E3D V4 All metal hotend

[mhackney]

Thanks for the length Polygonhell. I remember reading that page but forgot about it. Some good information. That's interesting about the J-Head reducing to .5mm. The method I'm using - if you can get the PLA plug out - not only allows accurate measuring of the orifice length but also shows the profile of the melt zone in the tip. I've been cleaning my garage and shop and moving piles of stuff from here to there and then moving smaller piles from there to here and, finally, moving these smaller piles into drawers. Thanks Carl! I'll start to make some plugs later tonight of my nozzle collection. I think this is an interesting line of exploration and the E3D tip certainly is at the long end of the scale.

Cheers,
Michael

[Eaglezsoar]

When one of you guys get a chance could you take a look at these prometheus drawings and give your opinion on how well these would work on PLA.
They show the bore length and other critical specs. https://www.flickr.com/photos/87676108@ ... 930743154/

[mhackney]

I'm no expert but I like the bore on this hot end. 60° cone leading up to a 1mm long nozzle bore. Don't know if 1mm is too long or not but it is in the ballpark of other hot ends. The E3D hot end has a very flat cone, it must be like hitting a brick wall when the melt comes down the hot end! Not sure how the cooling is going to work with SS up the entire bore of the aluminum heat exchanger.

[Eaglezsoar]

I'm no expert but I like the bore on this hot end. 60° cone leading up to a 1mm long nozzle bore. Don't know if 1mm is too long or not but it is in the ballpark of other hot ends. The E3D hot end has a very flat cone, it must be like hitting a brick wall when the melt comes down the hot end! Not sure how the cooling is going to work with SS up the entire bore of the aluminum heat exchanger.

Thanks for your opinion. It is becoming quite difficult to know which of the all metal hotends will reliably do PLA. You say you are not an expert but you are the closet thing to being one that we have on the forum. You and Polygonhell are experts on such matters as far as I can tell and still after all you have done the PLA printing problems rears it ugly head.

[mhackney]

Well, I could print PLA all year with the SeeMeCNC or J-head hot ends. They work fine. But the quality I was getting with the E3D and Kraken is noticeably better. The small melt zone and sharp transition to cold (especially on the Kraken) result in visibly better prints, less stringing, blobbing, etc. Everyone at the NYC show last week commented on the quality of finish on my gold PLA fly fishing reel. It really is nice. Now if I had a smoothieboard!

I think we are on to something with the long bore on the nozzle. It could explain a lot of the problems we are seeing. Today I cleaned and organized, tomorrow I'm going to drill an E3D nozzle to shorten the bore AND increase the cone angle to 60°.

[Broose]

A few thoughts...

mhackney- I like your idea of freezing the nozzle to remove the plug. Since the coefficient of thermal expansion of PLA is about 4 times greater than brass, when you lower the temp it should shrink more than the brass nozzle does.

I'm very curious to see if decreasing the nozzle hole length on the E3d will reduce your clogging with PLA. I suppose the tradeoff may be more oozing or retraction issues, which I've been very happy with on the E3d.

Too bad E3d doesn't show the internal dimensions of the nozzle in their drawing: http://files.e3d-online.com/Drawings/E3 ... Nozzle.png

I like the idea of a contiguous heatbreak/nozzle in the Prometheus to eliminate clogging, but I imagine stainless steel does not make the best material for the nozzle due to its low thermal conductivity. I wonder how it performs at higher print speeds

[mhackney]

Made some measurements of the bore length of some nozzles. First, here's the setup. I make sure the bore is clean then hold it in needle nose pliers. I have a 3" length of PLA at the ready. I then heat the nozzle with a little butane torch MILDLY. When the too is just hot enough to allow the PLA to flow (takes about 10 seconds or less) I push the PLA in until a little nipple comes out of the end like this:

Let this cool, do not touch the protruding nipple. When it is cool enough to touch, cut the protruding filament off with a single edge razor blade and place in the freezer for several hours. Put a pair of needle nose pliers in the freezer too. When ready, use the frozen pliers to pick up the nozzle - that way it does not warm up too fast. Grab the PLA and pull gently. Don't force it. It takes about 10-15 seconds for the brass to warm up from air temp and expand enough to let the PLA slide out. It will and will look like this:

As you can see, this J-Head is dead-nuts on at .5mm bore length. Interestingly, the cone is also very flat like the E3D.

I also measured three other nozzles and they were all within .5 to 1mm in length. Only the E3D has been anywhere close to 2mm.

