Cartridge Heater Upgrade unable to maintain temp with fan on

[cassetti]

In addition to my continuing issue with leveling the bed through calibrating tower rotation (see other thread), I have been having a strange issue.

Previously I had been using two power resistors and a fan mounted between the X and Z rails on the platform (blowing directly on a spacer, not on the PEEK). Since I shorted out my thermistor in a failed print (4 months ago, found printer stalled dead in it's tracks, thermistor incorrecting rdeading 10C for room temperature, and discovered more inaccurate reading as I set temperature higher).

Since my crash I have done the following in the past month:

- Dismanteled the Platform and U-carriage on each cheapskate (Replaced the Delta Arms and U-carriages on each arm with new ones properly sanded to fit).
- Replaced 40mm fan with tiny 20x20x10mm fan I purchased from Amazon.com
- Installed a brand new 100k thermistor
- Replaced power resistors with a new cartridge heater from hotends.com
- Calibrated the Printer-Radius using the updated documentation

The cartridge heater heats up faster, I guess, but it's hard to tell since the last time I ran the printer before shorting the thermistor was 4 months ago!

I did not replace the Rambo 1.1 board, but it appears to be functioning properly. I can read proper room temperature, (19.7C according to the LCD), and it can maintain temperature when sitting still (not printing).

*HOWEVER* when printing anything, as soon as I begin layer 2 which includes a slight temperature change (from 215 to 205), and the fan kicks on (35%), I cannot maintain temperature! Even though the temperature is set to 205 and the temperature graph shows full power applied to the thermistor, it doesn't appear to have enough power to overcome the tiny 20x20mm fan!

Is this normal?

I have performed the PID Auto-Tune function twice since the massive upgrade, but both times the PEEK fan was off. Should I turn on the PEEK fan prior to running the PID autotune?

For what it's worth - I just timed my heat up on the hotend from 19.7C to 200C - Approximately 4 minutes with hotbed pre-heating concurrently.

[Toyguy]

As I understand it, and I did it this way, you should absolutely be running the PEEK fan while doing the PID calibration.

Another thing that comes to mind is what wattage is your heater cartridge? I've seen both 20W and 40W. If it's 40W, you only need the one, but if it's a 20W you need two of them.

Dave

[cassetti]

I suspected as much.

What speed should i have the fan set to? 100%?

Here is the cartridge I purchased - https://www.hotends.com/index.php?route ... duct_id=91" onclick="window.open(this.href);return false; - 30 watt

[Eaglezsoar]

I suspected as much.

What speed should i have the fan set to? 100%?

Here is the cartridge I purchased - https://www.hotends.com/index.php?route ... duct_id=91" onclick="window.open(this.href);return false; - 30 watt

30 watts are uncommon, the majority of them are 20 and 40 watts. This could be a source of the problem.
Normally one 40 watt is used. Some have used two twenty watts. You may want to secure a 40 watt and give that a try.
If you put in a 40 watt make sure the peek fan is on at 100% and run a PID Auto-Tune.

[Toyguy]

Well, I have my PEEK fan hard wired so when the machine is on, it's on at full speed. I saw some discussion here that said you basically want it on all the time, regardless what filament you're using. You need it with the higher ABS temps, and so far it seems to do no harm with PLA.

With a 30W cartridge, I think you're 10W underpowered so it wouldn't surprise me that you have trouble holding temperature. I've seen here people discussing using either a single 40W cartridge, or a pair of 20W cartridges. You may want to look into those options.

I'm going to go E3D shortly, so that will allow me to drop the PEEK fan and get rid of some effector wiring. It also uses a 40W heater cartridge.