Letting Ultimaker 2 sit hot for hours creates block in Bowden tube

[gadgetfreak 7]

We received a second UM2 unit yesterday and I printed a little test piece fine after calibration.

Then we needed two bigger models (house/architecture) taking around 8-10 hours to print. 30mm/s, 0.1mm layerheight.

I didn't have too much time so I just started the print with the supplied Ultimaker silver PLA.

On coming back the next day,I noticed that the feeder had stopped extruding, but the hotend was still hot and "printing". The model had come off of the platform and not much PLA had been extruded in totalt, just a few layers.

 

The filament closest to the hotend had expanded - I guess because of heat creeping up?

I had a spare bowden so I quickly replaced it. This time I switched to Colorfabb white PLA/PHA (known good) and started the same model.

This time I did some manual recalibration of the bed but it might have been to close to the bed still because the same thing happened again (but the part of the model was still on the bed).

I think it stopped feeding in both cases because of pressure building up because the nozzle might have been too close to the bed (but I'm not sure).

What worries me is the heat creep. Is it really normal that the filament expands so far up in the Bowden tube?

It's very hard to get out. I managed to remove the filament from one of the Bowdens by using a small 1.5mm drill, drilling a few centimenters into it and using the power drill to pull it out.

It's not uncommon for the feeding mechanism to stop feeded every once in a while due to dusty filament, improper bed level etc. But if the implications of it is that you get a Bowden blockage then I think that a couple of spares should be included with each new Ultimaker.

Else people will get tired of 3D printing quickly and that would be sad.

 

[IRobertI 520]

Have you checked that the rear fan on the head is running? This has been an issue for a lot of people where the connector for that fan has been dislodged in shipping. And since the job of that fan is to keep the transition zone between hot and cold sharp I imagine that could be the problem here.

 

[gadgetfreak 7]

I'm not at the office any more but I'm 99% sure you must be right!!

I recall the new unit being more quiet than the older one when being turned on....

Thanks

[gr5 2,173]

The third fan (not to be confused by third eye?) comes on the instant you switch on the UM2. Even before the lights. So that is useful debugging info. Usually you simply lift up the woven cover above the print head and that exposes the connectors. The side two fans are in serial on the same circuit (you can see a short wire connecting the connectors. The rear fan has it's own separate power.

 

[illuminarti 18]

In a couple of cases, including mine, the wiring was apparently ok, but the polarity was reversed; rotating the non-keyed connector at the motherboard end is the easiest way to fix it, it that's the case.

 

[gadgetfreak 7]

illuminarti: So no risk damaging electronics by reversing polarity?

I recall I blev the Darlington transistor on my very first Ultimaker a couple of years back when polarity was reversed on the side fan...luckily it stayed turned on but I could never shut it off. In the end I actually replaced the whole motherboard to get new connectors for new NEMA motors etc etc

 

[illuminarti 18]

No, I don't think so. Ithe UM2 fan is always on, so it's wired straight to 5v and ground. I actually did blow up my first fan, because in trying to figure it outt, I plugged it into the nearby 'fan' socket - which it turns out is 24V.

But then I wired my replacement fan the same way round and it didn't run - reversing the plug fixed it. I also tried a couple of other similar brushless fans wired directly into a desktop power supply, and they didn't run with reversed polarity, but ran fine with the wires the right way round afterwards.

[gadgetfreak 7]

Good to know. It would be nice to find a replacement that is more silent. I find it pretty loud...

 

[illuminarti 18]

I couldn't get the exact model as the one that died on me, but I got a close cousin (same spec, and almost identical part number). It is, to all intents and purposes, silent. I have to actually look at it to see if it is running...

This is the one I got...

http://www.digikey.com/product-search/en?x=11&y=15&lang=en&site=us&KeyWords=259-1573-ND

 

[gadgetfreak 7]

That is a really good tip Illuminarti. I wanted to order one right away but it turns out I could not order the one from Digikey...I had a chat with their support:

"

 

Judy_ext_2876: I am sorry, but due to contractual agreements with the Vendor, we are unable to export the part you have requested. Would you be interested in a Substitute from another manufacturer if one is available?

 

Daniel Sjöstrand: oh

 

Judy_ext_2876: Usually this is because there is another distributer in your area,

"

I am now googling for other distributors in Sweden/Europe

 

[Daid 306]

Uhm, yeah, Digikey also refuses to ship those fans to us... silly stuff, as we did not find a supplier for the exact same model.

Anyhow, if the fan was broken to start with, you should get a free replacement from Ultimaker. After all, you payed for a working machine.

 

[gadgetfreak 7]

Thanks Daid.

I'm not sure it's broken yet, I will check tomorrow on loose cables when I get to the office.

However, my main concern is the noise. I would like to exchange the fan to a silent one.

I found that exact Sunon fan at "TME Electronic Components":

http://www.tme.eu/se/katalog/?idp=1&search=MC25060V2-000U-A99&cleanParameters=1

It's 5EUR for a single one. For 50+ it's 3.85EUR per piece.

They do not have it in stock, it can ship mid January according to their order system (I had to register).

I will not order quite yet, will see if there might be any local options here in Sweden first.