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Anders Olsson

Custom heater block to fit E3D nozzle on Ultimaker 2 ("The Olsson Block")

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I (and I think ultimaker) believe the most common cause of underextrusion is the isolator. There are however quite a few other causes! There's about a dozen possible and common causes. Sometimes the nozzle is just *slightly* blocked - it has some crud all around the inside. This is not best fixed by getting a new nozzle but just cleaning it by burning it all away.

Still there are many other causes! Such as filament entering the feeder at a strong angle. Filament tangles (extremely common - typically you get a horizontal band of underextrusion) bad temp sensors - a bad batch went out I think last summer. Maybe. Not certain. Pressure on isolator too high. bits of dust and non-pla plastics getting into the bowden and making their way into the nozzle. Bad spring tension. Feeder knurled sleeve on wrong. filament too large a diameter getting stuck. Feeder motor too hot melting the pla a bit. print head screws too tight (this is more common than you might think!). And I forget what else. All of the things I mention have happened to people on this forum.

The odds that your particular problem is in the heater block or nozzle is very low.


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The melt zone on my custom heater block is about 4 mm longer than on the original heater block.

I have been using various iterations of the custom heater block for four months and about 500 hours now and what I can say is:

- I basically use the same settings as I did for the original heater block and I can not notice any major differences.

- It appears like the custom heater block can sometimes tolerate a bit lower printing temperatures, like 5-10 degrees, but it is nothing that I use.

- When pushing it, I mean far beyond what you would do with a 0.4 mm nozzle for normal printing, it seems the custom heater block can tolerate a bit higher extrusion rates.

All things above are consistent with the longer melt zone I would say.

The mass of my custom heater block including one 0.4 mm nozzle is about 40% higher than the original heater block.

This makes heating it up slightly slower, and potentially makes the temperature a bit more stable, but should not have any other effects. (As Daid reduced the sensitivity of the sensor monitoring function a lot lately)

I am probably not going to put more effort on calculations and measurements on the custom heater block, since the ones I have been using so far basically works as good as or better than the original heater block.


For the nozzle design, I encourage people to test different nozzles and report back their findings! :smile: (Just remember to level the buildplate when you change nozzle!)

There seems to be almost as many nozzle designs as there are printer models, all slightly different. Some probably can tolerate a bit higher flow, others have better oozing properties, and so on.

Which is better on what is quite difficult to get any information about though.


I agree with previous replies that the teflon spacer is the main thing to focus on when it comes to underextrusion issues.


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Gr5- A short time line so were all clear.

1250h printing with standard nozzle. Blue um filament needs 250C to close off top surfaces but will print walls OK down to about 230C. Other pla including other um colours close off top surfaces OK at about 230C. Calibrated temp prob inserted down the nozzle shows marked discrepancy between bots temp and probe temp. Don't understand why bit its a lot higher than it should be. There's images of the temp diff in my gallary (the forum doesn't want me to paste them here for some reason). Abs prints OK at 260C issues if temp refused.

[gr edit - added picture:]

20141211 172627[1]

Changed standard nozzle block for new standard block three days prior to fitting custom block. Chaged the isolator also (didn't have to as now deformation just some discolouration at the contact point). During the refit I had no option but to pull at the temp sensor as there was no metal cap protruding from the block which resulted in me pulling out the wires. So new temp sensor fitted (did not cross check the nozzle temp). Blue um pla still required 250C to close top surface. Only got about 20h printing with this block (fitted to ensure I had a good comparison for the custom block).

Changed to custom block with 0.4mm E3D nozzle. Didn't change anything else. Blue um pla now closes top surfaces a good 30C lower and ABS prints today where done at 230C. I've tried some colourfabb pla today also and that was printed at 205C (would not have ever tried to go this low before, would have previously used 230C).

Melt zone on the new block is 3.7mm longer than standard block.


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Ah - now I get it. The temp probe was changed but that didn't help. It was the new design block and new nozzle.

