Bundled questions

[Titus 170]

Ok, so I had a few small questions that I thought I'd bundle.

 

1) Starting with this print here:

 

Severe underextrusion going on there. Could it be caused by difference in diameter of the pla? Because I'm pretty sure the spool was loose and didn't cause the problem, also I didn't tweak the settings whatsoever during the print, and some parts are pretty perfect, others are shit. Same thing goes for this picture. It just seems to preform well, even had parts without a single underextrusion line, all the same settings.

 

2) Today I decided to fix my hot end, since Joris pointed out that my PEEK was against the heaterblock rather than the nozzle. Obvious mistake, I don't know how I didn't see that when I bought the printer...

Going from this(note the hotend)

 

To this:

 

 

When taking it all apart(very carefully not to break the brass/PEEK) I noticed these wires were not really in the best shape.

 

 

It's the first time I have a good look at them since I bought the printer. My guess is that sooner or later they will brake. What do you think? Is a preventive replacement advisable? Is that a standard part you can get in an electronics store? Should I get the same kind, or go for the thermistor with R23 installed. Which option is advisable?

 

3) I also opened up the bag with extra nozzles/parts I got with the printer and found this boy:

 

The teflon it self looks good, so I was wondering what the best way was to get the ABS out and salvage the teflon part as a spare one.

4) What is the best way to change a nozzle? I've been googling and looking in the forum, but the deal just seems to be: heat up, unscrew, done.

But I'd say you get some plastic in places you don't want it to be...

 

[gr5 2,172]

What is the best way to change a nozzle? I've been googling and looking in the forum, but the deal just seems to be: heat up, unscrew, done.

 

Yes - do that. It's really very easy. I like 180C when turning the nozzle.

I recommend doing a "cold pull" or "atomic method" first - heat to 180C, insert some PLA until it's coming out the tip, then cool to 90C and as soon as temp hits 90C pull it out the back (release the filament first - pull with hands, not gear).

This will leave you with a clean, empty nozzle before removal. But really is not necessary.

 

[gr5 2,172]

To clean the ABS out of teflon just heat it up. Around 230C the ABS will turn to honey and pour out. Around 270C the teflon might get a little soft but it won't get seriously soft until 300C.

So maybe just put it in an oven?

Or just cut off the piece of ABS and print it out by pushing PLA through from the back. 240C is a great temp to print both ABS and PLA so I would use that temp and print an entire robot before declaring it mostly ABS free.

 

[gr5 2,172]

Severe underextrusion going on there. Could it be caused by difference in diameter of the pla?

 

No. That might affect by 10% by this is at least 50%, probalby 80% underextrusion.

What is your speed, layer height, temperature for that exact print? This chart below (dark blue line) was written for UM2 but is correct for UM Original also - make sure you stay at half the print volume of the dark blue line for a given temp.

http://umforum.ultimaker.com/index.php?/topic/4127-um2-extrusion-rates-revisited/

 

[gr5 2,172]

Regarding issue #1 - it's also possible your Z stage is sticky and drops suddenly which mimics underextrusion because you have a .4mm space but only .2mm worth of filament to fill it.

 

[Titus 170]

Hi Gr5,

Thanks for your replies!

To add to them in order:

1) I'm not sure what you mean by sticky, and droping suddenly, how I would be able to observe it.

I was printing at

0.2 layer

0.8mm shell

1mm bot/top

with

100 mm/s

210 degrees

2.9 diameter

100% flow.

Now I'm printing at

110 mm/s

212 degrees

2.85 diameter

107% flow.

And that works great...

2) nothing to add yet

3) Yes, an oven sounds like a good idea! Cutting it off and putting it in the printer less, especially since I have a working teflon, peek, brass, aluminum, brass solution right now. I'd rather not change that This teflon on the picture is a spare.

4) An atomic pull seems the right way to go. I already did a few, but that was with the aluminium block removed from the peek. How would you do it without deconstructing everything? Take the bowden out the hot end and go directly through the wood/teflon? Or leave the bowden in the hotend?