E3D v5 All Metal w/Direct Pinch skipping/clicking problem

I have a home built Taz with a direct pinch setup that had been working for about 6 months with a j-head MKV, recently that j-head clogged up with an actual blockage, so i decided to try this e3D all metal hot end while the j-head "soaks" in MEEK.



I followed all of the direction on the build except i choose to use a different thermistor (cant deal with those hair thin thermistor leads (#6 rather than #5)) and i change my marlin code to adapt to the #6. The final build if you ask me looks clean and is solid,. with absolutely no chance of shorting the thermistor (double insulated with PTFE tubbing). the plugs i use are the exact same plugs the ubis uses,. so they are well tested for use on a hot end, capable of the current, and the thermistor gets gold plated pins for minimal contact resistance,.



This is a direct pinch set up that i use on all of my printers without issue, (one with a ubis, one with another j-head, and another with a buda). this extruder has no room for the filament to bunch up, or jam in the feed path, and has only skipped beats in the past if i push the speed well past 100mm/s (i like quality prints so i tend to print in the 60-70 range anyway)



But with this hot end,. its a near constant fight to keep it from stalling the motor and skipping steps,. it will start ok, but then within the first few minuets it starts to skip, this of course starts to print voids,. and if enough voids happen it ruins the print,. I have tried every temperature possibly prior to burning the actual filament,. and i have found that if i start low, say 200c and then when the first skipping starts i bump it up to 205c, it will then print for a few more min until it starts skipping, then i bump it up to 210c,. few more min,. 220c,.. few more min,. by doing that i can get it to print for about 30min before it just totally locks up and then the print fails.

After the print fails, i cant even push the filament by hand anymore,. its more stuck than i ever have seen filament stuck before,. but if i pull it out,. cut it off, and push fresh in,. bam slides right through again, so no clog,. of course once i start a new print the time to lockup is 100% going to happen again,. somewhere between 20-30min of printing,..

I have the cooling shroud as low as it can go without going past the fins,. (started with it middle), in all situations the heatsink is only mildly warm to the touch i would almost say its cool to the touch, but not quite (can hold it indefinitely) it never really gets hot up there no matter where i put the fan really,.. I am using an ABS hotend plate to hold the top of it in place,. and that shows no softening or melt warping at all,.

I have slowed the printer down to 20-30mm/s,. still jams up every time,.

At this point iv wasted an entire week trying to get this thing to print,. i can tell that in that 20-30 min prior to jamming its printing exceptionally well,. so i really, really want to make this thing work,. but like others i am literately pulling my hair out on this one,.

So far i have only been able to print 3, 5mm step calibration prints (http://www.thingiverse.com/thing:24238) if i try to print anything larger,. it jams up before it finishes,. every time,. (the print in the picture was a small RAMPS fan bracket,. it just failed.)

I have serviced the 30mm fan (added super lube to the bearing shaft) to make sure its running at its best,. (adding the lube reduced the mAh draw by a fraction so it did help), and i have tried replacing the fan as well,. none of that helped,.

This printer is my PLA printer,. so i never push ABS or any other plastic through it,. i like to keep a hot end for every plastic so there is no mixing (makes cleaning nozzles allot easier),. so on this hot end i only have interest in tips towards making PLA go through it without jamming up.

Please don't make me switch back to that j-head,..
Any help would be appreciated,. Thank You,.

Alex

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

I'll play with adjusting the retract,. see where that gets me today.

Thanks, its been a lot of work. It started from the opensource Lulzbot taz v1 stl's and BOM, but i have heavily modified it, at this point every printed part (and many non printed) are non stock. https://www.lulzbot.com/

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

you know as i watch this 0 retract print test,. i was just thinking,. if the outside diameter of the thermal break (thermal pinch point, thermal bottleneck whatever you want to call it, the narrow bit between the heatsink and the heat block) is the same for a 1.75 and a 3mm version of the e3D shaft tube, then that's going to generate a vast difference in (and its clicking already that was fast) the heat transference since the thickness of metal at the pinch is nearly 2.5 fold for the 1.75mm version,. does anyone know if the outside diameter is different at the pinch for 1.75 vrs 3mm version?

yeah this print just stopped extruding with 0 retract (~8 min in) so that's not it,.

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

hmm,. n/m on that just took mine apart to look for problems,. the OD of the pinch on mine is 2.84mm so a 3mm version would obviously be larger,..

And looking at the filament i pulled out after this last jam, (i put the clean end in to check depth,. and its about 1.5mm deeper than i am holding it here) so its not really melting past the heat break,.. but it is melting inside the heat break,. though I am not sure if it should be melting in or before the heat break.

