Um2 hotend design questions

[Anders Olsson]

For those of you who printed the adjustable spacer: Did you have to scale the outer part to get a tight fit for the threads?

I recall getting too much play in the threads at some point which made the spacer collapse under load.
I can't remember though if that was one of the prototypes and the dimensions were adjusted later, if I it was due to some issue with the printer/filament or if it was related to different shrinkage for different materials.

If the current models prints well, I might just upload it on youmagine instead of letting dropbox host it

I did try to print the spacer on the Form 2 by the way, but the treads came out like this for some reason:

SLA is tricky in this sense, it is much more difficult to predict what will work and what won't than with filament based machines.

[Neotko]

I didn't scaled it. It fits nice and tight. One did break but because I played a lot with it. Last pla-tec version seems to work but since the material it's more flexible I think that might happen. I'll teport after the first week how it's going but so far everything nice and tight.

Oh one think I printed them simulating a 0.34 nozzle. That might change the precision of the print.

[Izzy]

I've printed the file as is using a 0.4mm nozzle at 0.05 layer height, fitted together ok not loose a nice transition fit.
With PLA part I found that if printing ABS the high temperature of the surrounding air caused the material to soften and with the pressure to slightly compress.
I would recommend printing the part in a High temperature material to prevent the softening in the hot print environment.

[Neotko]

I made an spacer with 2 position 9.4mm and 8.4mm
https://www.youmagine.com/designs/ultim ... 4mm-spacer

The think it's that I haven't tested it, but mainly because I think that with a better design than mine it could be posible to do a 3 positions adjustment without a screw. This way it could be posible to readjust it as much as needed, leave open areas to see the bowden and make it last longer.

Anyway I must say I haven't use it XD the one by anders just works.

I got the idea for this kind of spacer after seeing this:


Ofc on 3D print there's a limit to what we can do to interconnect the parts, but also, with almost 3mm distance for the spacer width, it could be posible to do some cool stuff with two rings outside and one inside so it 'fits'.

[Neotko]

Well the anders olsson spacer printed on black extrurd pla-tec died quite fast. It's soo slippery that the preassure makes the threads fail. Btw I wonder what technical applications could have this filament since its a bit flexible but also incredibly slippery even on the parts after sanding it. Maybe I should try to print x/y linear bearings, it fells to the touch as slippery as my bad igus linear bearings.

[gudo]

Hi Neotko
Can I submit to you this idea ?
It's a simple PTFE clip , it would be printed quickly( 15mn.) at the needed adjusted height ....

[Neotko]

Funny I did a design like that because I wanted to have a sollution to take out the coupler fast, but I forgot to take in account the height of the steelcoupler.

[gudo]

Neotko
for fun, I done a CAO simulation for a fast PTFE removing if use a "clip" system, it's possible under this condition which needs a machining work, that give enough space....

[Neotko]

Well yesterday was a pain in the ass.

I changed the coupler to the tft (milky) from 3dsolex and

First I got a leak. Ok cleaned all
Second I tighten the steel thingy a bit more.
The milky tft coupler bend and the filament wasn't able to pass trough.
Took it out, drilled it with a 2mm bit.
Printed 2-3 thinks ok. Fourth started to have big problems on retracts.
Took all out, the filament again wasn't able to pass trough. I suppose I could have drilled it again. But seems that there's a inner curvature.
So today installed a china ptfe coupler (the only spare left) and it's printing great.

So... Milky tft SUCKS BALLS.

It bends sooo fucking easily.

Oh on this second printer (the one that uses um2+ kit) the heater always goes +15 before finding the correct spot, but the 3dsolex same watts heater (on the other umo+) always lands perfectly (same pids). So um2 hotend it's nice but.

I bet 10 bucks than as soon people start to need yo replace their couplers, the forum are going to flooood with people complaining.

[Dim3nsioneer]

Did you get in contact with Carl? I use the TFT myself and sold quite a number of them so far and got no complaints... so maybe it's a single case...?

[Neotko]

Maybe I don't know. It was the first tft not full white coupler from him. I did sent him an email this morning with a full diagnosis. The thing it's that the speed it tookto deform was just sooo bloody fast. China coupler been printing nonstop since the morning. I'm on a non stop print week so this was really unexpected.

[Neotko]

hi

Do you know if by using the i2k the extruder needs more heat to work? I ask because...

Finally I got troubles again. This fking hotend pfff. Hate/love

So I took out all and the origin of the troubles seems that was the nozzle (e3d) internal had some weird stuff. And the i2k was very damaged from the 4-5 leaks it suffered.

