E3Dv6, jimc's extruder and excessive cooling

[loiphin]

Hey all,

Not sure if anyone else is having this issue, but I found that when printing PLA with my E3Dv6 and jimc's extruder setup, I get excessive cooling on the hotend. So much so that the heater on the E3Dv6 can't heat up the block any further. This is during the first few layers. Once the head has lifted a centimetre or so, the cooling is not as drastic. When printing at 215 degrees for PLA, the temperature drops to 202 degrees at the worst point. I have included an Octoprint graph. In this particular example, it takes a good 10 minutes to recover. My PID's have been autotuned correctly. To me it looks like I need to modify the fan duct so that it sits closer to the glass, and blows less on the heat block. I am using a pretty standard 24v ball bearing fan.

And I am running the newer E3Dv6 with 25W heater, not the 40w one.



Anyone suffered the same issue and suggestions?

Thanks,

loiphin.

[jsc]

You could try rerunning the PID autotune with the fan on.

[Bratag]

No issues here. My hotend temp is pretty much a rock once I tuned the PID correctly

[jdacal]

I haven't had any issues with mine, been using it almost a year now. I do have to PID tune a couple of times when I switch hotends usually. One gets it close, the second gets it much flatter. Also make sure your hotend is completely cold before you tune it, you probably know that but I mention it just in case.

EDIT: Oh, just saw what you said about the 24W heater, I've never used that one so can't comment.

[loiphin]

I am starting to think this is nothing to do with PID's and purely that the 25W heater (sorry I originally wrote 24W in my original description) just doesn't have enough power to cope with the cooling from the fan duct. I see some other complaints over on the E3D forum. Guess it's time for a 40W upgrade.

[loiphin]

Attempted a PID autotune with the fan on, and here are the results.... hhehehe, the poor heater can even get to 215 degrees in the first place! So it means either a 40W upgrade or play with the fan duct.

[jimc]

You should look in the firmware at the max pid setting. This is basically a power limit. I have no issues with any one of my 4 e3d's. All are 24v but none are 25w. If that max pid setting is limiting power then your not allowing that heater to work to it potential.

[goopyplastic]

I seemed to always have this problem as I like lots of cooling with PLA, what I did was to wrap the heater cartridge up in a few layers of silicone fusion tape.

[loiphin]

I covered the heater block on the E3Dv6 with a few layers of Kapton to insulate it from the ducted fan. Seems to work a treat. I have a slight drop in temperature (4 degrees ) when the fan activates, but it quickly returns to 215 degrees.

I ordered some fibreglass fire sleeve 20mm ID, which will hopefully be the permanent solution. Something akin to the V3b's insulating jacket.

[loiphin]

Just a quick update. I ended up buying the 40W heater for the E3Dv6 anyway. I didn't really need it as the insulation on the heater block worked, but it sure heats up quicker now.