E3D V4 All metal hotend

[626Pilot]

When you assembled the head, did you put any PTFE tape around the threads? (Don't.) When you were done assembling the head and before it had ever run any filament, did you heat it up to 320C and tighten the nozzle further? If not, filament can creep into places.

[McSlappy]

Never used any thread tape.
I heated it to 290 as instructed by the e3d installation then did a final tighten. When I pulled it apart I didn't see any evidence of filament having been introduced between the heat-break and the nozzle threads, so I assume it was a decent seal.
I've done this every time I've reinstalled it.

[mhackney]

I am sure this is going to be one of those things that turns out to be simple when we look back.

Quick question, did you change your stepper motor current? I recall you were a little on the low side and a tweak up might be the bees knees! Try moving it up to 230. I run mine at 240 now with the fan installed. By the way, it is fine for steppers to run hot - 100-110°C in most cases. The steppers on my my big milling machine are monsters and you could cook an egg on them.

[McSlappy]

If we're talking about the 0-255 value on the stepper current, this line:

#define MOTOR_CURRENT {175,175,175,200,0}

I did bump it to 220, and ran it, but I didn't get a confirmation that this was indeed the value I should change, so I put it back to 200 as it is now.

[mhackney]

I would recommend leaving it at 220 to get a little more muscle out of the extruder driver.

[McSlappy]

Changing and printing now

[McSlappy]

I switched current to 220 and uploaded that... and did a couple of other things.

- Put an aluminium foil shield between the lower part of the fan and the heat block in case there was some air washing over the thermistor and giving me bad readings.
- Put slic3r back on it's default extrusion width settings (which I don't like)
- Switched the PLA to a brand new unopened pack.
- Set hot end temp to 200

I actually managed to finish the print! It was a little wobbly from heat (I think it's definitely too hot for this pla) but it actually finished! I was ready to say that my other PLA must have been to humid, but thought I should do another test first...
Exact same print, but back to my custom extrusion width settings and 190 degrees on the hot end... Couldn't even get it to extrude again... Ok back to 200, wait for the heat up... Nothing. No extrusion again.
Cried a little...

Manually reversed the filament and could feel that same rough resistance that I've felt before. Played with it a little, trying to figure out what it is that I'm feeling. Took the bowden tube from the hot end and manually moved the filament forward and backwards again (I've done this before of course, just doing it again for old times sake), and did feel a different, yet definite resistance. I wouldn't say that it's probably enough to stop an extruder, but it's something that shouldn't be there, and perhaps once added to the resistance of the hot-end it's compounded.

I think I've isolated it to the PTC connector on the extruder. It's a 3rd party one since the stock one blew out on a failed print a while back. Perhaps it's opening is smaller.
I have some more of the e3d PTC connectors, So I'm going to print an ABS version, tap and fit the e3d PTC to that and reinstall.

Isn't it wonderful to be able to print the parts we need?

I'll update later.

[McSlappy]

What's that part called which sits directly below the extruder which the PTC mounts to? That thick metal cylinder...

[Eaglezsoar]

What's that part called which sits directly below the extruder which the PTC mounts to? That thick metal cylinder...

It is called the heatsink.

[McSlappy]

The one on the cold end, not the hot end.

Well I'm not sure it matters anyway. I pulled the extruder mount apart to take measurements from it. I looked at the PTC connector, and it's not the constricting part of the unit anyway - the metal cylinder that I cannot name is more resistive than the PTC.

I fed a good length of filament through the PTC and that cylinder and it did have resistance when there were kinks, or stripped out sections, but nothing that would stop or slow an extruder.
I think I'm becoming frantic ha ha.

I'm putting it back together, and focus back on the hot-end where I think the problem lies.

[mhackney]

I don't know that it has a name, perhaps PTC coupler or PTC adapter.

One other thing to check, now that you've had filament getting chewed up, is to make sure the knurled driver and the path in the extruder are clean. The knurled driver can get loaded with plastic bits and becomes much less effective.

[626Pilot]

Sometimes I have to print PLA with my E3D at 225-235. Don't be afraid to play with higher temps. There are three different kinds of PLA, each with its own heat range, and they don't tell you which you're getting!

[Eaglezsoar]

I don't know that it has a name, perhaps PTC coupler or PTC adapter.

One other thing to check, now that you've had filament getting chewed up, is to make sure the knurled driver and the path in the extruder are clean. The knurled driver can get loaded with plastic bits and becomes much less effective.

The name on the SeeMeCNC site is Groove Mount to Bowden Adapter

IMG_1.jpg (18.73 KiB) Viewed 14654 times

[mhackney]

A name for everything!