Today I am going to chuck one of the E3D nozzles in my lathe and rebore the 2mm lead up to the nozzle bore. I'm shooting for .8mm. I don't have any data that substantiates this but I'm thinking a length to diameter ratio of 2 is a reasonable ballpark. I've googled to try to find any information and there is very little discussion about bore length in the RepRap world, everyone is focused on bore diameter. But, at these small diameters, there is a significant friction component and the longer the bore, the more friction. Stay tuned!

[mhackney]

Too early to claim victory, but...

First, I setup and printed a part that has been causing problems the last few days (a mini Kossel effector). I have been able to print it at 220°C but any lower and I get filament starving. One comment on this - I like the KISSlicer curved infill. It really puts the printer through its paces though and seems to exasperate this filament starving problem. Printed with straight infill, I can print this part at 205°C. I verified that the problem is occurring today. I then immediately took the nozzle off the machine and pulled the execs PLA out.

Down in my studio/shop/man cave I used a 2mm drill and twirled it between my fingers to remove any excess PLA - some did in fact come out. I then measured the length of the drill and then the length of the drill inserted into the nozzle. The difference, at least to a reasonable approximation, should be the length of the nozzle bore. I got 1.96mm (in reality, since the bit is pointed, it inserts a little into the bore of the nozzle so the measured length of the bore would be expected to be shorter than actual). I then chucked the drill in a pin vise (a handheld drill bit holder) and used it to gently lengthen the hole. I wanted to try this for several reasons - 1) it wouldn't require a lathe to fix the nozzle and 2) it gives very precise control. With just a gentle twirling of the pin vise between my fingers and a little pressure, the brass was easily bored. I frequently removed the bit, cleaned off the brass bits, and remeasured the bit and nozzle as above. I was taking about .1 to .2mm off at a time, so very precise control. At some point I decided to shoot for .5mm rather than the .8mm I mentioned in the last post. When I was close to the mark, I decreased pressure on the pin vise, twirled faster but for a shorter time. This was to take a fine cut and leave a better surface finish. I was able to get right at .5mm This entire process took a little less than 10 minutes and resulted in what I believe to be a reasonably accurate bore length.

Then, I did my frozen PLA test to capture a plug to see how long the bore actually is. I've gotten the technique down pretty well now so with a minimum of heat to melt the PLA and then dropping in a glass of ice water I can almost immediately remove the plug without freezing for 2 hours. Success, the nipple measured as close to .5mm as I could measure. At least it was significantly less than the 2mm stock bore!

Now, armed with a modified nozzle, I cleaned out the inside with a stream of isopropyl alcohol from a syringe with a 26 gauge needle to clean it out. Very little material washed out. I then mounted in my Kraken, rezeroed my Z axis, loaded my gcode, lowered the print temp to 185° where I used to print this particular PLA with a J-Head or the SeeMeCNC hot end (by editing the gcode, thus ensuring that everything else was identical to earlier prints), said a Hail Mary and pressed Print. Actually, before I did that I did extrude about 100mm of filament into the air to prime the nozzle and see how it would behave at 185°C. It seemed to flow fine and in fact, almost seemed to start faster when I hit the extrude button.

As I've been writing this (20 minutes or so) the part has been printing. Here are my observations:

• I'm successfully printing at 185°C (so far).
• The first layer went down incredibly smooth. One of the nicest first layers I've seen in a long while.
• I'm about 1/2 way done with the part. Earlier, I would get to about the 4th layer and have filament freeze issues. I'm at layer 22 of 41 and the part looks very nice. Very smooth layers, no indication of starving, no stringing, Absolutely no evidence of filament starving.

It is way too early to claim victory but I am very optimistic about this. It makes sense in retrospect and it is an area most of us completely overlook - the bore length. This is not to say that improvements like polishing the heat break bore, etc are not also contributors to filament freezing but I've systematically eliminated all of those to get to this point (no pun intended).

[Polygonhell]

Very interesting.

I think the real litmus test would be to establish that there is some significant variation in the E3d nozzles, it would give us a reason why some of them are very much worse than others.
But in retrospect a particularly high extrusion pressure would account for what I observe, KissSlicer tool paths are particularly bad.

[Eaglezsoar]

I am interested in the long term results of your experiment. Will it fix the PLA problems permanently, only time will tell.
It is fascinating as we wait in anticipation of your experiment, it feels like we are part of an audience watching Thomas Edison invent the light bulb.
Your experiment is especially fascinating because it has ramifications for all that are using the E3D.

[mhackney]

3 parts down - all perfect, no starvation all at 185°C.

