Heat Capacity Limits Performance

[LesHall 95]

Hi gr5,

I see your point. I wonder what it could be then? I only did the test once, I will have to test more when I get home later this week. I have updated the firmware so that's ok. One possibility is that I am running a hardened steel nozzle that I bought here:

hardened steel nozzle for abrasion resistance

The guy who sold it to me said that it would have worse heat transfer capability than the stock brass nozzles. So maybe the heater is heating up the hot end and the thermometer but not as much of the heat is going into the nozzle and the filament is pulling heat away from the nozzle internally? I should have mentioned this before but I only just thought of it.

I am running PETG filament.

Les

[meduza 191]

Steel nozzles does limit your heat transfer rate, and therefore your maximum extrusion rate, that is a fact.

Edited February 27, 2017 by Guest

[gr5 2,266]

Brass is popular for 2 reasons:

It's nice and soft so very easy to machine

It has excellent heat transfer.

Steel not so good on the heat transfer. So I wouldn't leave the nozzle at 240C when you are warming up or paused but once you starting printing I would definitely heat the nozzle up 10C hotter than what you use for brass. If doing that gives you a "heater error", only then would I recommend a more powerful heater. I have 35W, 40W, and 50W heaters for UM2 in my store.

[LesHall 95]

That must be what was happening then, I will switch back to the brass nozzle that was included with the printer. The steel one is just for abrasive filaments anyway. Well, that or run it hot and fast!

Les

[LesHall 95]

I had further trouble when I got back from a month in hospital so I swapped the steel nozzle for the stock brass one.  The problem disappeared!  Have a look at this photo:  

The poor surface finish of the base is due to the steel nozzle's poor heat transfer coefficient.  The gears, however, are printed with the brass nozzle - nice fix!  

Thanks everyone for this thought-provoking discussion!  

Les

Edited March 11, 2017 by Guest