Heating Chamber for a 3d printer!

hackinistrator

add Q parameter to m950 to lower the pwm freq .

rexx

@hackinistrator its switching an SSR the HZ dont matter no...? as long as it within the spec of the SSR 3-32vdc 15mA control side
the switching side is mains power 6A 120 VAC (on or off) no ramping capability except pwm from the control side no?
if it means the frequency of switching i am in...but it says HZ hertz frequency usually 60 hz as is 120vac it is at 60 hz mains power which would not be adjustable without a VFD and/or winding's before it's heater

or maybe i am not understanding how this could benefit me other ways maybe algorithms at low HZ switch differently??

hackinistrator

@rexx it has nothing to do with mains freq . its the pwm switching freq .
heated beds and chamber heaters that are powered by mains usually use low switching freq , around 10hz .
also it will able you to see what's actually going on (led lights on when out on) .
i don't know what type of ssr you are using , some of them can't work at high freq , and some can . default freq is 250hz if you don't use the q parameter .

zapta

@rexx said in Heating Chamber for a 3d printer!:

or maybe i am not understanding how this could benefit me other ways maybe algorithms at low HZ switch differently??

Zero crossing SSR turns power on/off just when the mains voltage crosses zero level, and for a good reason, and that happens only 120 times a second. If you try to control it with 250hz PWM, it needs to turn turn power on/off 500 times a second which it can't do. Hence the use of 10Hz PWM which is low enough and provide some proportionality of duty cycle to power.

rexx

@zapta this is absolutely great thank you
what would my M307 look like with a chamber thats slow but keeps temps and is insulated well, what you would try first ?
is this only put in config.g correct?

is it 0.1 i am going to try it at 10 hz is 20 times a second still not to much?? i will try it!

Cheers

rexx

@zapta i tried S0.10 in M307 but seen that M950 is now where Q is used to set HZ so i am trying M950 Q50 M307 S1.00

S0.01 did light the ssr up but is not on,not heat at this but only faint dim leds on the out and ssr so i will try Q50 in the M950 and see tuning....

engikeneer

@rexx as the other have said, you'll want to use a lower pwm frequency to control the SSR, like Q5 or Q10. Q50 may not work for the reasons explained by @zapta

rexx

@engikeneer thank you i have stopped the tuning and have set the pwm to Q5 in the M950 and restarted the tune once back to ambient temperature again

rexx

@engikeneer what is a reasonable time to autotune i am at phase 3 but has been for 3.15 hrs and counting for a total of 4.5 hrs

when i send M303 it sais i am on 4 of 4 measuring but did not say it started to like 1,2,3 until i sent M303...

chamber 8.JPG

engikeneer

@rexx can be several hours especially for large slow heaters with long cooldown times like a chamber. By default it does 25 heating cycles to determine behaviour.
Your 2deg cycle may also cause it some confusion if there is some variation I'm ambient temperature during tuning

rexx

ok much playing with but i got it Q ended up to be Q1.25 and the switching is just like the oem original now and only +/-.5c spread the R was set to R0.030 which auto tune suggested R0.027 was close but the D was suggested to D159 by auto tune and D28 worked best for me

thank you to all whom guided me here the D,R and Q was the issues i was having and is a ok now!