PLA Heat Creep - SOLVED

Looks like you have a good solution for the dual head. I will download your parts in the next few days and try it myself.
There is darn little space for the heat sink fans on the dual head.
Thanks for posting this! :slight_smile:

Bill D.

You’re welcome. If you do try it, let me know how it works out. Here’s a link to the fans I am using:

http://www.digikey.com/product-detail/en/sunon-fans/MC20080V1-000U-A99/259-1544-ND/2757793

After I completed the 11-hour PLA/PVA print yesterday, I did an 18-hour print overnight that was 100% successful, and now I am 5 hours into another that is going to be even longer. All of these without the extruder body fan on. It does seem like this has solved the problem.

Update:

While I may have jumped the gun in naming this thread, I believe that with my latest fan and shroud upgrade, I have actually truly eliminated the heat creep problem on my machine.

I have created a new thread regarding this mod, and have asked that it be added to the Taz list of modifications:

https://forum.lulzbot.com/t/dual-extruder-v2-heat-block-fan-upgrade/3366/1

I also believe that the parts may fit and work on the single head, maybe someone can verify that.

I’m getting great prints in PLA with PVA support now, which is a really big deal for me. I am very grateful to everyone who helped out!

Could you post a link to what fan you bought?

Is installing a new fan difficult? I have never gone through that process before. Thanks! :slight_smile:

Hi CheezeJam,

I posted the everything on “Thingiverse” including the print files, and where you can buy the fans, etc.
Here is the Thingiverse" link:
http://www.thingiverse.com/thing:1461335

Here is the link for the particular 25mm fan that I bought on Ebay (also given in the post on Thingiverse):
Uses this “2510”, 5 volt, 25x25x10mm muffin fan
http://www.ebay.com/itm/281384106214

If you don’t wish to buy on Ebay or wish to buy from a more traditional source, here is a link to a Sunon 25mm muffin fan on Digikey:
http://www.digikey.com/product-detail/en/sunon-fans/MC25100V2-000U-A99/259-1569-ND/2757806

You need a 5 volt, 25mm muffin fan for my duct design.

I’m loving this set up, by the way. It cures the root problem that caused jams and clogging with PLA and other filaments.
When you make one, take a photo, post it on Thingiverse as an “I made one” and let folks know how it worked for you.

Bill D.

Thanks! Do I need to splice wires together when installing a new fan, or can I simply unplug the old one and plug the new one in? Never done an electronic swap like this before on my Lulzbot Mini.

The 25mm fan is generic and not “plug and play”.
You will either have to cut the old wires and splice the new fan wires to the old ones, or
you will have to carefully remove the old fan pins from the connector, crimp new pins on your fan wires, and put them back into the connector where the old fan wires were.

Most folks cut and splice the fan wires. It is generally the simplest solution.
I had the pins, crimped them on the new fan wires, extracted the old fan pins, and replaced them with the new ones. I happened to have the correct pins on hand and the correct crimper, so it came out neater and wasn’t that difficult for me. The crimper is the most expensive part, but you can solder on the pins and/or crimp them with a pair of needle nose pliers, (kind of.)

Bill D.

Okay, thanks!

One other question: the .stl for the fan mount is really small. Should it be scaled by 25.4 (seems like the .stl was saved with mm dimensions instead of in. dimensions).

Yes. I created it in Inventor and the units are in inches. Cura assumes the units are in millimeters.

I probably should scale it by 25.4 :blush:

Bill D.

Okay thanks, just checking!

I haven’t used Inventor a lot, but in SolidWorks, when you save a model as an .stl, you can tell it what units to use, regardless of what you used when modeling.

I just got 100% reinforcement that the fan replacement works. I had printed out Billy D.'s fan shroud and put a cheap 25mm fan on it and it did indeed cure my clogs and filament stripping. Then a few days ago I got a clog again. I thought, now what? After close inspection I found that the fan was not turning as fast as it did when I installed it. In fact it was rotating at less than half speed, hence the clog. I spent a few extra bucks and ordered a 25mm Orion fan from Mouser Electronics and boom, problem solved again, but for good this time. Moral of the story, do yourself a favor and get a decent fan or you will be replacing it again. I wonder why this fan upgrade isn’t stock on all Lulzbot printers.

