Canola Convert

[techstorage]

I'm perplexed why folks are having issues and turning to canola oil. What are you retract settings - length AND speed? My experience (and I've been on the soapbox about it for 2 years now) is that a fast retract (anything greater than say 25 mm/s with a 1/75mm filament) are BAD BAD BAD for PLA. I run at 20mm/s and 1.5mm retract and have printer 1000s and 1000s of hours and meters of PLA for almost a year no with NO plugging or issues. Perfect prints every time. If I change retract to 35mm/s I guarantee I'll have a problem.

Thanks for sharing your lessons learned by having a slow retracting time. One thing I notice in the few months that I have been at this, is not having the slicer config files consistent. I started with the download from the Seemecnc site but played around with the location of where to keep them to get them to work. Then after a RH software update they had to be reset and now the RH just stopped working. When I reset the config files the reverted back to a 5.4mm retraction at 100mm.

As far as this thread and the canola convert, I can see its merits for a faster retraction. The melted plastic is sticking to the hot end and when changing direction of the flow with the sticking properties of the plastic and hot end will cause the jam. Slowing things down has worked for you, but with some lubrication between the hot end sides and the plastic pool inside, faster retractions may be able to be achieved.

I am thinking of purchasing a spray can of Tungsten Disulfide Nano-Lubricant to put into a new end to see if this would be beneficial. For now I have slower settings and Canola.

[mhackney]

RamTechRob, I use KISSlicer but this stuff is pretty consistent with Slic3r
Here are my values for PLA but remember, I am running a Kraken hotend with nozzles that have a .75mm long bore (.4mm nozzle). These values are highly hotend / extruder dependent:

Length = 1.5mm for prime and suck, 2mm for wipe
Lift Z = 3mm (this is just how much the nozzle lifts when it needs to move from point A to point B or after a destroying
Speed = 20 mm/s
Extra length on restart = NONE
Minimum travel after retraction = 1.5mm

[mhackney]

techstorage, my issues with artificial lubrication are:

1) the lubricant can (and likely will) affect the bonding between extruded filaments
2) not all filaments are going to like having canola oil in the Bowden tube, extruder, hotend. Nylon for instance and probably ABS. If you only print PLA then not an issue (except for point A)
3) unnecessary complication, I prescribe to the KISS principle (no pun intended since I use the KISSlicer!)

But to each their own and if you have a system that works as reliably as mine and use Canola, Cheers!

[Tinyhead]

I believe it was bubbasnow quite some time ago that mentioned slowing down the retract speed and shortening the length. I tried both and like other people, I would get crazy stringing. I might as well have not had retract on at all. I would also lower the temperature down as far as I could take it before the extruder would start to skip. I don't know if most of the retract length was just being lost in the length of the bowden tube or what. I think the filament you use plays a pretty large roll in all this too. Different manufacturers will produce completely different results.

mhackney, do you happen to use a specific filament manufacturer to get those good results?

[mhackney]

I think the nozzle geometry has a LOT to do with it. I use filament from everyone - eBay vendors, ColorFABB, Ultimachine, etc. So far I have not met a filament I can't print. Sure, some are better than others but I have yet to find one that is horrible (except the "Pink ABS" that I thought was PLA fiasco from a year ago!).

All 8 printed parts on this reel were printed (in 2 different sources of PLA both from eBay) and NO cleanup was necessary before assembly. These are the as-printed parts.

[img]http://mhackney.zenfolio.com/img/s7/v16 ... 3866-5.jpg[/img]

[img]http://mhackney.zenfolio.com/img/s7/v15 ... 4227-4.jpg[/img]

You can see the vey high res version of this and a few other reels here: http://mhackney.zenfolio.com/p803008320" onclick="window.open(this.href);return false;
These were all printed in the last few weeks, no cleanup required, all rotating part tolerances are spot on.

[Tinyhead]

Those look amazing. Always been dazzled by the use of the infill pattern as part of the prints.

Those prints, to me, generally wouldn't cause much stringing as they're going to be printed horizontally. If I was printing something like a perforated vase, I would be spending as much time in clean up as it takes to print the job. Obviously some things are better than others, but when it comes to many many retracts, I simply cannot seem to find a sweet spot to eliminate the strings. I've seen videos of others' printers doing those jobs and not a single loose string. Makes me want to pull my hair out.

You can see on something like this where there are a lot of retracts at the bottom, I've got myself a good amount of cleaning. Obviously the shorter the distances the worse off. Any cooler and my extruder is skipping too. Maybe I should try making the spring tighter and see if it makes a difference.