[McSlappy]

Awesome, thanks for finding that out. I did try to find the .stl file for it, but I don't think the .stl's contain that one...

As I was putting it back together I fed filament through the parts before adding another, trying to isolate the resistance I was feeling.
Alone each part is smooth and has very little impeding filament.
Once I put the extruder together with the Groove Mount to Bowden Adapter I noticed that it was really hard to push the filament down into the bowden tube. I determined that the GMtBA was not perfectly aligned to the groove that fed the filament into it. For an unused piece of filament it wasn't too bad, but for one which had been deformed by the teeth it was tougher, and by filament that had been chewed by the teeth it was very difficult.
I took a countersink bit and increased the chamfer on the GMtBA, checked that filament fed through it nicely, then sent a print. I was all giggly and was typing here premature proclamation of a solution.... When it started stripping the filament again (not skipping).

Just now I pulled the PTC and bowden tube from the extruder side, allowing me to use my hands to push filament through the bowden tube into the heated hot end.
I find that I cannot get the filament to feed through, even though it had just been running for 30 minutes before.
I 'feel' a definite catching with enough definitely enough force to stop an extruder.
I was able to pull on the filament to free it, but it also required a significant amount of force, probably more than enough to stop an extruder also.
Once I pulled the filament out I was able to reinsert it with significant force to bypass whatever was catching on it.

There has to be some sort of something inside the e3d catching the filament, though I cannot fathom what it is since the insides look great. It's also so confusing since whatever catches doesn't always catch.

[SanjayM]

Hi all!

Long time since I checked in here, perhaps too long. Things have just been crazy at E3D and I don't have as much time as I'd like to peruse forums and the like. McSlappy kindly got in touch via the support system to let me know about this little saga.

The main culprit for jamming is usually heat - if you heatsink is warm or hot to the touch (even on that bottom fin closest to the heater block) then something is wrong. The included 30mm fan and duct should absolutely provide enough cooling. It looks like you've got cooling sorted

The next thing is to look for areas in your system where the filament isn't "guided" or properly constrained from side to side where it could be bending slightly and absorbing force from the extruder. You should make sure that your couplers have the tubing fully inserted into them and the tubing locked into place by pulling up on the collet while pushing the tubing into the coupler. If the collet isn't "locked" then the tubing can move with the filament during retraction and the like.

You might want to check your retraction settings, if you have excessively long retraction this can cause issues. What settings are you running?

You might also want to check your thermistor is configured correctly - we had some duff advice in our manual about which thermistor table to run. You should almost certainly be running table #5 for a semitec. Clarification here: http://e3d-online.com/index.php?route=e ... blog_id=19 having the wrong table will give you readings that are higher than actual, which would mean you are running at too low of a temperature.

Your methodology of checking the alignment with a backwards 2mm bit is spot on, and what we do here. It seems like all is well there.

Next thing is filament, some PLA types for whatever reason (usually cheap stuff) have something in them that makes them incredibly sticky and unprintable. It looks like you've tried a few different reels, but are they all from the same manufacturer? Have you tried different brands/sources?

Finally, if you want to eliminate the hotend from the equation I'm totally happy to swap it out for a brand new set of metal parts, just send it back to me, email me a tracking number and we'll get you a replacement sent as soon as we have the tracking number. It could well be some odd bit of witchcraft that is causing it not to print properly, I've 2 hotends (out of literally thousands) so far that have come back to me after much troubleshooting that look perfect, no misalignment, no bad surface finish, essentially appear perfect - but mysteriously just won't print.

You guys might also be interested to know that we've just opened a forum where people can get support and answers for general questions as well as swap designs for mounts etc. I saw that people were asking about having a sub-forum for discussing things, if you want I can create a sub-forum in our forums for you SeeMeCNC people to collaborate in. I monitor those forums very directly and you're likely to get a response same day there as opposed to same month here!

We're also running a competition to get useful content into the forums.
By way of some encouragement we are giving away some store credit for the best 10 posts made before Midnight (GMT) on the 31st March. The rewards for the best posts as follows:

Winner
£75 Store Credit

2nd Place
£50 Store Credit

3rd Place
£30 Store Credit

4th - 10th Place
£20 Store Credit

The posts can be on anything, however we are particularly looking for:
Assembly guides - printer specific or not
Reports of prints in interesting materials - very high temperatures?
Troubleshooting guides
Hacks & Mods
Printed Add-Ons - Carriages, mounts, ducts, etc..
Kraken-related experiences

Details here: http://forum.e3d-online.com/viewtopic.php?f=11&t=5

I'll make a note to check back here to see how you guys get on with the troubleshooting.
Cheers,
Sanjay

[McSlappy]

Thanks Sanjay, good to see you here again

I'll go through your list and give feedback on each step:

