My corexy hbot configurations and build pictures

Veti · 29 Aug 2020, 06:43

@tracar said in My corexy hbot configurations and build pictures:

M305 P0 T100000 B4138 R4700 ; set thermistor + ADC parameters for heater 0
M305 P1 T100000 B4138 R4700 ; set thermistor + ADC parameters for heater 1

your thermistor settings are not configured properly. 4138 is the default and most likely wrong for your thermistors.

tracar · 29 Aug 2020, 06:51

@Veti
this i had no clue i needed to fix. what do i need to do to fix this ?

Veti · 29 Aug 2020, 06:55

@tracar

find out what thermistors you have and look in the spec sheet and find the beta value.

tracar · 29 Aug 2020, 06:58

@Veti
ahhhh , i had to configer these in marlin as a 6 on the old prusa
i think that was a 100k

Veti · 29 Aug 2020, 07:04

nearly all thermistors used today are 100k

marlin 6 is

6 : 100k EPCOS - Not as accurate as table 1 (created using a fluke thermocouple) (4.7k pullup)

not a good starting point.

where did you buy the thermistors?

tracar · 29 Aug 2020, 07:11

@Veti
think it came with the prusa, i3 clone from folgertech a few tears ago!!

Veti · 29 Aug 2020, 07:43

the prusa i3 clone comes with a mk8 hotend. are you still using that?

tracar · 29 Aug 2020, 13:28

@Veti has been parted out long ago.
after reading up on this thermister stuff, i see what you are trying to get after.
i dont think i have the info, but can find out by using a temp probe . Or just ordering some from amazon that the values are known.

Veti · 29 Aug 2020, 14:50

if you can establish the resistance at certain temperatures, then that would be perfect.

measure the resistance at something like 25, 120 and 240.

then use the https://configtool.reprapfirmware.org/Heaters click on the Beta value, select custom and enter those values.
It will calculate B and C for you. That would be more accurate as thermistors have variations that can lead to +/- 10 C.

Failing to do that you can buy a thermistor.
Preferable a Semitec 104-GT2.
I personally use a PT1000 (no daughter board necessary) for hotend and bed.

tracar · 29 Aug 2020, 14:53

@Veti said in My corexy hbot configurations and build pictures:

f you can establish the resistance at certain temperatures, then that would be perfect.
measure the resistance at something like 25, 120 and 240.
then use the https://configtool.reprapfirmware.org/Heaters click on the Beta value, select custom and enter those values.
It will calculate B and C for you. That would be more accurate as thermistors have variations that can lead to +/- 10 C.
Failing to do that you can buy a thermistor.
Preferable a Semitec 104-GT2.
I personally use a PT1000 (no daughter board necessary) for hotend and bed

i understand, even with my current setup, i notice, its always overshooting the temp around 10 degrees, but then adjusts it to where it needs to be.

Veti · 29 Aug 2020, 15:02

@tracar
that is an indication that you need to adjust the pid tuning.

see
https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

If during initial heating the temperature undershoots the target, reduce the A parameter. If it overshoots the target, increase the A parameter. Try increasing/decreasing it by 5% or 10%.

tracar · 29 Aug 2020, 15:10

so 3724.2 would be a good starting point

tracar · 29 Aug 2020, 15:16

@Veti said in My corexy hbot configurations and build pictures:

what about

M303 H1 S240 ; auto tune heater 1, default PWM, 240C target or maximum temperature

M303 ; report the auto-tune status or last result

Veti · 29 Aug 2020, 15:20

yes and save those values in your config.g

tracar · 29 Aug 2020, 15:27

the results of the M303 H1 S240

M307 H1 was used to get this info after the M303 H1 S240:

Heater 1 model: gain 869.9, time constant 308.4, dead time 3.1, max PWM 1.00, calibration voltage 24.2, mode PID, inverted no, frequency default
Computed PID parameters for setpoint change: P20.7, I0.672, D44.3
Computed PID parameters for load change: P20.

does it auto save this info? or how and where do i add this