[RAMTechRob]

mhackney, thanks, I will give it a try!!

[DavidF]

Mhackney, I got some filament from e bay that might give you some trouble. Its the only thing that I have ever had jam my e3dv6. I have named this very special filament "cat hair filament" The first 1/4 of the roll had little black hairs (maybe string) infused into the filament. Pretty interesting stuff...

Aside that, nothing I have thrown at this nozzle has ever had a problem. Ive run abs, pla, hips, nylon, ninja flex, from a bunch of different suppliers switching between them without a single problem (knock on wood) hope im not jinxing myself here. One thing I do when switching filaments (if the previous filament had a higher extrusion temp) is to heat the hot end up to the temp of what ever filament I was last printing with then hand feed some of the new filament thru and yank it back out with out the bowden tube disconnected to clear and clean the nozzle before printing. I do this several times with short lengths of filament maybe 6" or so and alternate the end so its all ways a fresh end entering the extruder. My retractions are set to 2mm and 30 mm/sec and my typical printing speeds are between 30 and 40 mm/sec. I love the V6 and have never had to diassemble it even with the "cat hair" filament issues.
I ordered some PVA filament today and hope to have it by the weekend. If it prints well I will be ordering another V6 so I can go dual extruders.

[DavidF]

Those look amazing. Always been dazzled by the use of the infill pattern as part of the prints.

Those prints, to me, generally wouldn't cause much stringing as they're going to be printed horizontally. If I was printing something like a perforated vase, I would be spending as much time in clean up as it takes to print the job. Obviously some things are better than others, but when it comes to many many retracts, I simply cannot seem to find a sweet spot to eliminate the strings. I've seen videos of others' printers doing those jobs and not a single loose string. Makes me want to pull my hair out.

20140621_094205.JPG

You can see on something like this where there are a lot of retracts at the bottom, I've got myself a good amount of cleaning. Obviously the shorter the distances the worse off. Any cooler and my extruder is skipping too. Maybe I should try making the spring tighter and see if it makes a difference.

Thats a damn nice print!! where is this model file? I want to print it!!

[McSlappy]

Tiny, that's an awesome model! Did you do that?

[mhackney]

Tinyhead, those photos may not show the "challenge" so consider this one:

[img]http://mhackney.zenfolio.com/img/s7/v16 ... 7151-4.jpg[/img]

Those pillars - 6 of them all together - are all printed without stringing. The nozzle is zooming from one to the next in an almost star like pattern. You will see no striking and no telltale of stringing. I assert this is a case that could others a lot of stringing problems.

[mhackney]

I like it "cat hair filament"! I haven't come across one of those... yet!

tinyhead, can you print the "Pyramid" without stringing? Take a look at my photo in the pyramid thread from last year. This is a great thing to use to fine tune and understand the characteristics of a filament. There are so many factors involved and you just have to take a methodical approach to understand their effects (and combinations of effects) and then use that to eliminate them. No doubt there will always be a certain filament, on a certain day, with a certain slice of a certain thing that will cause some problem. But you should be able to eliminate most major problems.

[mhackney]

Ok, here's some food for though. I did a test this morning to show you how sensitive things are to stringing as a function of the nozzle bore length. I printed 2 identical parts from the same gcode. This was my standard 20mm/s retract, .75mm retract length, 40mms print speed, 185°C hotend, 55°C heated bed. The ONLY difference is the part on the left has a nozzle with a .75mm long bore, the one on the right has a 1.6mm long (stock) bore. This translucent black PLA is one of the more difficult PLAs I've run into but even it was conquered!

Sorry for the not perfect photo quality but I think it gets the point across (click it for a higher res version). The part on the left has almost no stringing as you can see - this is an untouched part, I removed it from the bed and put it on my photo stand. The part on the right is a stringy mess. It even has little blobuels at the base of each string so even if you cut the strings off, there would be a little bum on the posts.

And, I have a part I'm printing now with the "good" .75mm short bore but I've raised the hotend temp to 200°C and the print speed to 60mm/s. It looks like a stringy mess already (even worse than the part on the right in the photo) and it's not even complete.

[precisionpete]

Can you please clarify your "good .75mm short bore? What hot end and is it modified or stock?

[mhackney]

Sorry precisionpete, I assumed that everyone here knows about all the posts I made on the subject!

Hotend: E3D Kraken (but the V4 and V5 are virtually identical and I've had no problems tuning them).

