Detailed Documentation of our hardware and software mods for reliable printing

[Torgeir 242]

Oh no, -not brave, started with a cold iron to see if there was any problem...

But, it's a very good insulator.

BTW. also tested the high temp glue (1100 deg. Celsius). It worked on PLA and Aluminium foil!

(Need (2-3) hour in room temperature to cure.)

Torgeir.

[Torgeir 242]

Hi Folks,

As I've modified my spare extruder, now it's time to do the extruder that's removed from my printer.

First, here is a picture of both extruders. The right one is the spare one, still have some issues to be fixed before I can use it on my printer..

You'll see the Alum tape I'm using to have the pressure center at the nozzle. Also you'll see how the wiring from the heater block shadow the inlet for the cooling fan.

This next picture is after this modification on the extruder normally installed on the printer.

First, this modification on the used heat block was not an easy task. So if you're going to do this modification you need to have some spare part aviable in case something break, because here it is very easy to breake the wiring esp. the one for the heater element. So do not rebend the wires, they should stay in same position as it have under the whole modification!

I've had to power up the heat element in order to unscrew the adjustment screw for the Teflon coupler, as there was a sign of black plastic at the connection to the heat block. I'll think heating also is a good thing to do before trying to remove the heater element.

As I added the copper paste into the heat block attatcment hole's for both the heat element and the PT100 from before started using it, there was a minor task to remove them.

So, now you're warned about the problem that's may occur if you like to do this modification.

OK., here is a picture of the split-ted extruder, just before I connected the heat element to an external power supply using 12 VDC only. Using this voltage brought the temperature up to around 130 deg. Celsius.

The gap between the Teflon coupler and the adjustment nut is a little bit lo, only 1 mm..

Heating up to 130 deg. C.

Here is the hot block attached to my "mini" vice.  This block have more than 300 hour in printing, well, not much but still nice. You'll see I'm using the copper paste at the thread here as well.

I've had to clean up the threads with this tool, no need for adapter here, only bare hands! Be very careful if you need to clean away plastic using this method.

Here is the "essence" of this modification, the printed duct from James and related parts.

I've somehow come to the limit of how much I could upload, so next time I'll compress the pictures.

Just one more thing to mention is that I've had to make a cutout where the wiring going into

the extruder plastic housing, the same way the Chinese did it on the spare extruder housing from China.

Anyway, this is the way I did this modification.

Thanks.

Torgeir.

[Torgeir 242]

Hi Folks,

A last report about the testing after this modification.

When I loaded a roll of black PLA (Verbatim), the usual thing happen and it started to extrude filament out of the nozzle, then I heard the feeder stepper started to skip. As I watch this, it seemed to have a little less flow than before and the feeder act as it was compressing a "strong spring"! Every time it skipped it moved about 90 deg. back, then started to compress again. I was wondering if there was any remains/gums etc. inside the nozzle, so I did a few "atomic Bob". To my surprise the filament broke of right at the top of the Teflon coupler, I've had to reload manually and squeeze out a little PLA. After this, let the temp go down to 60 deg. Celsius, then set it to 90 deg. C and when at 90 deg. pull..

Then it come out "almost as" normal, but -just about where the Teflon coupler is insulating the heat block from the upper "cold part" of the extruder there was a circle/section of the filament with less diameter than the filament diameter(2.95 mm).

This set me somehow out.. After some thickening, I realized that I've lifted the heat block a little up. Aha., so I reduced the gap back to about 0.8 mm and made another test, bingo...

The little fan improved the cooling so much that is also cooled more of the upper part of the heat block. So, the faster the filament was tried to be feeded through that passage the more energy was needed to melt the filament.

So now I'll know how important the adjustment of the height of the Teflon coupler is.

You're actually adjusting the width/sharpness of the hot/cold zone for the hot end.

As a final test I printed the "extruder feed test", started with the temperature of 205 deg. Celsius and monitored the temperature until finish. When the temp descended one deg. I rolled it up one deg. more and so on.  It finished at 207 deg, Celsius with no issue..

All in all, I'm very pleased with this result.

Thanks.

Torgeir.

[Torgeir 242]

Hi Folks,

As a follow up, I'll like to post some of the remaining issues that James Strawson pointed out in his post found here:

https://ultimaker.com/en/community/17794-detailed-documentation-of-our-hardware-and-software-mods-for-reliable-printing?page=1&sort=

As they figured out that the track line made by the feeder wheel on the filament was running on the outside of the bowden tube, they turned around the feeder unit to make the track line move the lower side track along the bowden tube. This little detail improved the printers failure rate drastically, since the less friction in the bowden tube improved very much.

(This was a kind of surprise for me, cause I never had any problem with my feeder and never noticed that the UM2 had the feeder turned the other way.)

James also suggested installing another feeder wheel, a new hobbed wheel, this one:

https://www.amazon.com/gp/product/B00XP3NJSE?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s01

This is a wheel with a diameter of 6.7mm across the bottom of the hobbed part, improving the grip as well giving a little more torque.

I found this very interesting, as I've been experimenting with a double wheel feeder that's using MK 8 feeder wheel from RepRap.

You'll find all those feeder wheel here:

http://reprap.org/wiki/Drive-gear

The interesting thing is this MK 8 feeder wheel can be used on both, (3 and 1.75 (edited)) mm filament.

The MK 8 feeder wheel measure 7.5 mm across grove section (where the filament go), however, they use to say that the efficient diameter is 7 mm.!

I did some reverse engineering, calculating from the ideal step setting (UM2) 282 step/mm in order to find this (calculated) diameter of the original feeder wheel and got the number of 7.2 mm.  So our knurled feeder wheel that's measures just close to 8 mm is «reduced» to 7.2 mm, -interesting!

Well long story short, I just installed the MK 8 into the stock feeder and did not perform any adjustment of the E-step.  It perform as before, full flow test with absolutely no problem.

I'll think that, since I'm using quite a hard PLA filament that's prevent the hubbed part to go that deep into the feeder, so all in all the diameter is more or less the same for both feeder wheels when it come to practical use. But ofc., it will all come to the properties of the type (hardness of) filament we are using at any time.

Here is a picture of my setup using MK 8.

Thanks

Torgeir.

Edited October 16, 2016 by Guest