defining extruder max/min temperature in marlin...

...when PID is disabled and extruder is set to "bang-bang".
Is there a way to set parameters like hysteresis and check intervall for the extruder temperatur? There are settings I can define for the heated bed in the advanced cofiguration file but I can't find anything similar for the extruder.

I know it sounds unusual but I'd like to see the effect it has on the surface of the printed object.

Am newb on the code, but...in configuration.h

TEMP_RESIDENCY_TIME and TEMP_HYSTERESIS

look like possibilities.

You can send temperature changes from the console while it is printing with pronterface if you want to see how it affects the print.

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[www.hydraraptor.blogspot.com]

@xiando: I tried this already. It seems it only affects the M109 command and not the actual printing process.

@nophead: this is not what I wanted to do. Atm I believe that these temperature settings have a great influence on the surface quality of the printed object. I found out that switching off the heatbed suddenly gives a much smoother surface. When I switch it on again, the surface remains smooth until the heatbed reaches the defined temperature again. From then on the surface is like before. I'm using PID for the heatbed now and it's much better now but there are still some irregularities in the print and I think the PID control for the extruder might be a reason for this. It's not actually the difference in the temperature but possibly the (irregular) changes in the current when the board tries to compensate these differences. When I disable PID for the extruder (and enable "bang-bang") these changes are rather regular. This has an effect on the surface of the printed object. It's not as smooth as with PID enabled but looks more regular. The temperature without PID is +/- 5°C atm and I'd like to reduce that so I can see if I can get a better result. I might be totally wrong with that and I know it sounds like going back into stone age but I'd hoped there might be a way to test this. I'm using a printrboard atm and I also don't know if this might be the reason for this effect. I'm a newb on this too and as I said: I'm probably totally wrong with that...

But I'd like to find out....

Bang bang doesn't work well with Marlin because it samples the temperature too infrequently.

Can you post a picture of the effect?

The bed temperature swing with bang bang has been known to cause the bed to more up and down when the heating element is stuck to a glass but I can't see what effect PID would have if the nozzle temperature is constant. The heater current will be varying but how does that affect surface quality?

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[www.hydraraptor.blogspot.com]