S I installed a new i2k (0.5 mm) that carl sent me to test and used the old old 3dsolex coupler that I thought was dead (not sure yet anyway). And the first thing I noticed it's that I can extrude (suddenly) at 5-10C less. I measure this by the amount of filament it extrudes on the purge sequence. Pretty surprised....

Remember that I extrude this same amount everyday easily 15 times on 3 machines everyday since always, so I know how good/bad the temp it's by eye. It's the advantage of printing the same way always.

So my question it's. Does i2k affect the minimum temp to extrude? I never printed on um2 hotend without the i2k. And on all my test I need 10-15C more to print the same on um2 than on umo (reusing the same pt100from umo to um2 to confirm this).

So. Any i2k tests that proves that it doesn't affect the minimum temp to print? Or any test that confirms it?

So far this thinner i2k it's working just fantastic but since it's a long print I won't know until tomorrow...

Anyway thanks

[Dim3nsioneer]

It seems quite a number of users have this temperature shift after installing an I2K. Personally, I switched to I2K at the same time I installed the Olsson Block, and I could even take back temperature a bit. I once had a similar effect when the TF2K combination was not sitting well inside the hotend (I also got a leak then and a little bit of a mess). So in total I think it may be caused by a non-ideal assembling. But I have no hard facts for this. I started to turn the stainless steel coupler carefully by another maybe quarter turn after I think everything is mounted tight. This gives a bit more pressure onto the TFT.

[Neotko]

Sometimes I hate 3d printing. This time the print went everything ok, no underextrusion, except the areas with constant retractions (text areas). So I took out the extruder mk7 and after cleaning it the 'tooths' didn't even grip my finger nail, it just slips without really gripping hard. So, since this it's my oldest mk7 I can say that this stuff has a expiration date, something around 8 months constant printing and the tooths die.

I have inserted now a china um2 knurted bolt, hopefully it can give me a week or prints, or better put a slow print week until the replacements arrive in 5-7 days...

At least, it's printing nice and the atomic pulls shows no internal curve with the old coupler, no leaks...

More and more reasons to buy bondtech stuff and forget about the feeder for some time.

Edit. Indeed after 1h prints the filament it's flattening, grind. It can print but the width on some parts went higher than 2.00mm (because it flattened) so it's crap for 1.75. Time to take out one of the good ones and leave a printer to rest for a week (

[Neotko]

Holy mother F. I been fixing one of my um2 while also trying to keep making stuff.. HOLYF (sorry had to vent).

1. I took out my olsson china block
2. Installed a real no china block
3. Changed the i2k, coupler.
4. Heat still was crap on this one.
5. Debugged a problem on the heater.
6. Replaced.
7. Printed almost ok for a while
8. Drilled the inside ptfe/i2k to clean the hole
9. Printer almost ok for a while
10. Heavy retract prints started to look like crap.
11. Had to ramp temp to 238 to be able to print.
12. After each print, and some did fail, I had the filament showing very clear signs of excess of pressure from the extruder
13. Replaced the mk7 by other much older. This was 2 day process while installing different mk7s that I had as backup, testing a different IRobertI design, and loosing many meters of faberdashery.
14. In the end the new mk7 (old one that I don't like but can work seems) prints ok
15. Temperature still needed to stay on 237 (for 50-70mm/s 0.2 layers on 1.75 filament it's weeeird)
16. Did 15 atomics to test from where was the extra tension coming from and the point of friction it's the I2K
17. 3 hours ago removed the I2K
18. Printed something at 215C same files than before. PERFECT FREAKING PRINT And most important...

At 225C I was able to print with the I2K but (on this machine) I wasn't able to get the GLOSS effect on the toplayers. And trust me on this I print the same stuff over and over and over so I know how it should look at all times.

Now that the FREAKING I2K isn't on the machine I get a perfect GLOSS at 220C... That's 15C of big difference to me

But the most important think, took out the filament, the atomic doesn't show a mid point anymore (the i2k) of tension, and the filament doesn't show ANY sign of stress from the extruder...

So... I2K + PLA = 15-20C more to keep the same extrusion force and gloss finish.

It's been a freaking freaking nightmare to debug this machine

Ofc the MK7 that I bough from reprapworld are PURE CRAP. They loose the grap in 6-7months, and the 3 I bough 2 months ago just in case don't have enough grip to push an old lady with wheels down a cliff!

So... Now that my printer works I'll focus on getting a freaking bondtech. And after that, PIB tests!

F F F I2K and F F F reprapworld shitty mk7s

Oh also, lost a day because the heat in madrid was 40-41C and Colorfab was getting Flattened, increasing the Dia of the filament and ergo, increasing by a thousand the bowden pressure.