Probing max temp

Exerqtor

For us running any from of direct nozzle z probing it would be nice to have a feature similar to the one klipper has. Where one can set the max hotend temp for probing, so we avoid wearing out or downright destroying the printsurface.

If the hotend temp is above the specified temp, it will get temporary lowered to the desired value, and once the probing is completed it returns to the temp it had before probing.

I've made a work around for this with using deploy/retractprobe.g together with some other files that saves the pre-probing temp and and a global that goes true while probing, and false after probing tohrestores the initial temp point.

But it would be nice to have this baked in as a feature in RRF. Maybe as an new parameter for G31 or something like that?

dc42

@Exerqtor, probing normally happens as a result of running homez.g (or homeall.g if it runs G30 directly), G32, or G29. In each case a macro is being run; so you have the opportunity to reduce the temperature and wait before probing, alert the user via M201 that this is happening, and restore the temperature afterwards. Isn't this sufficient? To reduce code duplication you can use macros to reduce temperature/alert the user, and to restore temperature afterwards.

Even better, unless you are using BLTouch you can do this all in deployprobe.g and retractprobe.g.

If we hard-coded this then inevitably some users would complain that the message wasn't right, or that additional actions should be performed. So I think this is best done in macros, for maximum flexibility - or perhaps you can provide an example that demonstrates macros to be insufficient?

deckingman

@Exerqtor As DC has said, setting the hot end temperature for probing is best done in your homing or probing macros. But Im curious as to why you think it necessary to reduce the hot end temperature if it is above a threshold. I use the nozzle as a probe and the reason I heat it is to soften any plastic which might have oozed out and which otherwise would give a false Z=0. I use a conditional statement in my macros which checks if the hot end is above a predetermined temperature and only heat the nozzle if the temperature is lower. I don't understand why you would want to wait for it to cool. Can you explain the reasoning behind this?

Exerqtor

@dc42
Guess that's all true, and how i'm currently doing it.

The reasoning on my end was to have it as a safeguard more than anything. To avoid a 250+ degree nozzle kissing the bed.

@deckingman
Like i touched on above i was thinking down the lines of avoiding having a too hot nozzle touching the bed surface. I run my nozzle at 150c when probing, to soften any oozed plastic, but I also don't want to have it much hotter than that since I'm quite sure it will leave marks in the PEI over time.

That said, i will keep doing it in the macros ✌️ And rather look into polishing the safeguards/how it's handeled in the macros.