- Heatsink. I check periodically, but even the lowest fin is probably not above body temperature. I have to say that heat seems to be the most likely culprit in this, since most prints will run for 20 - 30 minutes (if they actually start) and then fail. I just can't figure out where. I've cooled the board, cooled the extruder, checked the hot-end cooling (which is working very well)
- Guiding. I did think I'd figured it out at the extuder end, but after chasing that one up, it didn't seem to be the problem. I fully insert the tubes into the PTC, until the tube bottoms out. Just for kicks I tried backing them off too, but that didn't help.
- Retraction settings. I've run them from 0 to 4mm, which is what I'm set at currently.
- Thermistor table. I'm not sure about this one since our firmware is not laid out with temp_sensor as a variable.
- Filament. Yes I have 2 rolls of identical PLA, though I do have another brand coming soon so I'll test that.
- Replacement. I don't think I'm ready for that yet, especially since I cannot see anything wrong with the head. I fully expect to slap my forehead when I discover whatever the cause of this is. Perhaps I have one of the rare versions with a ghost in the machine. We can cross that bridge later if need be.

Thanks for jumping on here and saying hi, I did have a little dig about your new forum and yes I might just go over and say hi

[626Pilot]

If you want some reliable PLA, try this: http://www.amazon.com/SainSmart-PLA-151 ... rt+red+pla

Out of all the PLAs I've printed with, this is the stuff that's been most likely to "Just Work." I've never had to put it in a dry box and it's so rare that it jams that I'm genuinely surprised when it does.

Don't be afraid to play with weird, ABS-like temperatures. Try temps from 170-250. You might find that whatever filament you have is "weird" and will only flow reliably at what seems like impossibly high temperatures. I've had two E3Ds and they both printed best at temps 10-20C (if not more) above what my Budaschnozzle liked.

[McSlappy]

I'm hoping the PLA I get will be a good reliable one since it's locally made. I've heard good things about the sainsmart stuff and if this new PLA isn't good I'll definitely just go for that.

Do you find the PLA very stringy at those temps? Printing the PLA at 210 was enough to make my prints very stringy.

[626Pilot]

Each PLA is different. The temperature one flows great at, won't work at all for another. I find most PLA filaments won't go through my E3D at all at 210 because it's too cold.

[McSlappy]

Just ran it at 220, which was very stringy and popping. It ended up stripping the filament out again.
I know that when this filament isn't jamming, it's low end is about 165, but has decent flow at 175, I usually run it at 180. Even at 200, as long as it's not jammed, it will just drip from the nozzle like honey.

I may just wait until my new filament gets here, at least I'll have a comparison, and rule out PLA. I'm running out of ideas.

[mhackney]

Gentle reader, after printing literally 100s of parts in many (>15) different PLAs for the past few weeks I ran into an abnormality in the 3D printing universe yesterday. Let me explain...

I acquired this very pretty transparent yellow PLA that looks like lemon drops - I have not used it yet. I measured its diameter at 1.71mm - on the high side for most PLAs I have (they are typically 1.66-1.69mm). I loaded it up, did the "find a good extrusion temperature" test and 190°C looked good. I then loaded my gcode (that tenkara line holder) and gave it a whirl expecting to see a nice set of parts come out of it. WRONG! During the first layer - and ONLY on the snowflake shaped part which prints second - I experienced filament starving on the infill (but not the perimeters). I let it run a bit to see if I could learn something. It was a fail, the next layers got progressively worse. Finally at layer 4 I had to abort, not bearing to see imperfection on my print platter™!

So the troubleshooting began. First I checked the filament path and it did seem a little "snargly". One thing I do I may not have mentioned is simulate rapid retracts by pushing-pulling the filament 10-20mm rapidly a few times. When I did that, I noticed a very obvious snag on the push. Further debugging pointed at BOTH the extruder and "somewhere in the hot end path". I started taking the Bowden fittings off and that's when I noticed that the PLA had a VERY pronounced pattern of ridges embedded in its surface along one side. "Logical", I thought, the hobbed gear has teeth to grip the filament. What was different about this was the color of this material made it very easy to see the tooth marks and through to the other side of the PLA. On the opposite side of the tooth marks was a subtle but matching pattern of "micro lumps" (for lack of a better term).

The tooth marks are very "catchy" and will snag on anything. I think this material may be a little softer than some of my others so the teeth marks are deeper and are parroted on the other side of the filament. The raised tooth marks and lumps combine to make the filament significantly larger in diameter than the source filament - which was already on the large side. Combined with the roughness of the teeth marks, anything in its path that it can snag on is a problem. During normal printing this may not be an issue since, like the hairs on a dog, the tooth pattern lays back in one direction. But throw some retracts into the mix and things change quickly! Now those laid back marks are like file teeth looking for something to grab. And grab the do. That's why the fill of the snowflake showed the problem immediately. There must be 20+ retracts filling those odd shapes whereas on the round part there are 2. And many of those 20 are in very rapid succession to fill tight corners.