Polygonhell, not sure what you mean by KISS having particularly bad tool paths? I've been very happy with KISS' tool paths compared to other slicers. However, that round infill is a stressed.

I suspect that the nozzle bore length might work for many users - raise the temp a bit, no "wild" infills, reasonable print speeds, sporadic printing, etc. But I print a lot (production parts) and am very demanding on quality and speed. I've emailed Josh and Sanjay and explained my findings and sent some photos, etc. Pointed them here too. I also asked if they have measured this bore length and if they think there might be variability. I got my E3D months ago and it was right at 2mm as were the 4 with Kraken.

[Polygonhell]

My comment about KissSlicer was more it seems to occasionally generate tool paths with seemingly maniacal retractions, usually when it's doing the fill the unspdersized gaps thing, or filling out the perimeters to the specified thickness.
In general I think it's still the best of the slicers with some caveats, Cura is very good right now, generates less crossing of edges and less retracts in general, and it actually bridges. I've been using that for my mechanical parts for the last couple of weeks.

I would be surprised if there were significant disparity in the nozzle lengths, these things have to be CNC machined in a jig, wondering if we can find the difference between the working nozzles and those that do not. I guess the higher extrusion pressure coupled with other factors like the overall finish of the stainless piece could be the answer.

[Nylocke]

Speaking of Cura, what are you doing for bridging Poly? for some reason Cura has been trying to bridge diagonally it seems, instead of crossing straight across from one side to the other, it prints like there isn't an overhang. Don't quite know how to explain it, but its been acting kinda weird for me. Also I've been having troubles with retracts and ABS, though that may be because my extruder split almost in half :/ (also might be due to El cheap sainsmart ABS, I haven't printed with my IC3D stuff for a while...)

[Tinyhead]

I tried the speed/temperature method on a print last night. In Cura, it was set for 30mm/s speed, 60% infill, 0.1 layer height with supports and would take 24hours. Once it got the bottom layer (20mm/s) down, I ramped up the speed using the LCD to 185% (55.5mm/s), and adjusted the temp to 230C and was using black PLA. With the stock hot end, I can run this black at about 190-195C, so 230C was putting it up there. The print ended up taking about 13hrs.

This ended up not only working for the entire duration of the print with no starving of filament observed anywhere, but it also never plugged due to retracts (another problem I've had), and it produced some of the smoothest walls I have seen on my prints to date.

3/4 done.

Complete.

I think the temperature could have come down as there was some decent blobbing on a portion of the backside of the supports, but it was just on the supports, so who cares. I thought the supports were going to be murder to remove due to the high temp of the PLA, but it snapped off nice and easy. Very surprised.

I'm very much liking the news regarding the drilling of the nozzle by mhackney. It would be nice to hear that it might allow printing at regular settings. While printing this time at high speeds was awesome and may work great on prints with a large layer surface area, small prints would stay too hot and sag without some serious cooling.

[mhackney]

Well so far so good today. As I ramped the speed up to >50 mm/s I did have to bump the temp up to 190°C but that is typical with other hot ends. I am still guardedly optimistic about this insight. I'm looking forward to hearing from E3D-systems and printing many, many more parts successfully.

That is a great looking and large party Tinyhead. It is good feedback to see that ramping the temp up to an extreme setting also worked for you too. I do still think that the nozzle might not have as good heat transfer as other hot ends since 1) the tip is not tightened against the heater block, a gap is prescribed to allow tightening the nozzle to the heat break, 2) the back end of the nozzle is tightened against less thermally conducting SS heat break and 3) the primary heat transfer path is through the threaded section and there is not that much surface area/threads to conduct the heat. I think this combined with the long bore result in two parameters that play against each other.

[Generic Default]

When you say Bore Length are you talking about the length of the tiny orifice drilled hole? I started a thread in the louge a few days ago about nozzle design, and this E3D thread just happened to turn into a conversation about nozzles. Maybe take pictures/draw sketches of your modifications and put them on this thread or the nozzle design thread?

[mhackney]

Yes, I am talking about the .40mm bore's length. There are photos I posted this weekend showing that the E3D bore is 2mm long - much longer than other nozzles. I simply drilled the 2mm hole that leads up to the .40mm bore a bit deeper with pin vise and 2mm drill bit. I'll try to draw something tomorrow.

[McSlappy]

I haven't commented much on this lately, just waiting for my new head (which arrived, but I've been now too busy to install >_< ).

I've watched this thread lately with great interest and I'm pleased that someone else was able to replicate and delve into the issues with PLA that I had. I'm curious now to see what depth my nozzles have. Even without knowing much about nozzle geometry I would have thought that 2mm was waaay to deep for a nozzle opening.

