Firmware adjustment for E3D V4

I just updated the firmware on my board to the newest one posted 2/6/14 and since then I have noticed the temp on my hot end jumps like crazy (for example it will be set to 250 it will go down to 230 then skyrocket to 245 then suddenly 260). All I can think is that the settings for the transistor is different compared to the original firmware. Anyone know which setting to use for the E3D V4 hot end?

 

First, be sure you set your thermistor type to semitec 100k in the settings if it's not.

Second, you should run an autotune at 250C or 275 or so. http://reprap.org/wiki/PID_Tuning

Using the command:
M303 E0 S200 C8
It should spit out some numbers once it done then you'll input that back into the firmware. This should help with your overshoot.

 

Thank Mike! I will check if it is the semitec and then try the autotune

 

I use high-temp gasket RTV Silicone so I don't think it is that. I'm about to finish a print and then try adjusting the firmware as Mike mentioned, I am 99% sure it is that as previous to the new firmware I was golden

 

Big thanks Mike! That did it. Now it hardly fluctuates and if it does it's .5 degrees.

 

Mind sharing your values?

 

Well strange. It seemed good for the first few uses but now is bouncing around again. I'm going to try running the autotune again, when I ran it it gave me MULTIPLE sets of values, almost like it ran, then continued to run another 4 times.

 

it'll output a set of value, then rerun the cycle using those values to pull new values, and repeat. Depending on the number of cycles you tell it. The above is set to 8.

You need to let it run all 8 cycles before pulling the value.

Also the above code is set to run at 200C. I heard of someone who ran their PID at like 250-260C and with those values had much better control at 200C. Might try that.

 

200 is correct. I was going to say: Average all of the values. PID Autotune is issuing varying current to the heating resistor and measuring the thermistor value. Cycling gives the device and the head time to cool down, come back up, etc - under different loads. But this firmware provides only one pass.

Proper PID settings even out the temp curve (in Repetier). It makes for a more even print.

 

The newest Marlin (3/14) has protections built in. I'm trying 190. (M303 E0 S190 C8)

EDIT: Not recommended but here is what I did: Change PID_Max to 140 - it slowed down the current to the head and allowed a full autotune to run.

 

So is changing the thermistor type something I really should do? I never did; not necessarily seeing any bad ranging effects but I'm wondering if I really should. Using the E3D thermistor.

 

Actually, I used Ultimachine's 100K. It has a larger bulb but I always thought 100k is 100k... - but for some reason the protections kicked in. It read about 100K when I measured it before putting it into my set screw thingy and it read similar to the tiny 100k thermistors.

The E3D 100K thermistor (NDC brand) are the go-tos I think. Three printers, work great as long as they don't pull out - of course that goes for any of them!!!

Change? Nope, the tiny 100ks work just great. Not trying to fix what's broke here, they work. I was just forced to use the large bulb ones and they had different characteristics.