Extruder Drive Cannot Push Filament Through Hot End

[hcpl 0]

Okay good and bad news. The good news is that there was indeed material on the PEEK again so I cleaned that off. Measured the parts and it should be possible for the 2 to meet. So I tightened the PEEK on the brass pipe and noticed the brass got passed the part where the PLA was before... only to realize I forgot the alu plate in between. Unscrewed and started remounting with everything in place. While mounting I started to heat up also anticipating perfect extrusion.

A little distraction from my kid asking about the wifi on her tablet. Went away a few minutes to check. Got back and started to finish tightening the PEEK on the brass, not realizing it was all heated up already and I was deforming the PEEK until the brass cracked!

I'm out for a few days until the replacement is received. The good thing is that I'll know what to check for when mounting.

[calinb 11]

Send me a PM immediately, hcpi. If you are in the U.S., I can drop my extra PEEK in a USPS priority box for cheap and get you up and running by Monday!

Or maybe you'd like a break from all this "Ultifun" for a while. I was an obsession for me for over a week. My wife says I look like hell! (Lack of sleep). I'm actually too old for all-nighters, I think.

[calinb 11]

Joergen's suspicions were correct, I believe. The root cause of my printer's inability to feed filament satisfactorily was due to a defective position of the Delrin rubbing block against the filament. After comparing mechanical drive dimensions between our machines, we found that Joergen's typical rubbing block operating position is about 0.5 mm less tight than my block was in its fully retracted position. Photos follow.

Zoom into this photo and inspect the diamonds on the right edge of the drive bolt image. Notice that only the top six diamonds are fully pointed, cut deeply, and "good." Widening the slot on my lathe enabled me to position only good knurling in the filament channel. This mod was motivated by Joergen's older drive bolt, which has much more aggressive knurling than these new drive bolts. I'm sure this mod is good for optimizing the drive capability of the new bolt, but it didn't solve my problem:

[calinb 11]

Done with the lathe now on to to mill! This slot provided the dimensional relief necessary to enable adjustment with the adjuster screw. It also keeps the filament centered! This was the key modification that made my printer function, I believe! And no, the adjuster wasn't previously binding between the two wooden plates. (I've always been aware of the reason behind the self-locking Nyloc-style nuts that were supplied in the kit.)

Finally, a useful Delrin rubbing block position! This is my new operating position.

And I can now fully latch the mechanism, exactly as it was designed to function!

I'm pleased that I optimized the drive bolt slot to position only the "best" knurling under my filament, because Joergen's back-revision drive bolt still has deeper and sharper knurling driving his filament, but I believe it was actually the additional relief in the Delrin rubbing block created with the ball end mill that fixed my Ultimaker. I feel the same about my V1/V2 hybrid hot end mod. It reduced the force needed to push filament though the hot extruder (maybe by 30% or, at most 50%), but the drive mechanism in its current configuration could have driven it! Still, either my careful assembly or the hot end or the additional pressure I provide between the Teflon and brass pipes (provided by milling 280 microns / 0.011" from the V1 nozzle) may have eliminated all internal leaks and a source of impediment to extrusion. I could have removed material from the end of the PEEK too, but brass mills very nicely and doesn't heat up and gum up. I've never attempted to mill PEEK insulating material. It would probably work just fine too, at lower feed and tools cutting speeds.

(end of dissertation)

[hcpl 0]

Calinb yours needed many modifications in order to work!

I checked all these details on my machine now and I have the same issue with the driving bolt. It needs to machined also in order to get the good part completely aligned in the driving slot of the extruder. Good to know. I'll keep that in mind if the new hot end is still not working.

The delrin part pushing the filament against the driving bolt is not an issue with mine (other than user error in the beginning) since I have the V2 version of that. You should really print that now you can. I have both and the difference is significant!

Nice color on yours! Happy printing.

edit: I just noticed another difference. You have a white clip in the grey part where the filament enters the bowden tube. Mine is the same grey color as the bigger part. It also has a rubber ringer underneath the clip. I think that is to protect the bowden tube when you let the filament enter by a driving extruder.

[calinb 11]

Yes--I will install the Bertho upgrade!

> edit: I just noticed another difference. You have a white clip in the grey part where the filament enters the bowden tube.

With the repeated tear-downs and reassembly necessary for debug, I broke my original gray clip. I used one of the extra white clips from the old hot end parts. It seems to work fine and I also printed the spacer to remove play from Thingiverse:

http://www.thingiverse.com/thing:22851

(I'm using both this spacer and the white clip.)

The Bowden tube seems to hold well and it does not move at all at either end with firm tugging and pushing.

[calinb 11]

Nice color on yours! Happy printing.

 

I forgot to mention that it's Speedball brand indigo blue ink. I used an airbrush to spray it thinned 1 part ink to 2 parts denatured alcohol (ethanol poisoned with methanol by the tax man here in the US, who would rather have blinded citizens than have them dodge the liquor taxes!) I selected ink instead of water base stain or paint because the more volatile ink carrier flashes off more quickly than water, and I figured it would be less likely to raise the wood grain or swell parts. Two 2 oz. bottles of Speedball ink could be carefully stretched to completely paint an Ultimaker but it would be tough to even add an Ulticontroller to the job. I used three bottles and have plenty of ink left-over for touch-ups. I was running out of my second bottle before I started to paint my Ulticontroller.

If I were to do it again, I'd lightly sand the faces of the plywood panels to remove any splinter fingers before painting.

[hcpl 0]

just reported some spam!

I didn't receive my new parts yet. I'll get back to this topic as soon as I have my new head so I can continue testing. Thanks for the color details calinb.