Printer freezes at start of print

jumpedwithbothfeet

@PaulHew @Phaedrux, so I have some feedback about this issue, I’ve managed to do multiple prints today which I’m very happy about, and I’ve figured out the bug.

Every time the printer is turned off and restarted the height map won’t apply, it loads and displays but that’s it, once a G32 has been carried out again you can print back to back with no hang ups until you turn the printer off, now I don’t have power off resume added to my config.g so I can’t test it but if a power loss occurs I would assume a restart print wouldn’t be able to be done.

Another thing I’ve noticed is on start up the hot end is always active wouldn’t it be safer to default it “off”?

Cheers Jim

PaulHew

@jumpedwithbothfeet Hi Jim, can you post your latest config.g please.
Just realized what you are referring to.

Unless a temp value has been selected, either manually or by Gcode, it will not heat.
Its just ready to go is the way I view it.

If the 'Turn Everything Off' was working no disrespect to the cleaver people, it will go into 'Off' state.

As @Phaedrux said, there is a new release of RRF3 coming out soon along with a new DWC also.

Glad you are printing again, how are the prints coming out?

Regards,
Paul

jumpedwithbothfeet

@PaulHew, Hi Paul, I printed a calibration cube and that was an abomination but I also printed a model and that came out brilliantly, I'll be running through some more calibration tomorrow and try and get it dialled in further.

config.g

Regards Jim

PaulHew

Hi Jim,

Its worth doing this if you havent already

Heater tuning
https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

Regards
Paul

Phaedrux

@jumpedwithbothfeet said in Printer freezes at start of print:

Another thing I’ve noticed is on start up the hot end is always active wouldn’t it be safer to default it “off”?

How it behaves at startup is entirely up to you. Typically though, there is a G10 command in config.g which sets the tool active and standby temps to 0 (off) and then a T0 command which sets the main tool as active, so that when you send a temp it starts to heat.

For example, from your config.g

G10 P0 R0 S0                                ; set initial tool 0 active and standby temperatures to 0C

; Custom settings are not defined

; Miscellaneous
M501                                        ; load saved parameters from non-volatile memory
T0

If you didn't have those commands, the starting temperature would show up as -273, which can be confusing, and you'd have to manually enable the tool by clicking it active in the web control or sending a T0 command manually or in your slicer start gcode.

jumpedwithbothfeet

@Phaedrux ahhh I get you so there is no way the tool even tho marked as active could have a temperature other than 0 applied, so for arguments sake and bearing in mind my electrical education is sorely lacking, if their was a fault with the hot end thermistor on start up the hot end could have heat applied?

so to counter this if I uncomment the G10 line the tool would start up in "off" but with a temp reading -273 until the tool is made active?

@PaulHew yup I have carried out the AutoPID on both bed and heater, however you have just reminded me that I did the hot end with out the part cooling fan on and the nozzle heat line was a little bumpy during printing yesterday so ill do it again with it on!

Regards Jim

Phaedrux

@jumpedwithbothfeet The heater is starting in an off state as it is. 0 is off. The tool is active. As in selected and ready. It won't heat unless you give it a temperature target in some way.

If a thermistor fault happened it would detect an abnormal temp change and halt with an error. If the heater itself faulted into the on position and started to heat on it's own the duet would detect that too and try to stop it if possible, but if it was truly faulted as a closed circuit with full power there's not much you could do other than a thermal cut out.

So in short, the real failure situation requires either a heater that is only powerful enough to get hot enough to melt the filament but not hot enough to melt the aluminum heat block. Or a thermal cut out to cut power entirely to the heater cartridge if the temps got too hot.

Those risks and solutions are the same regardless of if the tool is selected at start up or not.

So you're right to be worried but you're worrying about the wrong thing.

Never leave the printer unattended while powered on. Have a smoke detector and fire extinguisher handy. Choose heater wattages reasonable for the task. Install thermal cutouts where possible. Use ground fault interrupters on the AC outlets. Use a fused power switch. Ground the frame. All that sort of stuff is what's going to make the difference for safety.

jumpedwithbothfeet

@Phaedrux Thank you for the explanation, the only thing I don't have are the fire extinguisher and thermal cut outs which I'll look into further but I've not found anything suitable on that front yet as I'm assuming it would need to be mounted on the hot end

Regards Jim

Phaedrux

thermalCutoff.pdf

This might help.

The issue with cutouts on the hotend is that you can't really find a cutout that would survive long term at the temps we print at, so you need to attach a lower temp one to the heatsink instead. It also requires cutting into the heater wiring, which needs to be done properly to prevent a short from happening.

jumpedwithbothfeet

@Phaedrux thanks I’ll take a look see if I can source in the uk.