pid and the hot end

stonewater · Post by **stonewater** » Sat May 09, 2015 11:21 am

so here is the tale...

I am in the middle of a 24 volt upgrade. the relay for the heated bed failed after 1 day. no more Chinese nock offs for me. a crydom brand one is ordered. any way I put everything back in with the old PS so I could keep printing. I ran a pid curve for both bed and hot end. put the numbers in like normal. pid temp for the hot end was 200 and for the bed 70. the bed heats up faster than before, but now it seems no matter what I set the hot end temp too it gets about 2 degrees from where it needs to be and it cannot seem to get any closer. if I disable the peek fan it heats up just fine. I cannot seem to get the peek fan to slow down enough to allow the hotend to get to a place where it can print. settings in mattercontrol do not seems to affect fan speed. that may be because it is just for the layer fan but I cannot tell if the fan settings are for the peek or the layer fan.

I thought perhaps there may be an eeprom setting I am missing. my default Idea was to put a potentiometer rinline with the peek fan and just slow it down that way.

Tom C

Nylocke · Post by **Nylocke** » Sat May 09, 2015 11:48 am

Adjust the PID Max power setting from 205 to 230.

stonewater · Post by **stonewater** » Sat May 09, 2015 3:39 pm

thanks nylocke, will try it tonight.

Tom C

stonewater · Post by **stonewater** » Sat May 09, 2015 9:39 pm

alright I modified the eeprom setting ran a pid for the hot end, input the numbers.... no dice, bummer I thought for sure that would solve it

Tom C

bot · Post by **bot** » Sat May 09, 2015 9:50 pm

Make sure nothing that is metal (like the nylon lock nuts) are making contact with the hotend or wires -- it will draw heat away from the hotend.

stonewater · Post by **stonewater** » Sat May 09, 2015 10:36 pm

thanks Bot!!

ok will do..... right now I am printing, I added 1K ohm pot in series with the fan... I know this is not the answer for the long run, but it only need to be about 10 percent slower and the hot end came up fine. any other suggestions would be appreciated.

Tom C

Lanty · Post by **Lanty** » Tue May 26, 2015 10:14 pm

Any luck with this?

I seem to be having a similar problem. I finally got around to hooking up my peek fan an now I can't seem to hit my 228 temp, falls short. I can un plug the fan and it get up to and passes that temp in just a few sec. I ran and re ran the PID auto tune several times with no luck.

I don't mind the POT solution as a temp work around (good thinking), but would like to get to the root of the problem.

stonewater · Post by **stonewater** » Wed May 27, 2015 12:48 am

nope I have just left this work around in.... there is a setting in config.h about max fan speed. some slicers have one too you need the eeprom changed for pid.... do not remember where it is.

Tom C

jram · Post by **jram** » Wed May 27, 2015 1:15 am

I had a similar problem even after doing a PID auto tune. I rewrapped the hot end in Kapton and then stuffed some fiberglass insulation around the hot end on the top and all sides. That took care of my problem, now it consistently reaches target temp with no problems .

JFettig · Post by **JFettig** » Wed May 27, 2015 7:24 am

Pid auto tune on these machines are very poor. Drop your I and d values down to about 1 and see what it does. Mine are perfect below .5

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pid and the hot end

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