Well two things:

1) Temperature - a slight change in the position or conductance between temp sensor and block and between temp sensor and melt zone should in theory make quite a big difference to the temp inside the nozzle. It might be good to redo your test where you inserted the probe to see if it's even *hotter* than before!

2) There are many forces that the UM2 feeder has to overcome such as the friction in the bowden and in the isolator. But for a well functioning machine the highest friction is getting that molten plastic through the nozzle. The friction is higher for smaller nozzle holes and higher for *longer* holes at that smallest size (.4mm diameter).

The nozzle in the UM2 has a rather long .4mm hole. The e3d hole is probably much shorter and since the psi needed to get the same flow is linear with length, twice as long a hole is twice as much pressure needed for same flow of plastic. Even if the e3d hole is 80% as long as the UM2 nozzle, that's a significant difference. For example it might mean the difference between printing 10mm^3/sec versus 12mm^3/sec. 50% as long would imply printing 20mm^3/sec versus 10mm^3/sec.

Of course this thin hole is NOT the only friction in the system. But it is the biggest in the budget.


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So the left nozzle (e3d) should print faster - up to 20% faster due to the .4mm passage and maybe another 2% faster due to the wider area above. But when you put it all together I would guess only 15% faster (because there are other sources of friction such as the bowden tube).

On the downside, the left nozzle should drip/leak a bit more causing surfaces not quite as perfect - especially stringing. I would expect stringing slightly worse with the left nozzle (maybe strings 20% thicker?).


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Here is another more extensive comparison :smile:

nozzle comparison


The Ultimaker Original nozzle should fit the custom heater block, as I mentioned, in case you want to run comparisons.


I also mentioned before that there are rumors that Deltatower nozzles, which looks very similar to E3D-nozzles, have an different internal design: http://shop.deltatower.ch/Extruder-und-Hotends/0-4mm-nozzle-with-M6-thread::206.html

Would be interesting if someone bought and tested one of those.


You could actually even fit the Makerbot nozzles :???: :smile:

I would recommend turning down 1.5 mm of the hex grip to 5 mm diameter if you try though, for the sealing surface to reach the seat inside the heater block.

The Makerbot nozzles are smaller inside too (2.38 vs 3.2 mm), so it probably does not work that well unless you use 1.75 mm filament or drill the first 10 mm of the nozzle to 3.2 mm.

I designed the heater block to be as flexible as the design constraints allowed and I had in mind to test several nozzles including the Delta tower and the Ultimaker Original.

This did not really happen yet though as E3D nozzles appears to work just fine for what I do and as I had other things to keep me busy.

I encourage you to test other nozzles though, I am as curious as many of you probably are about if there are any differences in printing quality!

Just remember to level the bed when you change nozzle! (yes, i mentioned it before, but it is worth mentioning again :smile: )


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Hi I am new to UM2 it will be arriving after the 9th of next month.

I have a full blown machine CNC shop in my basement from when I had a businees of making Pro To Type parts for the manufacturing industry.

I would be interested in making parts and also a variety of different nozzles.

Once CNC code is generated I can just spit parts out.

If you want some assistance just contact me.

66 and retired!!!!



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If you level it, after the wine, .. you can start printing stuff like this:

Printed with different nozzle sizes


The woodfill part was printed mostly at 210, at the end I increased it to 230

(regret).. as you can see it is a little burnt.. Smell is nice, like in a woodworkshop.


Woodfill; layer 0.15, nozzle 0.80mm, speed needs experimenting. try 30mm/sec.

Material flow 125-135%. Retraction OFF.. this material needs to keep flowing.


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Welcome to the forum Fixer.

When you get your machine I'd recommend you spend some time with the standard heater block first so you can get a good feel for printing. You'll have a good idea for how to tweak the settings for the custom one then.

I've posted a drawing of my custom block a few pages back but I'd think it would be less hassle getting one of Anders block from Swordriff.

@@@@@@ Please note that if you intend to machine my one the slot depth needs to be doubled @@@@@

All this talk of wine.... Time to open a bottle!

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