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

Thank you for responding and your determination to get this figured out =)

Yesterday I switched back to my j-head,. and I am up and running again,. i need to kick a few prints out today for a client,. but ill try "seasoning" the hot end tomorrow. Luckily my hotend holder is designed to hot swap =)

I also noticed that the thermistor I am using on the e3D is not as smooth (on the saw tooth) as the (also #6) that i have on the j-head,. so I am starting to wonder if I damaged mine with over heating when I soldered it (I use non leaded silver solder (high melt point) and I just read that thermistors can be easily damaged by high soldering temps,.. that i am certainly guilty of). SO, i'm going to wire up the stock thermistor that came with the e3D, with crimps, when I re try tomorrow. if that does nothing, then ill season,.

And ill get that modded fan duct printing on my ABS machine today.

More tomorrow I am sure.

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

Sorry had a hard time getting to this today,. but all of tomorrow i should be able to focus on it,.

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

I ran multiple tests with retract completely turned off,. got a bit of early drool for the effort, but no decrease in jamming/skipping at all.. i figure if it does it with it completely turned off no other setting with it turned on would help, aka while it may be a factor of the issue, its not the only one..

Going through the cleaning process right now, to do the "seasoning", as i imagine the oil has no chance to get to the metal if its coated with stuck on PLA,. this is bloody annoying,. more in an hour or three,.

Alex

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

ok,. i "think" i'v found the root cause of the problem,. correct me if i am wrong but pertaining to the inside barrel of the stainless steel heat break,. its absolutely imperative that that surface be relatively smooth,. some places even polish the inner barrel (i thought you guys did to but i guess I was wrong there.),. it took pulling out a digital microscope,. but i found multiple drill ridges inside my barrel,. MULTIPLE,. and at the worst one (a very hard edge) was where allot of burnt PLA was refusing to let go during the cleaning process, all of them where in the area of the heat break, a few before, a few after,. the worst one (where you can still see blackened PLA clinging) was right at the start of the heat break,...







(continued in next post due to 3 images per post limitations)

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble





The focus/depth of field on this is microscope are extremely narrow,. that's why the big chunks disappear in some images,. the ridges are at different depths, though they all seem to be near or around the heat break, but even a .5 mm focus shift can make things disappear into the blurr on this microscope..

I also shot a video that moves the focus along the inner shaft showing the multiple ridges, but i'm not a video guy and this file is 1.3gigs so i'm trying to figure out how to shrink it.

I will continue to try to clean this and season it,. but if this is as far "off" as i think it is in terms of "High quality surface finish" I would appreciate a 1.75mm heat break replacement sent ASAP.

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

Here we go this one shows the "worst" area the best,.the hard full circle ledge where a bunch of stuff is stuck,. and you can even just barely see the other ledges at the edge of the focus. this is right at the start of the heat break closest to the nozzle,.. nowhere even remotely close to smooth,.



I should also add that this barrel has only seen ~30-40, short, failed, test prints,. and only with clear/natural PLA, (what i always start new hotend calibrations with, the good stuff). so this stuck on black stuff, must be clear PLA thats so stuck its been baking there since the first few prints and has charred & hardened over just this short time.

I am hoping for a replacement at this point, but I am also suborn, and am curious if seasoning will actually resolve this bad of a inner barrel, so will continue to try to make this one work while i wait on the replacement.

I am going to leave this soaking in MEEK overnight to try to de-lodge the stuck on stuff, using a wood toothpick i tried to scrape it off but its not going anywhere without chemical assistance, and i don't want to scrape with anything harsher. tomorrow ill use natural cotton pipe cleaner soaked in more MEEK, with a little heat,.. to be continued,.

 

Re: E3D v5 All Metal w/Direct Pinch skipping/clicking proble

in the mean time, two thermistors ready to go,.



I didn't follow the directions,. again,. (sorry) i just dont like the idea of using kapton tape as an electrical insulator (more worried about the adhesive not being electricaly neutral, than the film itself), and right off the bat trying to use it was problematic. So i used two different sizes of PTFE tubing to make the super thin thermistor wires, double insulated, and a whole lot stronger. I decided to fold back about 5mm of the thermistor wire to help the crip hold the wire, and then used high temp adhesive heat shrink to insulate the crimps (hot air shrunk with thermistor kept cool wraped in a damp paper towel). I don't see how this could be problematic vrs the kapton instruction. (In my opinion its easier to assemble, and only added about 20 cents to the cost.) so the Semitec is ready for the taz once the barrel is cleaned and seasoned (or completely replaced), and then i also prepped a printrbot thermistor,. I figure if all else fails ill try this hotend on my ABS printer while waiting on the replacement heatbreak.