Many of the fans I have seen are only rated to 70C. In fact, the Pelonis blower that comes stock is only rated to 70C, as is the 20mm Sunon fan I replaced it with. I’m sure it is a complex equation, e.g., if the fan is running all of the time, what is it really seeing? But, printing ABS with a 240C extruder over a 110C table has got to be pushing it! I wouldn’t be surprised if some of these fans are wavering.

All muffin fans are not created equal.
What you look for is “ball bearing(s)” or Sunon’s “vapo-bearing” instead of “sleeve” bearings or no specifications at all.
Muffin fans without any bearing specifications are typically sleeve bearings, which are the least rugged, shortest lifespan, but are also the least expensive.

So far, the inexpensive sleeve bearing fans I bought on Ebay are working fine. If they give me grief, I’ll replace them with more expensive ball bearing fans. Ball bearing fans will cost ~$15 each instead of ~$3 I paid, however.

I should note that it is important to leave the power on (and the little fan running) for a while after your print has finished. Let the nozzle and heater block temperature cool off to ~30 Celsius or so, then switch off the power. If you don’t do this, the parts that are normally cooled by the fan, aren’t, and the fan, duct, filament left the extruder, etc. can get quite toasty from the latent heat of the heater block spreading out to the adjacent parts. This might be why your fan decided not to work so well after a bit of use. Might be something caught in the fan, like a bit of hair, or some other crud. Might be simply “infant mortality.”

Bill D.

Very good points Bill, especially about letting things cool before turning the machine off. I generally do that, but I hadn’t given it a lot of thought. Fortunately for me those little Sunon fans are hanging in there, because there aren’t a lot of other choices when you get down to the 20mm size.

Unfortunately they are a wee bit on the loud side, but after all the drama I went through with PLA, it’s knida like music to my ears.

Unfortunately the fin cooler only slightly extended the layers before fail. I’m using this fan (http://www.newegg.com/Product/Product.aspx?Item=N82E16835119098) on a seperate power supply at 0.04 amp 12v.


Did you guys update your PID when after installing the new cooler?

I did not. Do you think it’necessary, and if so, why?

from my understanding, the PID calculates the amount of energy to apply to the hotend, so it could be the direct cause of heat creep (the fan being can only cool so much when heat is simultaneously being applied).

I’m really at a loss on how to fix this…

So far I have calibrated E-steps (about 30+ added to get 100mm extruded accurately)
Calibrated bed, and also countlessly played with first layer height

Currently: Trying different low temperatures (on stock PID /Firmware)

Have not done in a while: Disassembled the toolhead >> hex tool re-assembly

I used a 25mm Sunon fan from Digikey. It works great, though is a fair bit louder than the stock one. I don’t mind it though.

259-1569-ND is the part number, $13 shipped to me.

PIDs are a complex subject… The basic idea is that they calculate times on/off to compensate for overshoot and maintain a stable temperature. You shouldn’t need to mess with them unless you directly change the thermal conditions of the hotend or bed. As we are working on the heat-break, I don’t expect it would affect the thermal performance of the actual hotend enough to matter to the PID controller. If you watch a graph of the temperature, it should look about the same as stock, it does on my mini anyway. If you see larger fluctuations, you might want to recalibrate.

With fans that move a lot more air, should that air hit the nozzle or heater block, it could cause an issue. If your hotend fails to maintain temp, that could certainly contribute to the filament stripping.

3.0 CFM fan… nice! I will give this a shot.

Until that arrives, I’m going to level my frame and disassembly tool head… :question:

Look at hotend temperature on the LCD display. If it is getting to temperature OK, maintaining temperature OK, and not overshooting by more than a couple of degrees, then the PID control needn’t be adjusted. If you notice a problem, then there is an “autotune” feature built in that will adjust the three PID parameters, Proportional, Integral, and Differential, to close to what they need to be. Here is a link to a guide on the Marlin software PID autotune:
http://reprap.org/wiki/PID_Tuning

I haven’t felt the need to change anything about any of the three (four?) PID temperature control loops in my firmware. Seems to be doing exactly what it is supposed to be doing. I tend to follow the old adage: “If it ain’t broke, don’t fix it.”

Bill D.