To validate my theory, I switched to my known "good" licorice colored PLA and printed flawlessly, switched to lemon drop PLA and again, and experienced filament starving on the snowflake first layer (and I swapped the print order so the snowflake would print first).

"Ok" I thought (I never talk out loud when I'm doing this stuff, my family already thinks I'm one matchstick from snapping), I think the raised tooth pattern is causing problems. "So what to do about it?" At precisely that moment I looked at the box on my desk overflowing with extruders, hot ends and electronic components and caught glimpse of a hobbed gear on a direct drive extruder that I experimented with last year. It was magnificent, the teeth were at least twice as fine as the stock EZStruder teeth and not nearly as deep or sharp. "Hmm, can I substitute it for a quick experiment?" I thought. Turns out it is a direct replacement for the stock! I installed and aligned it, pulled the gnarled up filament from my Bowden. Paid homage to the 3D printer deities and pushed "Run".

I watched the filament coming up the Bowden, it had a nice, unmarred, surface. I watched the first layer of the snowflake part go down smoothly and with the precision and perfection I've grown to expect from my Rostock. Layer upon layer went down flawlessly. No filament starving, no skipped steps. Here is a photo to show the results - bad, bad aborted first 4 layers on the left and completed, flawless, lemon drop part on the right.

[img]http://mhackney.zenfolio.com/img/s8/v83 ... 2201-4.jpg[/img]

I have now printed 4 of these with no problems. The filament coming out of the extruder is nice and smooth with an ever-so-slight tooth pattern from the hobbed gear gripping it.

So, I think the aggressive teeth on the stock drive gear can cause problems with certain materials. Perhaps there is a way to smooth the path throughout the system so the raised "teeth" on the filament are not problematic or perhaps there is a way to "detune" the stock hobbed gear so it is not as aggressive.

Of course, this is still a very limited test and on PLA only. I anticipate this finer tooth hobbed gear will be fine on ABS< Nylon and other materials but needs to be tested. But I did want to get this "out there" for consideration in case it may help.

[Eaglezsoar]

A very good writeup. The one you used to replace the stock seemecnc one sounds like a MK7 in case someone is looking for one.
If I have the same problem the MK7 sounds like what I would use to replace the stock hobbed gear. I see no reason why you can't
use the MK7 permanently except for you because you are always experimenting with the exotic filaments.

[mhackney]

Good call Eagle, it is a MK7 drive gear!

I don't know this company but the price is reasonable and as you can see a much finer tooth than our stock gear.

cheers,
Michael

[Cleveralias]

Thanks Sanjay, good to see you here again

I'll go through your list and give feedback on each step:

- Heatsink. I check periodically, but even the lowest fin is probably not above body temperature. I have to say that heat seems to be the most likely culprit in this, since most prints will run for 20 - 30 minutes (if they actually start) and then fail. I just can't figure out where. I've cooled the board, cooled the extruder, checked the hot-end cooling (which is working very well)
- Guiding. I did think I'd figured it out at the extuder end, but after chasing that one up, it didn't seem to be the problem. I fully insert the tubes into the PTC, until the tube bottoms out. Just for kicks I tried backing them off too, but that didn't help.
- Retraction settings. I've run them from 0 to 4mm, which is what I'm set at currently.
- Thermistor table. I'm not sure about this one since our firmware is not laid out with temp_sensor as a variable.
- Filament. Yes I have 2 rolls of identical PLA, though I do have another brand coming soon so I'll test that.
- Replacement. I don't think I'm ready for that yet, especially since I cannot see anything wrong with the head. I fully expect to slap my forehead when I discover whatever the cause of this is. Perhaps I have one of the rare versions with a ghost in the machine. We can cross that bridge later if need be.

Thanks for jumping on here and saying hi, I did have a little dig about your new forum and yes I might just go over and say hi

My money is still on friction somewhere between the extruder and the hotend. Did you resolve that catching you felt where the bowden meets the heat sink? I also put a very slight bevel on the entrance like I believe you did. Do you feel a catch where the aluminum heat sink meets the stainless heat break? How about heat break to nozzle?

One more thing to consider if you haven't is your bowden tube itself; I have one that turned out to be just a tad narrow, and when a slightly larger or more eccentric filament would get deformed by the drive gear it resulted in enough friction getting the filament through the tube to cause problems.

Good luck!