end and secure with Kapton tape. The oven mitt was quite inexpensive, and even after removing enough for a couple of hot ends, I still have enough mitt left to use around the oven!

Mike