I discovered early last year that the nozzle bores are quite long and even variable length - 2mm typically for a .4mm nozzle. I reduced the length (search for my instructions, drawings, etc here) to .75mm (after trying .5mm and other lengths, I standardized on .75mm). The hot end itself is stock, the nozzle bore is shortened. E3D took my research and experiments into consideration when they released the V5 and V6 hotend nozzles.

The basic idea applies to any hot end.

[precisionpete]

Thanks that clarifies.
I agree with NOT using any oil and have been working on a few simple things since my E3D really jammed last time.

[techstorage]

The numbers work for you mhackney with a modified head so they are only a starting point for me and I should play with temp and retraction to get better pla prints. This will need to be done on a quick print. Maybe the hollow pyramid file. 1/2 hour print time.

[626Pilot]

Sorry precisionpete, I assumed that everyone here knows about all the posts I made on the subject!

Hotend: E3D Kraken (but the V4 and V5 are virtually identical and I've had no problems tuning them).

I discovered early last year that the nozzle bores are quite long and even variable length - 2mm typically for a .4mm nozzle. I reduced the length (search for my instructions, drawings, etc here) to .75mm (after trying .5mm and other lengths, I standardized on .75mm). The hot end itself is stock, the nozzle bore is shortened. E3D took my research and experiments into consideration when they released the V5 and V6 hotend nozzles.

Have you told E3D about this?

[mhackney]

Absolutely and they have taken the info to improve the v6 nozzle redesign.

[Tinyhead]

I rigged my v5 with v6 nozzle and heat break up again. Took the nozzle out and took a drill bit by hand to the inside. I ended up taking a bit too much, but I'm at .7mm bore length now. After heating up the hot end and doing the tightening as per the specs, I literally can't even get the printer from home position to the print bed before it's refusing to print. I can't seem to get ANYTHING to come out unless I pull the filament out, cut it clean, then feed it in and keep it pushing through. If I stop at all it jams. To me it seems like heat creep, but I don't know what I could be doing wrong. My temps don't seem to be off or anything. Good airflow and cool fins on the heat sink. I'm just at a loss.

mhackney, when you drilled out the nozzle to .75mm, did you happen to use a standard bit? Or did you have something specific to give a certain taper inside the bore?

[mhackney]

I used a standard bit. You have something else going on that you need to get sorted. Once you have the nozzle installed and hotend up to temperature, what happens when you manually push the filament form the extruder end (If you have an ezStruder, depress the red lever and push the filament). Can you extrude a bead without a heroic amount of pressure? Is the filament snagging on something like the PTC coupler or an edge inside the hotend (maybe because the Bowden tube isn't inserted in all the way)?

[DavidF]

I rigged my v5 with v6 nozzle and heat break up again. Took the nozzle out and took a drill bit by hand to the inside. I ended up taking a bit too much, but I'm at .7mm bore length now. After heating up the hot end and doing the tightening as per the specs, I literally can't even get the printer from home position to the print bed before it's refusing to print. I can't seem to get ANYTHING to come out unless I pull the filament out, cut it clean, then feed it in and keep it pushing through. If I stop at all it jams. To me it seems like heat creep, but I don't know what I could be doing wrong. My temps don't seem to be off or anything. Good airflow and cool fins on the heat sink. I'm just at a loss.

mhackney, when you drilled out the nozzle to .75mm, did you happen to use a standard bit? Or did you have something specific to give a certain taper inside the bore?

Take a good look at the ss heat break and make sure you didnt bend/twist it any. They are pretty fragile. Im guessing that is your problem...

[Tinyhead]

Thanks for the replies guys.

Once the nozzle is up to temp, I can manually feed filament through like a champ. Melts a nice consistent bead and I could just keep going. Stop feeding for a couple seconds (not pulling any back or anything like that to mimic a retract of any sort) and try again... plugged. I can easily remove the filament and there is the standard cylindrical plug on the end. Cut off the plug and re-feed with no problems and starts melting again.

I've got a high CFM 40mm fan I might try and design a mount for to use on the E3D. See if more cooling on the heat sink helps - unless you guys say otherwise. To me it just seems like my melting point is too high into the heat break.

And no, I have no damage to my heat break. Always been very careful with it.

[mhackney]

can you post a photo of the plug? It sounds like you have a gap from improper setup.

[Tinyhead]

can you post a photo of the plug? It sounds like you have a gap from improper setup.

That's what the plug typically looks like. I'm not sure what I could have done wrong from the proper setup. I've got the tiny gap between the shoulder of the nozzle and the heater block. Heated up to high temp and tightened. Did the slight tightening to snug up the heat break into the heat sink... not sure what else to do. Followed both written and video instructions I could find in case I was going something wrong.