Michael keep us posted on the progress (as if you wouldn't) I appreciate your methodical problem solving

I'm also very interested in trying out a Prometheus and see whether the single nozzle/heatbreak combo will do wonders.

[JohnStack]

Yep, this thread is so long that it should have been broken into it's own sub-forum.

On my end, after reliable multiple shipments from Filastruder, I can't seem to get a real tight assembly without bending the heat break shaft at it's weakest point.

In the photo below, the two shafts on the left are bent and they caused (I think) two more hot end blowouts. On the right is another shaft - which is straight - but needs cleaning out as the result of a blown thermistor a while back.

All in all, I'm frustrated with these - the performance is great - as long as you don't have any mechanical or electrical screw ups. I've had and done both.

Here's why I'm frustrated:

1. Polygonhell's PLA problems.
2. You need to build a separate fixture to heat the assembly in order to avoid burning yourself in the process.
3. If you're doing this without, you're risking a bend to the weakest part of the heat break shaft.

These are all known problems - I guess I've reached my proverbial limit with hot ends. Surface adhesion and hot ends! Damn. Going back to SeeMeCNC's 99% solution - their hot end.

[Broose]

I am wondering if, as Poly said, there may be some manufacturing variation in the nozzle bore length. I'd love to know what the bore length specification is. I have unused .4mm and a .6mm nozzles and the bore length I measured was just about 1mm for each. I measured a 2mm drill bit bottomed out in the nozzle then subtracted the length of the 2mm bit to get the length of the hole. The difference was about 1mm in both cases.

[Polygonhell]

Using the same measure the drill concept yesterday, I measured the orifice on the first one I had at over 3mm, but that's the older nozzle design, the newer one I checked was closer to 2mm, but it's hard to get an accurate reading without knowing the angle of the original drill, since there is no way to know if the drill is seating at the bottom on the hot end. Although it gives you a maximum. I drilled one of mine out to a 0.4mm orifice, though I'm not printing PLA right now.

MHackney's measurement solution seems like it ought to be accurate, and that seems supported by the fact that he measures the JHead at 0.5mm. If your seeing a worst case of 1mm and he's seeing 2mm's then it would seem there is variation, I'm at a loss as to how this happens. I would assume that the nozzles are made from hexagonal stock on a CNC lathe, everything would be relative to the facing operation, and unless the actual code is changing between runs or the drill's offset is not correctly set, they should be identical to within 1/10ths of a mm.

[joecnc2006]

where do you get the tiny bits?

[mhackney]

The "frozen plug" method is the most reliable measurement since it captures the actual bore length, cone leading up to it and hot zone. It's easy to do. I measured the J-Head with the frozen plug technique.

[mhackney]

MSC, McMaster Carr and even Amazon carry the tiny metric bits.

[ceramichammer]

Well so far so good today. As I ramped the speed up to >50 mm/s I did have to bump the temp up to 190°C but that is typical with other hot ends. I am still guardedly optimistic about this insight. I'm looking forward to hearing from E3D-systems and printing many, many more parts successfully.

That is a great looking and large party Tinyhead. It is good feedback to see that ramping the temp up to an extreme setting also worked for you too. I do still think that the nozzle might not have as good heat transfer as other hot ends since 1) the tip is not tightened against the heater block, a gap is prescribed to allow tightening the nozzle to the heat break, 2) the back end of the nozzle is tightened against less thermally conducting SS heat break and 3) the primary heat transfer path is through the threaded section and there is not that much surface area/threads to conduct the heat. I think this combined with the long bore result in two parameters that play against each other.

Mhackeny,
I was out of the country all weekend but whenever I found wifi, I compulsively checked this thread. I'd never heard of freezing the filament out and some of those results are fascinating. That ~2mm bore length looks way too long. It may also explain why I had good luck with the 0.6mm nozzle. Even if it still had a 2mm bore length, there would be much less resistance and possible plugging and jamming. I have also been skeptical of the thermal stability and heat transfer to the nozzle itself. I installed a much larger heater block in hopes of making the temperature more stable. Even if the heater block temp is stable, the nozzle itself may be fluctuating wildly or even at steady state but at a much lower temperature. These "dinky" nozzles have next to no thermal mass and very poor conductive heat path because they aren't seated flush to the bottom of the heater block. Compare the thermal mass of a stock Ultimaker nozzle vs an E3D hotend.

[img]http://i.imgur.com/SDSpqvUl.jpg[/img]